diff --git a/packages/kbn-test/src/functional_test_runner/lib/config/read_config_file.ts b/packages/kbn-test/src/functional_test_runner/lib/config/read_config_file.ts
index 72926cae7dbc4..96fd525efa3ec 100644
--- a/packages/kbn-test/src/functional_test_runner/lib/config/read_config_file.ts
+++ b/packages/kbn-test/src/functional_test_runner/lib/config/read_config_file.ts
@@ -56,7 +56,7 @@ async function getSettingsFromFile(log: ToolingLog, path: string, settingOverrid
   return transformDeprecations(settingsWithDefaults, logDeprecation);
 }
 
-export async function readConfigFile(log: ToolingLog, path: string, settingOverrides: any) {
+export async function readConfigFile(log: ToolingLog, path: string, settingOverrides: any = {}) {
   return new Config({
     settings: await getSettingsFromFile(log, path, settingOverrides),
     primary: true,
diff --git a/src/es_archiver/actions/edit.js b/src/es_archiver/actions/edit.ts
similarity index 91%
rename from src/es_archiver/actions/edit.js
rename to src/es_archiver/actions/edit.ts
index 5e3a3490133c7..de63081a1ea1b 100644
--- a/src/es_archiver/actions/edit.js
+++ b/src/es_archiver/actions/edit.ts
@@ -22,12 +22,23 @@ import Fs from 'fs';
 import { createGunzip, createGzip, Z_BEST_COMPRESSION } from 'zlib';
 import { promisify } from 'util';
 import globby from 'globby';
+import { ToolingLog } from '@kbn/dev-utils';
 
 import { createPromiseFromStreams } from '../../legacy/utils';
 
 const unlinkAsync = promisify(Fs.unlink);
 
-export async function editAction({ prefix, dataDir, log, handler }) {
+export async function editAction({
+  prefix,
+  dataDir,
+  log,
+  handler,
+}: {
+  prefix: string;
+  dataDir: string;
+  log: ToolingLog;
+  handler: () => Promise<any>;
+}) {
   const archives = (
     await globby('**/*.gz', {
       cwd: prefix ? resolve(dataDir, prefix) : dataDir,
diff --git a/src/es_archiver/actions/empty_kibana_index.js b/src/es_archiver/actions/empty_kibana_index.ts
similarity index 73%
rename from src/es_archiver/actions/empty_kibana_index.js
rename to src/es_archiver/actions/empty_kibana_index.ts
index 386863ec18a43..5f96fbc5f996c 100644
--- a/src/es_archiver/actions/empty_kibana_index.js
+++ b/src/es_archiver/actions/empty_kibana_index.ts
@@ -16,13 +16,25 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
+import { Client } from 'elasticsearch';
+import { ToolingLog, KbnClient } from '@kbn/dev-utils';
+
 import { migrateKibanaIndex, deleteKibanaIndices, createStats } from '../lib';
 
-export async function emptyKibanaIndexAction({ client, log, kbnClient }) {
+export async function emptyKibanaIndexAction({
+  client,
+  log,
+  kbnClient,
+}: {
+  client: Client;
+  log: ToolingLog;
+  kbnClient: KbnClient;
+}) {
   const stats = createStats('emptyKibanaIndex', log);
   const kibanaPluginIds = await kbnClient.plugins.getEnabledIds();
 
-  await deleteKibanaIndices({ client, stats });
-  await migrateKibanaIndex({ client, log, stats, kibanaPluginIds });
+  await deleteKibanaIndices({ client, stats, log });
+  await migrateKibanaIndex({ client, log, kibanaPluginIds });
   return stats;
 }
diff --git a/src/es_archiver/actions/index.js b/src/es_archiver/actions/index.ts
similarity index 100%
rename from src/es_archiver/actions/index.js
rename to src/es_archiver/actions/index.ts
diff --git a/src/es_archiver/actions/load.js b/src/es_archiver/actions/load.ts
similarity index 84%
rename from src/es_archiver/actions/load.js
rename to src/es_archiver/actions/load.ts
index ea02ce9dd3ad3..404fd0daea91d 100644
--- a/src/es_archiver/actions/load.js
+++ b/src/es_archiver/actions/load.ts
@@ -19,6 +19,9 @@
 
 import { resolve } from 'path';
 import { createReadStream } from 'fs';
+import { Readable } from 'stream';
+import { ToolingLog, KbnClient } from '@kbn/dev-utils';
+import { Client } from 'elasticsearch';
 
 import { createPromiseFromStreams, concatStreamProviders } from '../../legacy/utils';
 
@@ -38,12 +41,26 @@ import {
 // pipe a series of streams into each other so that data and errors
 // flow from the first stream to the last. Errors from the last stream
 // are not listened for
-const pipeline = (...streams) =>
+const pipeline = (...streams: Readable[]) =>
   streams.reduce((source, dest) =>
-    source.once('error', error => dest.emit('error', error)).pipe(dest)
+    source.once('error', error => dest.emit('error', error)).pipe(dest as any)
   );
 
-export async function loadAction({ name, skipExisting, client, dataDir, log, kbnClient }) {
+export async function loadAction({
+  name,
+  skipExisting,
+  client,
+  dataDir,
+  log,
+  kbnClient,
+}: {
+  name: string;
+  skipExisting: boolean;
+  client: Client;
+  dataDir: string;
+  log: ToolingLog;
+  kbnClient: KbnClient;
+}) {
   const inputDir = resolve(dataDir, name);
   const stats = createStats(name, log);
   const files = prioritizeMappings(await readDirectory(inputDir));
@@ -64,12 +81,12 @@ export async function loadAction({ name, skipExisting, client, dataDir, log, kbn
     { objectMode: true }
   );
 
-  const progress = new Progress('load progress');
+  const progress = new Progress();
   progress.activate(log);
 
   await createPromiseFromStreams([
     recordStream,
-    createCreateIndexStream({ client, stats, skipExisting, log, kibanaPluginIds }),
+    createCreateIndexStream({ client, stats, skipExisting, log }),
     createIndexDocRecordsStream(client, stats, progress),
   ]);
 
@@ -77,7 +94,7 @@ export async function loadAction({ name, skipExisting, client, dataDir, log, kbn
   const result = stats.toJSON();
 
   for (const [index, { docs }] of Object.entries(result)) {
-    if (!docs && docs.indexed > 0) {
+    if (docs && docs.indexed > 0) {
       log.info('[%s] Indexed %d docs into %j', name, docs.indexed, index);
     }
   }
diff --git a/src/es_archiver/actions/rebuild_all.js b/src/es_archiver/actions/rebuild_all.ts
similarity index 84%
rename from src/es_archiver/actions/rebuild_all.js
rename to src/es_archiver/actions/rebuild_all.ts
index 9379a29c38130..1467a1d0430b7 100644
--- a/src/es_archiver/actions/rebuild_all.js
+++ b/src/es_archiver/actions/rebuild_all.ts
@@ -18,13 +18,12 @@
  */
 
 import { resolve, dirname, relative } from 'path';
-
 import { stat, rename, createReadStream, createWriteStream } from 'fs';
-
+import { Readable, Writable } from 'stream';
 import { fromNode } from 'bluebird';
+import { ToolingLog } from '@kbn/dev-utils';
 
 import { createPromiseFromStreams } from '../../legacy/utils';
-
 import {
   prioritizeMappings,
   readDirectory,
@@ -33,12 +32,20 @@ import {
   createFormatArchiveStreams,
 } from '../lib';
 
-async function isDirectory(path) {
+async function isDirectory(path: string): Promise<boolean> {
   const stats = await fromNode(cb => stat(path, cb));
   return stats.isDirectory();
 }
 
-export async function rebuildAllAction({ dataDir, log, rootDir = dataDir }) {
+export async function rebuildAllAction({
+  dataDir,
+  log,
+  rootDir = dataDir,
+}: {
+  dataDir: string;
+  log: ToolingLog;
+  rootDir?: string;
+}) {
   const childNames = prioritizeMappings(await readDirectory(dataDir));
   for (const childName of childNames) {
     const childPath = resolve(dataDir, childName);
@@ -58,11 +65,11 @@ export async function rebuildAllAction({ dataDir, log, rootDir = dataDir }) {
     const tempFile = childPath + (gzip ? '.rebuilding.gz' : '.rebuilding');
 
     await createPromiseFromStreams([
-      createReadStream(childPath),
+      createReadStream(childPath) as Readable,
       ...createParseArchiveStreams({ gzip }),
       ...createFormatArchiveStreams({ gzip }),
       createWriteStream(tempFile),
-    ]);
+    ] as [Readable, ...Writable[]]);
 
     await fromNode(cb => rename(tempFile, childPath, cb));
     log.info(`${archiveName} Rebuilt ${childName}`);
diff --git a/src/es_archiver/actions/save.js b/src/es_archiver/actions/save.ts
similarity index 83%
rename from src/es_archiver/actions/save.js
rename to src/es_archiver/actions/save.ts
index 2c264ed2ee3a9..7a3a9dd97c0ab 100644
--- a/src/es_archiver/actions/save.js
+++ b/src/es_archiver/actions/save.ts
@@ -19,9 +19,11 @@
 
 import { resolve } from 'path';
 import { createWriteStream, mkdirSync } from 'fs';
+import { Readable, Writable } from 'stream';
+import { Client } from 'elasticsearch';
+import { ToolingLog } from '@kbn/dev-utils';
 
 import { createListStream, createPromiseFromStreams } from '../../legacy/utils';
-
 import {
   createStats,
   createGenerateIndexRecordsStream,
@@ -30,7 +32,21 @@ import {
   Progress,
 } from '../lib';
 
-export async function saveAction({ name, indices, client, dataDir, log, raw }) {
+export async function saveAction({
+  name,
+  indices,
+  client,
+  dataDir,
+  log,
+  raw,
+}: {
+  name: string;
+  indices: string | string[];
+  client: Client;
+  dataDir: string;
+  log: ToolingLog;
+  raw: boolean;
+}) {
   const outputDir = resolve(dataDir, name);
   const stats = createStats(name, log);
 
@@ -48,7 +64,7 @@ export async function saveAction({ name, indices, client, dataDir, log, raw }) {
       createGenerateIndexRecordsStream(client, stats),
       ...createFormatArchiveStreams(),
       createWriteStream(resolve(outputDir, 'mappings.json')),
-    ]),
+    ] as [Readable, ...Writable[]]),
 
     // export all documents from matching indexes into data.json.gz
     createPromiseFromStreams([
@@ -56,7 +72,7 @@ export async function saveAction({ name, indices, client, dataDir, log, raw }) {
       createGenerateDocRecordsStream(client, stats, progress),
       ...createFormatArchiveStreams({ gzip: !raw }),
       createWriteStream(resolve(outputDir, `data.json${raw ? '' : '.gz'}`)),
-    ]),
+    ] as [Readable, ...Writable[]]),
   ]);
 
   progress.deactivate();
diff --git a/src/es_archiver/actions/unload.js b/src/es_archiver/actions/unload.ts
similarity index 79%
rename from src/es_archiver/actions/unload.js
rename to src/es_archiver/actions/unload.ts
index 2acf8d2d71986..130a6b542b218 100644
--- a/src/es_archiver/actions/unload.js
+++ b/src/es_archiver/actions/unload.ts
@@ -19,9 +19,11 @@
 
 import { resolve } from 'path';
 import { createReadStream } from 'fs';
+import { Readable, Writable } from 'stream';
+import { Client } from 'elasticsearch';
+import { ToolingLog, KbnClient } from '@kbn/dev-utils';
 
 import { createPromiseFromStreams } from '../../legacy/utils';
-
 import {
   isGzip,
   createStats,
@@ -32,7 +34,19 @@ import {
   createDeleteIndexStream,
 } from '../lib';
 
-export async function unloadAction({ name, client, dataDir, log, kbnClient }) {
+export async function unloadAction({
+  name,
+  client,
+  dataDir,
+  log,
+  kbnClient,
+}: {
+  name: string;
+  client: Client;
+  dataDir: string;
+  log: ToolingLog;
+  kbnClient: KbnClient;
+}) {
   const inputDir = resolve(dataDir, name);
   const stats = createStats(name, log);
   const kibanaPluginIds = await kbnClient.plugins.getEnabledIds();
@@ -42,11 +56,11 @@ export async function unloadAction({ name, client, dataDir, log, kbnClient }) {
     log.info('[%s] Unloading indices from %j', name, filename);
 
     await createPromiseFromStreams([
-      createReadStream(resolve(inputDir, filename)),
+      createReadStream(resolve(inputDir, filename)) as Readable,
       ...createParseArchiveStreams({ gzip: isGzip(filename) }),
       createFilterRecordsStream('index'),
       createDeleteIndexStream(client, stats, log, kibanaPluginIds),
-    ]);
+    ] as [Readable, ...Writable[]]);
   }
 
   return stats.toJSON();
diff --git a/src/es_archiver/cli.js b/src/es_archiver/cli.ts
similarity index 90%
rename from src/es_archiver/cli.js
rename to src/es_archiver/cli.ts
index 56d1fdca89780..252f99f8f47af 100644
--- a/src/es_archiver/cli.js
+++ b/src/es_archiver/cli.ts
@@ -17,7 +17,7 @@
  * under the License.
  */
 
-/*************************************************************
+/** ***********************************************************
  *
  *  Run `node scripts/es_archiver --help` for usage information
  *
@@ -27,17 +27,17 @@ import { resolve } from 'path';
 import { readFileSync } from 'fs';
 import { format as formatUrl } from 'url';
 import readline from 'readline';
-
 import { Command } from 'commander';
 import * as legacyElasticsearch from 'elasticsearch';
 
-import { EsArchiver } from './es_archiver';
 import { ToolingLog } from '@kbn/dev-utils';
 import { readConfigFile } from '@kbn/test';
 
+import { EsArchiver } from './es_archiver';
+
 const cmd = new Command('node scripts/es_archiver');
 
-const resolveConfigPath = v => resolve(process.cwd(), v);
+const resolveConfigPath = (v: string) => resolve(process.cwd(), v);
 const defaultConfigPath = resolveConfigPath('test/functional/config.js');
 
 cmd
@@ -56,6 +56,7 @@ cmd
     defaultConfigPath
   )
   .on('--help', () => {
+    // eslint-disable-next-line no-console
     console.log(readFileSync(resolve(__dirname, './cli_help.txt'), 'utf8'));
   });
 
@@ -95,10 +96,10 @@ cmd
           output: process.stdout,
         });
 
-        await new Promise(resolve => {
+        await new Promise(resolveInput => {
           rl.question(`Press enter when you're done`, () => {
             rl.close();
-            resolve();
+            resolveInput();
           });
         });
       })
@@ -112,12 +113,12 @@ cmd
 
 cmd.parse(process.argv);
 
-const missingCommand = cmd.args.every(a => !(a instanceof Command));
+const missingCommand = cmd.args.every(a => !((a as any) instanceof Command));
 if (missingCommand) {
   execute();
 }
 
-async function execute(fn) {
+async function execute(fn?: (esArchiver: EsArchiver, command: Command) => void): Promise<void> {
   try {
     const log = new ToolingLog({
       level: cmd.verbose ? 'debug' : 'info',
@@ -134,7 +135,7 @@ async function execute(fn) {
 
     // log and count all validation errors
     let errorCount = 0;
-    const error = msg => {
+    const error = (msg: string) => {
       errorCount++;
       log.error(msg);
     };
@@ -170,11 +171,12 @@ async function execute(fn) {
         dataDir: resolve(cmd.dir),
         kibanaUrl: cmd.kibanaUrl,
       });
-      await fn(esArchiver, cmd);
+      await fn!(esArchiver, cmd);
     } finally {
       await client.close();
     }
   } catch (err) {
+    // eslint-disable-next-line no-console
     console.log('FATAL ERROR', err.stack);
   }
 }
diff --git a/src/es_archiver/es_archiver.d.ts b/src/es_archiver/es_archiver.d.ts
deleted file mode 100644
index c50ae19d99cbf..0000000000000
--- a/src/es_archiver/es_archiver.d.ts
+++ /dev/null
@@ -1,39 +0,0 @@
-/*
- * Licensed to Elasticsearch B.V. under one or more contributor
- * license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright
- * ownership. Elasticsearch B.V. licenses this file to you under
- * the Apache License, Version 2.0 (the "License"); you may
- * not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-
-import { ToolingLog } from '@kbn/dev-utils';
-import { Client } from 'elasticsearch';
-import { createStats } from './lib/stats';
-
-export type JsonStats = ReturnType<ReturnType<typeof createStats>['toJSON']>;
-
-export class EsArchiver {
-  constructor(options: { client: Client; dataDir: string; log: ToolingLog; kibanaUrl: string });
-  public save(
-    name: string,
-    indices: string | string[],
-    options?: { raw?: boolean }
-  ): Promise<JsonStats>;
-  public load(name: string, options?: { skipExisting?: boolean }): Promise<JsonStats>;
-  public unload(name: string): Promise<JsonStats>;
-  public rebuildAll(): Promise<void>;
-  public edit(prefix: string, handler: () => Promise<void>): Promise<void>;
-  public loadIfNeeded(name: string): Promise<JsonStats>;
-  public emptyKibanaIndex(): Promise<JsonStats>;
-}
diff --git a/src/es_archiver/es_archiver.js b/src/es_archiver/es_archiver.ts
similarity index 83%
rename from src/es_archiver/es_archiver.js
rename to src/es_archiver/es_archiver.ts
index 705706d0e5877..5614dfd842087 100644
--- a/src/es_archiver/es_archiver.js
+++ b/src/es_archiver/es_archiver.ts
@@ -17,7 +17,8 @@
  * under the License.
  */
 
-import { KbnClient } from '@kbn/dev-utils';
+import { Client } from 'elasticsearch';
+import { ToolingLog, KbnClient } from '@kbn/dev-utils';
 
 import {
   saveAction,
@@ -29,7 +30,22 @@ import {
 } from './actions';
 
 export class EsArchiver {
-  constructor({ client, dataDir, log, kibanaUrl }) {
+  private readonly client: Client;
+  private readonly dataDir: string;
+  private readonly log: ToolingLog;
+  private readonly kbnClient: KbnClient;
+
+  constructor({
+    client,
+    dataDir,
+    log,
+    kibanaUrl,
+  }: {
+    client: Client;
+    dataDir: string;
+    log: ToolingLog;
+    kibanaUrl: string;
+  }) {
     this.client = client;
     this.dataDir = dataDir;
     this.log = log;
@@ -46,7 +62,7 @@ export class EsArchiver {
    *  @property {Boolean} options.raw - should the archive be raw (unzipped) or not
    *  @return Promise<Stats>
    */
-  async save(name, indices, { raw = false } = {}) {
+  async save(name: string, indices: string | string[], { raw = false }: { raw?: boolean } = {}) {
     return await saveAction({
       name,
       indices,
@@ -66,9 +82,7 @@ export class EsArchiver {
    *                                           be ignored or overwritten
    *  @return Promise<Stats>
    */
-  async load(name, options = {}) {
-    const { skipExisting } = options;
-
+  async load(name: string, { skipExisting = false }: { skipExisting?: boolean } = {}) {
     return await loadAction({
       name,
       skipExisting: !!skipExisting,
@@ -85,7 +99,7 @@ export class EsArchiver {
    *  @param {String} name
    *  @return Promise<Stats>
    */
-  async unload(name) {
+  async unload(name: string) {
     return await unloadAction({
       name,
       client: this.client,
@@ -103,7 +117,6 @@ export class EsArchiver {
    */
   async rebuildAll() {
     return await rebuildAllAction({
-      client: this.client,
       dataDir: this.dataDir,
       log: this.log,
     });
@@ -117,7 +130,7 @@ export class EsArchiver {
    *  @param {() => Promise<any>} handler
    *  @return Promise<void>
    */
-  async edit(prefix, handler) {
+  async edit(prefix: string, handler: () => Promise<void>) {
     return await editAction({
       prefix,
       log: this.log,
@@ -132,7 +145,7 @@ export class EsArchiver {
    *  @param {String} name
    *  @return Promise<Stats>
    */
-  async loadIfNeeded(name) {
+  async loadIfNeeded(name: string) {
     return await this.load(name, { skipExisting: true });
   }
 
diff --git a/src/es_archiver/index.js b/src/es_archiver/index.js
deleted file mode 100644
index f7a579a98a42d..0000000000000
--- a/src/es_archiver/index.js
+++ /dev/null
@@ -1,20 +0,0 @@
-/*
- * Licensed to Elasticsearch B.V. under one or more contributor
- * license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright
- * ownership. Elasticsearch B.V. licenses this file to you under
- * the Apache License, Version 2.0 (the "License"); you may
- * not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-
-export { EsArchiver } from './es_archiver';
diff --git a/src/es_archiver/index.d.ts b/src/es_archiver/index.ts
similarity index 100%
rename from src/es_archiver/index.d.ts
rename to src/es_archiver/index.ts
diff --git a/src/es_archiver/lib/__tests__/stats.js b/src/es_archiver/lib/__tests__/stats.ts
similarity index 95%
rename from src/es_archiver/lib/__tests__/stats.js
rename to src/es_archiver/lib/__tests__/stats.ts
index ccc24c25fb860..28e337b3da529 100644
--- a/src/es_archiver/lib/__tests__/stats.js
+++ b/src/es_archiver/lib/__tests__/stats.ts
@@ -17,26 +17,26 @@
  * under the License.
  */
 
-import expect from '@kbn/expect';
 import { uniq } from 'lodash';
 import sinon from 'sinon';
+import expect from '@kbn/expect';
+import { ToolingLog } from '@kbn/dev-utils';
 
 import { createStats } from '../';
-import { ToolingLog } from '@kbn/dev-utils';
 
-function createBufferedLog() {
-  const log = new ToolingLog({
+function createBufferedLog(): ToolingLog & { buffer: string } {
+  const log: ToolingLog = new ToolingLog({
     level: 'debug',
     writeTo: {
-      write: chunk => (log.buffer += chunk),
+      write: chunk => ((log as any).buffer += chunk),
     },
   });
-  log.buffer = '';
-  return log;
+  (log as any).buffer = '';
+  return log as ToolingLog & { buffer: string };
 }
 
-function assertDeepClones(a, b) {
-  const path = [];
+function assertDeepClones(a: any, b: any) {
+  const path: string[] = [];
   try {
     (function recurse(one, two) {
       if (typeof one !== 'object' || typeof two !== 'object') {
diff --git a/src/es_archiver/lib/archives/__tests__/format.js b/src/es_archiver/lib/archives/__tests__/format.ts
similarity index 89%
rename from src/es_archiver/lib/archives/__tests__/format.js
rename to src/es_archiver/lib/archives/__tests__/format.ts
index 20ead30824d06..f472f094134d7 100644
--- a/src/es_archiver/lib/archives/__tests__/format.js
+++ b/src/es_archiver/lib/archives/__tests__/format.ts
@@ -17,7 +17,7 @@
  * under the License.
  */
 
-import Stream from 'stream';
+import Stream, { Readable, Writable } from 'stream';
 import { createGunzip } from 'zlib';
 
 import expect from '@kbn/expect';
@@ -43,11 +43,11 @@ describe('esArchiver createFormatArchiveStreams', () => {
     });
 
     it('streams consume js values and produces buffers', async () => {
-      const output = await createPromiseFromStreams([
+      const output = await createPromiseFromStreams<Buffer[]>([
         createListStream(INPUTS),
         ...createFormatArchiveStreams({ gzip: false }),
         createConcatStream([]),
-      ]);
+      ] as [Readable, ...Writable[]]);
 
       expect(output.length).to.be.greaterThan(0);
       output.forEach(b => expect(b).to.be.a(Buffer));
@@ -58,7 +58,7 @@ describe('esArchiver createFormatArchiveStreams', () => {
         createListStream(INPUTS),
         ...createFormatArchiveStreams({ gzip: false }),
         createConcatStream(''),
-      ]);
+      ] as [Readable, ...Writable[]]);
 
       expect(json).to.be(INPUT_JSON);
     });
@@ -73,11 +73,11 @@ describe('esArchiver createFormatArchiveStreams', () => {
     });
 
     it('streams consume js values and produces buffers', async () => {
-      const output = await createPromiseFromStreams([
+      const output = await createPromiseFromStreams<Buffer[]>([
         createListStream([1, 2, { foo: 'bar' }, [1, 2]]),
         ...createFormatArchiveStreams({ gzip: true }),
         createConcatStream([]),
-      ]);
+      ] as [Readable, ...Writable[]]);
 
       expect(output.length).to.be.greaterThan(0);
       output.forEach(b => expect(b).to.be.a(Buffer));
@@ -89,7 +89,7 @@ describe('esArchiver createFormatArchiveStreams', () => {
         ...createFormatArchiveStreams({ gzip: true }),
         createGunzip(),
         createConcatStream(''),
-      ]);
+      ] as [Readable, ...Writable[]]);
       expect(output).to.be(INPUT_JSON);
     });
   });
@@ -100,7 +100,7 @@ describe('esArchiver createFormatArchiveStreams', () => {
         createListStream(INPUTS),
         ...createFormatArchiveStreams(),
         createConcatStream(''),
-      ]);
+      ] as [Readable, ...Writable[]]);
 
       expect(json).to.be(INPUT_JSON);
     });
diff --git a/src/es_archiver/lib/archives/__tests__/parse.js b/src/es_archiver/lib/archives/__tests__/parse.ts
similarity index 93%
rename from src/es_archiver/lib/archives/__tests__/parse.js
rename to src/es_archiver/lib/archives/__tests__/parse.ts
index 2e1506e543a35..ba30156b5af39 100644
--- a/src/es_archiver/lib/archives/__tests__/parse.js
+++ b/src/es_archiver/lib/archives/__tests__/parse.ts
@@ -17,7 +17,7 @@
  * under the License.
  */
 
-import Stream, { PassThrough, Transform } from 'stream';
+import Stream, { PassThrough, Readable, Writable, Transform } from 'stream';
 import { createGzip } from 'zlib';
 
 import expect from '@kbn/expect';
@@ -66,13 +66,13 @@ describe('esArchiver createParseArchiveStreams', () => {
           ]),
           ...createParseArchiveStreams({ gzip: false }),
           createConcatStream([]),
-        ]);
+        ] as [Readable, ...Writable[]]);
 
         expect(output).to.eql([{ a: 1 }, 1]);
       });
 
       it('provides each JSON object as soon as it is parsed', async () => {
-        let onReceived;
+        let onReceived: (resolved: any) => void;
         const receivedPromise = new Promise(resolve => (onReceived = resolve));
         const input = new PassThrough();
         const check = new Transform({
@@ -80,16 +80,16 @@ describe('esArchiver createParseArchiveStreams', () => {
           readableObjectMode: true,
           transform(chunk, env, callback) {
             onReceived(chunk);
-            callback(null, chunk);
+            callback(undefined, chunk);
           },
         });
 
         const finalPromise = createPromiseFromStreams([
-          input,
+          input as Readable,
           ...createParseArchiveStreams(),
           check,
           createConcatStream([]),
-        ]);
+        ] as [Readable, ...Writable[]]);
 
         input.write(Buffer.from('{"a": 1}\n\n{"a":'));
         expect(await receivedPromise).to.eql({ a: 1 });
@@ -110,7 +110,7 @@ describe('esArchiver createParseArchiveStreams', () => {
             ]),
             ...createParseArchiveStreams({ gzip: false }),
             createConcatStream(),
-          ]);
+          ] as [Readable, ...Writable[]]);
           throw new Error('should have failed');
         } catch (err) {
           expect(err.message).to.contain('Unexpected number');
@@ -149,7 +149,7 @@ describe('esArchiver createParseArchiveStreams', () => {
           createGzip(),
           ...createParseArchiveStreams({ gzip: true }),
           createConcatStream([]),
-        ]);
+        ] as [Readable, ...Writable[]]);
 
         expect(output).to.eql([{ a: 1 }, { a: 2 }]);
       });
@@ -161,7 +161,7 @@ describe('esArchiver createParseArchiveStreams', () => {
         createGzip(),
         ...createParseArchiveStreams({ gzip: true }),
         createConcatStream([]),
-      ]);
+      ] as [Readable, ...Writable[]]);
 
       expect(output).to.eql([]);
     });
@@ -173,7 +173,7 @@ describe('esArchiver createParseArchiveStreams', () => {
             createListStream([Buffer.from('{"a": 1}')]),
             ...createParseArchiveStreams({ gzip: true }),
             createConcatStream(),
-          ]);
+          ] as [Readable, ...Writable[]]);
           throw new Error('should have failed');
         } catch (err) {
           expect(err.message).to.contain('incorrect header check');
diff --git a/src/es_archiver/lib/archives/constants.js b/src/es_archiver/lib/archives/constants.ts
similarity index 100%
rename from src/es_archiver/lib/archives/constants.js
rename to src/es_archiver/lib/archives/constants.ts
diff --git a/src/es_archiver/lib/archives/filenames.js b/src/es_archiver/lib/archives/filenames.ts
similarity index 91%
rename from src/es_archiver/lib/archives/filenames.js
rename to src/es_archiver/lib/archives/filenames.ts
index 4ced04401d28d..24c355edda278 100644
--- a/src/es_archiver/lib/archives/filenames.js
+++ b/src/es_archiver/lib/archives/filenames.ts
@@ -19,7 +19,7 @@
 
 import { basename, extname } from 'path';
 
-export function isGzip(path) {
+export function isGzip(path: string) {
   return extname(path) === '.gz';
 }
 
@@ -28,7 +28,7 @@ export function isGzip(path) {
  *  @param  {String} path
  *  @return {Boolean}
  */
-export function isMappingFile(path) {
+export function isMappingFile(path: string) {
   return basename(path, '.gz') === 'mappings.json';
 }
 
@@ -41,7 +41,7 @@ export function isMappingFile(path) {
  *  @param {Array<String>} filenames
  *  @return {Array<String>}
  */
-export function prioritizeMappings(filenames) {
+export function prioritizeMappings(filenames: string[]) {
   return filenames.slice().sort((fa, fb) => {
     if (isMappingFile(fa) === isMappingFile(fb)) return 0;
     return isMappingFile(fb) ? 1 : -1;
diff --git a/src/es_archiver/lib/archives/format.js b/src/es_archiver/lib/archives/format.ts
similarity index 93%
rename from src/es_archiver/lib/archives/format.js
rename to src/es_archiver/lib/archives/format.ts
index 01fca87e7ba98..9bef4c9adbf05 100644
--- a/src/es_archiver/lib/archives/format.js
+++ b/src/es_archiver/lib/archives/format.ts
@@ -19,14 +19,12 @@
 
 import { createGzip, Z_BEST_COMPRESSION } from 'zlib';
 import { PassThrough } from 'stream';
-
 import stringify from 'json-stable-stringify';
 
 import { createMapStream, createIntersperseStream } from '../../../legacy/utils';
-
 import { RECORD_SEPARATOR } from './constants';
 
-export function createFormatArchiveStreams({ gzip = false } = {}) {
+export function createFormatArchiveStreams({ gzip = false }: { gzip?: boolean } = {}) {
   return [
     createMapStream(record => stringify(record, { space: '  ' })),
     createIntersperseStream(RECORD_SEPARATOR),
diff --git a/src/es_archiver/lib/archives/index.js b/src/es_archiver/lib/archives/index.ts
similarity index 99%
rename from src/es_archiver/lib/archives/index.js
rename to src/es_archiver/lib/archives/index.ts
index 4020f52e45a35..6aa489ea5a46d 100644
--- a/src/es_archiver/lib/archives/index.js
+++ b/src/es_archiver/lib/archives/index.ts
@@ -18,7 +18,5 @@
  */
 
 export { isGzip, prioritizeMappings } from './filenames';
-
 export { createParseArchiveStreams } from './parse';
-
 export { createFormatArchiveStreams } from './format';
diff --git a/src/es_archiver/lib/archives/parse.js b/src/es_archiver/lib/archives/parse.ts
similarity index 91%
rename from src/es_archiver/lib/archives/parse.js
rename to src/es_archiver/lib/archives/parse.ts
index 4fe1df7259229..0f4460c925019 100644
--- a/src/es_archiver/lib/archives/parse.js
+++ b/src/es_archiver/lib/archives/parse.ts
@@ -29,7 +29,7 @@ export function createParseArchiveStreams({ gzip = false } = {}) {
     gzip ? createGunzip() : new PassThrough(),
     createReplaceStream('\r\n', '\n'),
     createSplitStream(RECORD_SEPARATOR),
-    createFilterStream(l => l.match(/[^\s]/)),
-    createMapStream(json => JSON.parse(json.trim())),
+    createFilterStream<string>(l => !!l.match(/[^\s]/)),
+    createMapStream<string>(json => JSON.parse(json.trim())),
   ];
 }
diff --git a/src/es_archiver/lib/directory.js b/src/es_archiver/lib/directory.ts
similarity index 88%
rename from src/es_archiver/lib/directory.js
rename to src/es_archiver/lib/directory.ts
index 5aee10cfea65d..8581207fa795d 100644
--- a/src/es_archiver/lib/directory.js
+++ b/src/es_archiver/lib/directory.ts
@@ -18,10 +18,9 @@
  */
 
 import { readdir } from 'fs';
-
 import { fromNode } from 'bluebird';
 
-export async function readDirectory(path) {
-  const allNames = await fromNode(cb => readdir(path, cb));
+export async function readDirectory(path: string) {
+  const allNames = await fromNode<string[]>(cb => readdir(path, cb));
   return allNames.filter(name => !name.startsWith('.'));
 }
diff --git a/src/es_archiver/lib/docs/__tests__/generate_doc_records_stream.js b/src/es_archiver/lib/docs/__tests__/generate_doc_records_stream.ts
similarity index 98%
rename from src/es_archiver/lib/docs/__tests__/generate_doc_records_stream.js
rename to src/es_archiver/lib/docs/__tests__/generate_doc_records_stream.ts
index bf4aab208127f..03599cdc9fbcf 100644
--- a/src/es_archiver/lib/docs/__tests__/generate_doc_records_stream.js
+++ b/src/es_archiver/lib/docs/__tests__/generate_doc_records_stream.ts
@@ -143,7 +143,7 @@ describe('esArchiver: createGenerateDocRecordsStream()', () => {
         },
       },
     ]);
-    sinon.assert.calledTwice(stats.archivedDoc);
+    sinon.assert.calledTwice(stats.archivedDoc as any);
     expect(progress.getTotal()).to.be(2);
     expect(progress.getComplete()).to.be(2);
   });
diff --git a/src/es_archiver/lib/docs/__tests__/index_doc_records_stream.js b/src/es_archiver/lib/docs/__tests__/index_doc_records_stream.ts
similarity index 98%
rename from src/es_archiver/lib/docs/__tests__/index_doc_records_stream.js
rename to src/es_archiver/lib/docs/__tests__/index_doc_records_stream.ts
index 2535642c27cc9..35b068a691090 100644
--- a/src/es_archiver/lib/docs/__tests__/index_doc_records_stream.js
+++ b/src/es_archiver/lib/docs/__tests__/index_doc_records_stream.ts
@@ -26,12 +26,12 @@ import { Progress } from '../../progress';
 import { createIndexDocRecordsStream } from '../index_doc_records_stream';
 import { createStubStats, createStubClient, createPersonDocRecords } from './stubs';
 
-const recordsToBulkBody = records => {
+const recordsToBulkBody = (records: any[]) => {
   return records.reduce((acc, record) => {
     const { index, id, source } = record.value;
 
     return [...acc, { index: { _index: index, _id: id } }, source];
-  }, []);
+  }, [] as any[]);
 };
 
 describe('esArchiver: createIndexDocRecordsStream()', () => {
diff --git a/src/es_archiver/lib/docs/__tests__/stubs.js b/src/es_archiver/lib/docs/__tests__/stubs.ts
similarity index 74%
rename from src/es_archiver/lib/docs/__tests__/stubs.js
rename to src/es_archiver/lib/docs/__tests__/stubs.ts
index 9ed48efa7d03a..698d62e450cb4 100644
--- a/src/es_archiver/lib/docs/__tests__/stubs.js
+++ b/src/es_archiver/lib/docs/__tests__/stubs.ts
@@ -17,17 +17,22 @@
  * under the License.
  */
 
+import { Client } from 'elasticsearch';
 import sinon from 'sinon';
 import Chance from 'chance';
 import { times } from 'lodash';
+
+import { Stats } from '../../stats';
+
 const chance = new Chance();
 
-export const createStubStats = () => ({
-  indexedDoc: sinon.stub(),
-  archivedDoc: sinon.stub(),
-});
+export const createStubStats = (): Stats =>
+  ({
+    indexedDoc: sinon.stub(),
+    archivedDoc: sinon.stub(),
+  } as any);
 
-export const createPersonDocRecords = n =>
+export const createPersonDocRecords = (n: number) =>
   times(n, () => ({
     type: 'doc',
     value: {
@@ -42,15 +47,21 @@ export const createPersonDocRecords = n =>
     },
   }));
 
-export const createStubClient = (responses = []) => {
-  const createStubClientMethod = name =>
+type MockClient = Client & {
+  assertNoPendingResponses: () => void;
+};
+
+export const createStubClient = (
+  responses: Array<(name: string, params: any) => any | Promise<any>> = []
+): MockClient => {
+  const createStubClientMethod = (name: string) =>
     sinon.spy(async params => {
       if (responses.length === 0) {
         throw new Error(`unexpected client.${name} call`);
       }
 
       const response = responses.shift();
-      return await response(name, params);
+      return await response!(name, params);
     });
 
   return {
@@ -63,5 +74,5 @@ export const createStubClient = (responses = []) => {
         throw new Error(`There are ${responses.length} unsent responses.`);
       }
     },
-  };
+  } as any;
 };
diff --git a/src/es_archiver/lib/docs/generate_doc_records_stream.js b/src/es_archiver/lib/docs/generate_doc_records_stream.ts
similarity index 80%
rename from src/es_archiver/lib/docs/generate_doc_records_stream.js
rename to src/es_archiver/lib/docs/generate_doc_records_stream.ts
index be8b0351d95c8..e255a0abc36c5 100644
--- a/src/es_archiver/lib/docs/generate_doc_records_stream.js
+++ b/src/es_archiver/lib/docs/generate_doc_records_stream.ts
@@ -18,33 +18,36 @@
  */
 
 import { Transform } from 'stream';
+import { Client, SearchParams, SearchResponse } from 'elasticsearch';
+import { Stats } from '../stats';
+import { Progress } from '../progress';
 
 const SCROLL_SIZE = 1000;
 const SCROLL_TIMEOUT = '1m';
 
-export function createGenerateDocRecordsStream(client, stats, progress) {
+export function createGenerateDocRecordsStream(client: Client, stats: Stats, progress: Progress) {
   return new Transform({
     writableObjectMode: true,
     readableObjectMode: true,
     async transform(index, enc, callback) {
       try {
-        let remainingHits = null;
-        let resp = null;
+        let remainingHits = 0;
+        let resp: SearchResponse<any> | null = null;
 
         while (!resp || remainingHits > 0) {
           if (!resp) {
             resp = await client.search({
-              index: index,
+              index,
               scroll: SCROLL_TIMEOUT,
               size: SCROLL_SIZE,
               _source: true,
-              rest_total_hits_as_int: true,
-            });
+              rest_total_hits_as_int: true, // not declared on SearchParams type
+            } as SearchParams);
             remainingHits = resp.hits.total;
             progress.addToTotal(remainingHits);
           } else {
             resp = await client.scroll({
-              scrollId: resp._scroll_id,
+              scrollId: resp._scroll_id!,
               scroll: SCROLL_TIMEOUT,
             });
           }
@@ -68,7 +71,7 @@ export function createGenerateDocRecordsStream(client, stats, progress) {
           progress.addToComplete(resp.hits.hits.length);
         }
 
-        callback(null);
+        callback(undefined);
       } catch (err) {
         callback(err);
       }
diff --git a/src/es_archiver/lib/docs/index.js b/src/es_archiver/lib/docs/index.ts
similarity index 100%
rename from src/es_archiver/lib/docs/index.js
rename to src/es_archiver/lib/docs/index.ts
diff --git a/src/es_archiver/lib/docs/index_doc_records_stream.js b/src/es_archiver/lib/docs/index_doc_records_stream.ts
similarity index 86%
rename from src/es_archiver/lib/docs/index_doc_records_stream.js
rename to src/es_archiver/lib/docs/index_doc_records_stream.ts
index 73fb75c52ff0a..8236ae8adb6db 100644
--- a/src/es_archiver/lib/docs/index_doc_records_stream.js
+++ b/src/es_archiver/lib/docs/index_doc_records_stream.ts
@@ -17,11 +17,14 @@
  * under the License.
  */
 
+import { Client } from 'elasticsearch';
 import { Writable } from 'stream';
+import { Stats } from '../stats';
+import { Progress } from '../progress';
 
-export function createIndexDocRecordsStream(client, stats, progress) {
-  async function indexDocs(docs) {
-    const body = [];
+export function createIndexDocRecordsStream(client: Client, stats: Stats, progress: Progress) {
+  async function indexDocs(docs: any[]) {
+    const body: any[] = [];
 
     docs.forEach(doc => {
       stats.indexedDoc(doc.index);
diff --git a/src/es_archiver/lib/index.js b/src/es_archiver/lib/index.ts
similarity index 96%
rename from src/es_archiver/lib/index.js
rename to src/es_archiver/lib/index.ts
index 246dd8169cd6b..960d51e411859 100644
--- a/src/es_archiver/lib/index.js
+++ b/src/es_archiver/lib/index.ts
@@ -30,7 +30,7 @@ export {
 
 export { createFilterRecordsStream } from './records';
 
-export { createStats } from './stats';
+export { createStats, Stats } from './stats';
 
 export {
   isGzip,
diff --git a/src/es_archiver/lib/indices/__tests__/create_index_stream.js b/src/es_archiver/lib/indices/__tests__/create_index_stream.ts
similarity index 76%
rename from src/es_archiver/lib/indices/__tests__/create_index_stream.js
rename to src/es_archiver/lib/indices/__tests__/create_index_stream.ts
index 9e0f83c9f7eb9..c90497eded88c 100644
--- a/src/es_archiver/lib/indices/__tests__/create_index_stream.js
+++ b/src/es_archiver/lib/indices/__tests__/create_index_stream.ts
@@ -34,10 +34,13 @@ import {
   createStubIndexRecord,
   createStubDocRecord,
   createStubClient,
+  createStubLogger,
 } from './stubs';
 
 const chance = new Chance();
 
+const log = createStubLogger();
+
 describe('esArchiver: createCreateIndexStream()', () => {
   describe('defaults', () => {
     it('deletes existing indices, creates all', async () => {
@@ -48,15 +51,15 @@ describe('esArchiver: createCreateIndexStream()', () => {
           createStubIndexRecord('existing-index'),
           createStubIndexRecord('new-index'),
         ]),
-        createCreateIndexStream({ client, stats }),
+        createCreateIndexStream({ client, stats, log }),
       ]);
 
       expect(stats.getTestSummary()).to.eql({
         deletedIndex: 1,
         createdIndex: 2,
       });
-      sinon.assert.callCount(client.indices.delete, 1);
-      sinon.assert.callCount(client.indices.create, 3); // one failed create because of existing
+      sinon.assert.callCount(client.indices.delete as sinon.SinonSpy, 1);
+      sinon.assert.callCount(client.indices.create as sinon.SinonSpy, 3); // one failed create because of existing
     });
 
     it('deletes existing aliases, creates all', async () => {
@@ -67,14 +70,19 @@ describe('esArchiver: createCreateIndexStream()', () => {
           createStubIndexRecord('existing-index'),
           createStubIndexRecord('new-index'),
         ]),
-        createCreateIndexStream({ client, stats, log: { debug: () => {} } }),
+        createCreateIndexStream({ client, stats, log }),
       ]);
 
-      expect(client.indices.getAlias.calledOnce).to.be.ok();
-      expect(client.indices.getAlias.args[0][0]).to.eql({ name: 'existing-index', ignore: [404] });
-      expect(client.indices.delete.calledOnce).to.be.ok();
-      expect(client.indices.delete.args[0][0]).to.eql({ index: ['actual-index'] });
-      sinon.assert.callCount(client.indices.create, 3); // one failed create because of existing
+      expect((client.indices.getAlias as sinon.SinonSpy).calledOnce).to.be.ok();
+      expect((client.indices.getAlias as sinon.SinonSpy).args[0][0]).to.eql({
+        name: 'existing-index',
+        ignore: [404],
+      });
+      expect((client.indices.delete as sinon.SinonSpy).calledOnce).to.be.ok();
+      expect((client.indices.delete as sinon.SinonSpy).args[0][0]).to.eql({
+        index: ['actual-index'],
+      });
+      sinon.assert.callCount(client.indices.create as sinon.SinonSpy, 3); // one failed create because of existing
     });
 
     it('passes through "hit" records', async () => {
@@ -86,7 +94,7 @@ describe('esArchiver: createCreateIndexStream()', () => {
           createStubDocRecord('index', 1),
           createStubDocRecord('index', 2),
         ]),
-        createCreateIndexStream({ client, stats }),
+        createCreateIndexStream({ client, stats, log }),
         createConcatStream([]),
       ]);
 
@@ -101,11 +109,11 @@ describe('esArchiver: createCreateIndexStream()', () => {
           createStubIndexRecord('index', { foo: {} }),
           createStubDocRecord('index', 1),
         ]),
-        createCreateIndexStream({ client, stats }),
+        createCreateIndexStream({ client, stats, log }),
         createConcatStream([]),
       ]);
 
-      sinon.assert.calledWith(client.indices.create, {
+      sinon.assert.calledWith(client.indices.create as sinon.SinonSpy, {
         method: 'PUT',
         index: 'index',
         body: {
@@ -126,7 +134,7 @@ describe('esArchiver: createCreateIndexStream()', () => {
 
       const output = await createPromiseFromStreams([
         createListStream([createStubIndexRecord('index'), ...randoms]),
-        createCreateIndexStream({ client, stats }),
+        createCreateIndexStream({ client, stats, log }),
         createConcatStream([]),
       ]);
 
@@ -140,7 +148,7 @@ describe('esArchiver: createCreateIndexStream()', () => {
 
       const output = await createPromiseFromStreams([
         createListStream(nonRecordValues),
-        createCreateIndexStream({ client, stats }),
+        createCreateIndexStream({ client, stats, log }),
         createConcatStream([]),
       ]);
 
@@ -161,6 +169,7 @@ describe('esArchiver: createCreateIndexStream()', () => {
         createCreateIndexStream({
           client,
           stats,
+          log,
           skipExisting: true,
         }),
       ]);
@@ -169,9 +178,12 @@ describe('esArchiver: createCreateIndexStream()', () => {
         skippedIndex: 1,
         createdIndex: 1,
       });
-      sinon.assert.callCount(client.indices.delete, 0);
-      sinon.assert.callCount(client.indices.create, 2); // one failed create because of existing
-      expect(client.indices.create.args[0][0]).to.have.property('index', 'new-index');
+      sinon.assert.callCount(client.indices.delete as sinon.SinonSpy, 0);
+      sinon.assert.callCount(client.indices.create as sinon.SinonSpy, 2); // one failed create because of existing
+      expect((client.indices.create as sinon.SinonSpy).args[0][0]).to.have.property(
+        'index',
+        'new-index'
+      );
     });
 
     it('filters documents for skipped indices', async () => {
@@ -190,6 +202,7 @@ describe('esArchiver: createCreateIndexStream()', () => {
         createCreateIndexStream({
           client,
           stats,
+          log,
           skipExisting: true,
         }),
         createConcatStream([]),
@@ -199,8 +212,8 @@ describe('esArchiver: createCreateIndexStream()', () => {
         skippedIndex: 1,
         createdIndex: 1,
       });
-      sinon.assert.callCount(client.indices.delete, 0);
-      sinon.assert.callCount(client.indices.create, 2); // one failed create because of existing
+      sinon.assert.callCount(client.indices.delete as sinon.SinonSpy, 0);
+      sinon.assert.callCount(client.indices.create as sinon.SinonSpy, 2); // one failed create because of existing
 
       expect(output).to.have.length(2);
       expect(output).to.eql([
diff --git a/src/es_archiver/lib/indices/__tests__/delete_index_stream.js b/src/es_archiver/lib/indices/__tests__/delete_index_stream.ts
similarity index 66%
rename from src/es_archiver/lib/indices/__tests__/delete_index_stream.js
rename to src/es_archiver/lib/indices/__tests__/delete_index_stream.ts
index 955d1fff8779e..1c989ba158a29 100644
--- a/src/es_archiver/lib/indices/__tests__/delete_index_stream.js
+++ b/src/es_archiver/lib/indices/__tests__/delete_index_stream.ts
@@ -23,7 +23,14 @@ import { createListStream, createPromiseFromStreams } from '../../../../legacy/u
 
 import { createDeleteIndexStream } from '../delete_index_stream';
 
-import { createStubStats, createStubClient, createStubIndexRecord } from './stubs';
+import {
+  createStubStats,
+  createStubClient,
+  createStubIndexRecord,
+  createStubLogger,
+} from './stubs';
+
+const log = createStubLogger();
 
 describe('esArchiver: createDeleteIndexStream()', () => {
   it('deletes the index without checking if it exists', async () => {
@@ -32,13 +39,13 @@ describe('esArchiver: createDeleteIndexStream()', () => {
 
     await createPromiseFromStreams([
       createListStream([createStubIndexRecord('index1')]),
-      createDeleteIndexStream(client, stats),
+      createDeleteIndexStream(client, stats, log, []),
     ]);
 
-    sinon.assert.notCalled(stats.deletedIndex);
-    sinon.assert.notCalled(client.indices.create);
-    sinon.assert.calledOnce(client.indices.delete);
-    sinon.assert.notCalled(client.indices.exists);
+    sinon.assert.notCalled(stats.deletedIndex as sinon.SinonSpy);
+    sinon.assert.notCalled(client.indices.create as sinon.SinonSpy);
+    sinon.assert.calledOnce(client.indices.delete as sinon.SinonSpy);
+    sinon.assert.notCalled(client.indices.exists as sinon.SinonSpy);
   });
 
   it('reports the delete when the index existed', async () => {
@@ -47,12 +54,12 @@ describe('esArchiver: createDeleteIndexStream()', () => {
 
     await createPromiseFromStreams([
       createListStream([createStubIndexRecord('index1')]),
-      createDeleteIndexStream(client, stats),
+      createDeleteIndexStream(client, stats, log, []),
     ]);
 
-    sinon.assert.calledOnce(stats.deletedIndex);
-    sinon.assert.notCalled(client.indices.create);
-    sinon.assert.calledOnce(client.indices.delete);
-    sinon.assert.notCalled(client.indices.exists);
+    sinon.assert.calledOnce(stats.deletedIndex as sinon.SinonSpy);
+    sinon.assert.notCalled(client.indices.create as sinon.SinonSpy);
+    sinon.assert.calledOnce(client.indices.delete as sinon.SinonSpy);
+    sinon.assert.notCalled(client.indices.exists as sinon.SinonSpy);
   });
 });
diff --git a/src/es_archiver/lib/indices/__tests__/generate_index_records_stream.js b/src/es_archiver/lib/indices/__tests__/generate_index_records_stream.ts
similarity index 89%
rename from src/es_archiver/lib/indices/__tests__/generate_index_records_stream.js
rename to src/es_archiver/lib/indices/__tests__/generate_index_records_stream.ts
index 3523e9e82b153..7a3712ca1a336 100644
--- a/src/es_archiver/lib/indices/__tests__/generate_index_records_stream.js
+++ b/src/es_archiver/lib/indices/__tests__/generate_index_records_stream.ts
@@ -45,10 +45,10 @@ describe('esArchiver: createGenerateIndexRecordsStream()', () => {
       archivedIndex: 4,
     });
 
-    sinon.assert.callCount(client.indices.get, 4);
-    sinon.assert.notCalled(client.indices.create);
-    sinon.assert.notCalled(client.indices.delete);
-    sinon.assert.notCalled(client.indices.exists);
+    sinon.assert.callCount(client.indices.get as sinon.SinonSpy, 4);
+    sinon.assert.notCalled(client.indices.create as sinon.SinonSpy);
+    sinon.assert.notCalled(client.indices.delete as sinon.SinonSpy);
+    sinon.assert.notCalled(client.indices.exists as sinon.SinonSpy);
   });
 
   it('filters index metadata from settings', async () => {
@@ -60,9 +60,9 @@ describe('esArchiver: createGenerateIndexRecordsStream()', () => {
       createGenerateIndexRecordsStream(client, stats),
     ]);
 
-    const params = client.indices.get.args[0][0];
+    const params = (client.indices.get as sinon.SinonSpy).args[0][0];
     expect(params).to.have.property('filterPath');
-    const filters = params.filterPath;
+    const filters: string[] = params.filterPath;
     expect(filters.some(path => path.includes('index.creation_date'))).to.be(true);
     expect(filters.some(path => path.includes('index.uuid'))).to.be(true);
     expect(filters.some(path => path.includes('index.version'))).to.be(true);
@@ -73,7 +73,7 @@ describe('esArchiver: createGenerateIndexRecordsStream()', () => {
     const stats = createStubStats();
     const client = createStubClient(['index1', 'index2', 'index3']);
 
-    const indexRecords = await createPromiseFromStreams([
+    const indexRecords = await createPromiseFromStreams<any[]>([
       createListStream(['index1', 'index2', 'index3']),
       createGenerateIndexRecordsStream(client, stats),
       createConcatStream([]),
diff --git a/src/es_archiver/lib/indices/__tests__/stubs.js b/src/es_archiver/lib/indices/__tests__/stubs.js
deleted file mode 100644
index 00649a06f9efe..0000000000000
--- a/src/es_archiver/lib/indices/__tests__/stubs.js
+++ /dev/null
@@ -1,128 +0,0 @@
-/*
- * Licensed to Elasticsearch B.V. under one or more contributor
- * license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright
- * ownership. Elasticsearch B.V. licenses this file to you under
- * the Apache License, Version 2.0 (the "License"); you may
- * not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-
-import sinon from 'sinon';
-
-export const createStubStats = () => ({
-  createdIndex: sinon.stub(),
-  createdAliases: sinon.stub(),
-  deletedIndex: sinon.stub(),
-  skippedIndex: sinon.stub(),
-  archivedIndex: sinon.stub(),
-  getTestSummary() {
-    const summary = {};
-    Object.keys(this).forEach(key => {
-      if (this[key].callCount) {
-        summary[key] = this[key].callCount;
-      }
-    });
-    return summary;
-  },
-});
-
-export const createStubIndexRecord = (index, aliases = {}) => ({
-  type: 'index',
-  value: { index, aliases },
-});
-
-export const createStubDocRecord = (index, id) => ({
-  type: 'doc',
-  value: { index, id },
-});
-
-const createEsClientError = errorType => {
-  const err = new Error(`ES Client Error Stub "${errorType}"`);
-  err.body = {
-    error: {
-      type: errorType,
-    },
-  };
-  return err;
-};
-
-const indexAlias = (aliases, index) => Object.keys(aliases).find(k => aliases[k] === index);
-
-export const createStubClient = (existingIndices = [], aliases = {}) => ({
-  indices: {
-    get: sinon.spy(async ({ index }) => {
-      if (!existingIndices.includes(index)) {
-        throw createEsClientError('index_not_found_exception');
-      }
-
-      return {
-        [index]: {
-          mappings: {},
-          settings: {},
-        },
-      };
-    }),
-    existsAlias: sinon.spy(({ name }) => {
-      return Promise.resolve(aliases.hasOwnProperty(name));
-    }),
-    getAlias: sinon.spy(async ({ index, name }) => {
-      if (index && existingIndices.indexOf(index) >= 0) {
-        const result = indexAlias(aliases, index);
-        return { [index]: { aliases: result ? { [result]: {} } : {} } };
-      }
-
-      if (name && aliases[name]) {
-        return { [aliases[name]]: { aliases: { [name]: {} } } };
-      }
-
-      return { status: 404 };
-    }),
-    updateAliases: sinon.spy(async ({ body }) => {
-      body.actions.forEach(({ add: { index, alias } }) => {
-        if (!existingIndices.includes(index)) {
-          throw createEsClientError('index_not_found_exception');
-        }
-        existingIndices.push({ index, alias });
-      });
-
-      return { ok: true };
-    }),
-    create: sinon.spy(async ({ index }) => {
-      if (existingIndices.includes(index) || aliases.hasOwnProperty(index)) {
-        throw createEsClientError('resource_already_exists_exception');
-      } else {
-        existingIndices.push(index);
-        return { ok: true };
-      }
-    }),
-    delete: sinon.spy(async ({ index }) => {
-      const indices = Array.isArray(index) ? index : [index];
-      if (indices.every(ix => existingIndices.includes(ix))) {
-        // Delete aliases associated with our indices
-        indices.forEach(ix => {
-          const alias = Object.keys(aliases).find(k => aliases[k] === ix);
-          if (alias) {
-            delete aliases[alias];
-          }
-        });
-        indices.forEach(ix => existingIndices.splice(existingIndices.indexOf(ix), 1));
-        return { ok: true };
-      } else {
-        throw createEsClientError('index_not_found_exception');
-      }
-    }),
-    exists: sinon.spy(async () => {
-      throw new Error('Do not use indices.exists(). React to errors instead.');
-    }),
-  },
-});
diff --git a/src/es_archiver/lib/indices/__tests__/stubs.ts b/src/es_archiver/lib/indices/__tests__/stubs.ts
new file mode 100644
index 0000000000000..3f4682299c38d
--- /dev/null
+++ b/src/es_archiver/lib/indices/__tests__/stubs.ts
@@ -0,0 +1,154 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import { Client } from 'elasticsearch';
+import sinon from 'sinon';
+import { ToolingLog } from '@kbn/dev-utils';
+import { Stats } from '../../stats';
+
+type StubStats = Stats & {
+  getTestSummary: () => Record<string, number>;
+};
+
+export const createStubStats = (): StubStats =>
+  ({
+    createdIndex: sinon.stub(),
+    createdAliases: sinon.stub(),
+    deletedIndex: sinon.stub(),
+    skippedIndex: sinon.stub(),
+    archivedIndex: sinon.stub(),
+    getTestSummary() {
+      const summary: Record<string, number> = {};
+      Object.keys(this).forEach(key => {
+        if (this[key].callCount) {
+          summary[key] = this[key].callCount;
+        }
+      });
+      return summary;
+    },
+  } as any);
+
+export const createStubLogger = (): ToolingLog =>
+  ({
+    debug: sinon.stub(),
+    info: sinon.stub(),
+    success: sinon.stub(),
+    warning: sinon.stub(),
+    error: sinon.stub(),
+  } as any);
+
+export const createStubIndexRecord = (index: string, aliases = {}) => ({
+  type: 'index',
+  value: { index, aliases },
+});
+
+export const createStubDocRecord = (index: string, id: number) => ({
+  type: 'doc',
+  value: { index, id },
+});
+
+const createEsClientError = (errorType: string) => {
+  const err = new Error(`ES Client Error Stub "${errorType}"`);
+  (err as any).body = {
+    error: {
+      type: errorType,
+    },
+  };
+  return err;
+};
+
+const indexAlias = (aliases: Record<string, any>, index: string) =>
+  Object.keys(aliases).find(k => aliases[k] === index);
+
+type StubClient = Client;
+
+export const createStubClient = (
+  existingIndices: string[] = [],
+  aliases: Record<string, any> = {}
+): StubClient =>
+  ({
+    indices: {
+      get: sinon.spy(async ({ index }) => {
+        if (!existingIndices.includes(index)) {
+          throw createEsClientError('index_not_found_exception');
+        }
+
+        return {
+          [index]: {
+            mappings: {},
+            settings: {},
+          },
+        };
+      }),
+      existsAlias: sinon.spy(({ name }) => {
+        return Promise.resolve(aliases.hasOwnProperty(name));
+      }),
+      getAlias: sinon.spy(async ({ index, name }) => {
+        if (index && existingIndices.indexOf(index) >= 0) {
+          const result = indexAlias(aliases, index);
+          return { [index]: { aliases: result ? { [result]: {} } : {} } };
+        }
+
+        if (name && aliases[name]) {
+          return { [aliases[name]]: { aliases: { [name]: {} } } };
+        }
+
+        return { status: 404 };
+      }),
+      updateAliases: sinon.spy(async ({ body }) => {
+        body.actions.forEach(
+          ({ add: { index, alias } }: { add: { index: string; alias: string } }) => {
+            if (!existingIndices.includes(index)) {
+              throw createEsClientError('index_not_found_exception');
+            }
+            existingIndices.push({ index, alias } as any);
+          }
+        );
+
+        return { ok: true };
+      }),
+      create: sinon.spy(async ({ index }) => {
+        if (existingIndices.includes(index) || aliases.hasOwnProperty(index)) {
+          throw createEsClientError('resource_already_exists_exception');
+        } else {
+          existingIndices.push(index);
+          return { ok: true };
+        }
+      }),
+      delete: sinon.spy(async ({ index }) => {
+        const indices = Array.isArray(index) ? index : [index];
+        if (indices.every(ix => existingIndices.includes(ix))) {
+          // Delete aliases associated with our indices
+          indices.forEach(ix => {
+            const alias = Object.keys(aliases).find(k => aliases[k] === ix);
+            if (alias) {
+              delete aliases[alias];
+            }
+          });
+          indices.forEach(ix => existingIndices.splice(existingIndices.indexOf(ix), 1));
+          return { ok: true };
+        } else {
+          throw createEsClientError('index_not_found_exception');
+        }
+      }),
+      exists: sinon.spy(async () => {
+        throw new Error('Do not use indices.exists(). React to errors instead.');
+      }),
+    },
+  } as any);
diff --git a/src/es_archiver/lib/indices/create_index_stream.js b/src/es_archiver/lib/indices/create_index_stream.ts
similarity index 81%
rename from src/es_archiver/lib/indices/create_index_stream.js
rename to src/es_archiver/lib/indices/create_index_stream.ts
index 8fe4bc568cd23..df9d3bb623ad6 100644
--- a/src/es_archiver/lib/indices/create_index_stream.js
+++ b/src/es_archiver/lib/indices/create_index_stream.ts
@@ -17,13 +17,36 @@
  * under the License.
  */
 
-import { Transform } from 'stream';
-
+import { Transform, Readable } from 'stream';
 import { get, once } from 'lodash';
+import { Client } from 'elasticsearch';
+import { ToolingLog } from '@kbn/dev-utils';
+
+import { Stats } from '../stats';
 import { deleteKibanaIndices } from './kibana_index';
 import { deleteIndex } from './delete_index';
 
-export function createCreateIndexStream({ client, stats, skipExisting, log }) {
+interface DocRecord {
+  value: {
+    index: string;
+    type: string;
+    settings: Record<string, any>;
+    mappings: Record<string, any>;
+    aliases: Record<string, any>;
+  };
+}
+
+export function createCreateIndexStream({
+  client,
+  stats,
+  skipExisting = false,
+  log,
+}: {
+  client: Client;
+  stats: Stats;
+  skipExisting?: boolean;
+  log: ToolingLog;
+}) {
   const skipDocsFromIndices = new Set();
 
   // If we're trying to import Kibana index docs, we need to ensure that
@@ -31,7 +54,7 @@ export function createCreateIndexStream({ client, stats, skipExisting, log }) {
   // migrations. This only needs to be done once per archive load operation.
   const deleteKibanaIndicesOnce = once(deleteKibanaIndices);
 
-  async function handleDoc(stream, record) {
+  async function handleDoc(stream: Readable, record: DocRecord) {
     if (skipDocsFromIndices.has(record.value.index)) {
       return;
     }
@@ -39,7 +62,7 @@ export function createCreateIndexStream({ client, stats, skipExisting, log }) {
     stream.push(record);
   }
 
-  async function handleIndex(record) {
+  async function handleIndex(record: DocRecord) {
     const { index, settings, mappings, aliases } = record.value;
     const isKibana = index.startsWith('.kibana');
 
@@ -102,7 +125,7 @@ export function createCreateIndexStream({ client, stats, skipExisting, log }) {
             break;
         }
 
-        callback(null);
+        callback();
       } catch (err) {
         callback(err);
       }
diff --git a/src/es_archiver/lib/indices/delete_index.js b/src/es_archiver/lib/indices/delete_index.ts
similarity index 76%
rename from src/es_archiver/lib/indices/delete_index.js
rename to src/es_archiver/lib/indices/delete_index.ts
index 6f60d9533a36b..e3fca587fbc3d 100644
--- a/src/es_archiver/lib/indices/delete_index.js
+++ b/src/es_archiver/lib/indices/delete_index.ts
@@ -18,22 +18,34 @@
  */
 
 import { get } from 'lodash';
+import { Client } from 'elasticsearch';
+import { ToolingLog } from '@kbn/dev-utils';
+import { Stats } from '../stats';
 
 // see https://github.com/elastic/elasticsearch/blob/99f88f15c5febbca2d13b5b5fda27b844153bf1a/server/src/main/java/org/elasticsearch/cluster/SnapshotsInProgress.java#L313-L319
 const PENDING_SNAPSHOT_STATUSES = ['INIT', 'STARTED', 'WAITING'];
 
-export async function deleteIndex(options) {
+export async function deleteIndex(options: {
+  client: Client;
+  stats: Stats;
+  index: string;
+  log: ToolingLog;
+  retryIfSnapshottingCount?: number;
+}): Promise<void> {
   const { client, stats, index, log, retryIfSnapshottingCount = 10 } = options;
 
   const getIndicesToDelete = async () => {
     const aliasInfo = await client.indices.getAlias({ name: index, ignore: [404] });
-    return aliasInfo.status === 404 ? index : Object.keys(aliasInfo);
+    return aliasInfo.status === 404 ? [index] : Object.keys(aliasInfo);
   };
 
   try {
     const indicesToDelete = await getIndicesToDelete();
     await client.indices.delete({ index: indicesToDelete });
-    stats.deletedIndex(indicesToDelete);
+    for (let i = 0; i < indicesToDelete.length; i++) {
+      const indexToDelete = indicesToDelete[i];
+      stats.deletedIndex(indexToDelete);
+    }
   } catch (error) {
     if (retryIfSnapshottingCount > 0 && isDeleteWhileSnapshotInProgressError(error)) {
       stats.waitingForInProgressSnapshot(index);
@@ -56,7 +68,7 @@ export async function deleteIndex(options) {
  * @param  {Error} error
  * @return {Boolean}
  */
-export function isDeleteWhileSnapshotInProgressError(error) {
+export function isDeleteWhileSnapshotInProgressError(error: object) {
   return get(error, 'body.error.reason', '').startsWith(
     'Cannot delete indices that are being snapshotted'
   );
@@ -65,13 +77,9 @@ export function isDeleteWhileSnapshotInProgressError(error) {
 /**
  * Wait for the any snapshot in any repository that is
  * snapshotting this index to complete.
- *
- * @param  {EsClient} client
- * @param  {string} index the name of the index to look for
- * @return {Promise<undefined>}
  */
-export async function waitForSnapshotCompletion(client, index, log) {
-  const isSnapshotPending = async (repository, snapshot) => {
+export async function waitForSnapshotCompletion(client: Client, index: string, log: ToolingLog) {
+  const isSnapshotPending = async (repository: string, snapshot: string) => {
     const {
       snapshots: [status],
     } = await client.snapshot.status({
@@ -83,7 +91,7 @@ export async function waitForSnapshotCompletion(client, index, log) {
     return PENDING_SNAPSHOT_STATUSES.includes(status.state);
   };
 
-  const getInProgressSnapshots = async repository => {
+  const getInProgressSnapshots = async (repository: string) => {
     const { snapshots: inProgressSnapshots } = await client.snapshot.get({
       repository,
       snapshot: '_current',
@@ -91,9 +99,9 @@ export async function waitForSnapshotCompletion(client, index, log) {
     return inProgressSnapshots;
   };
 
-  for (const repository of Object.keys(await client.snapshot.getRepository())) {
+  for (const repository of Object.keys(await client.snapshot.getRepository({} as any))) {
     const allInProgress = await getInProgressSnapshots(repository);
-    const found = allInProgress.find(s => s.indices.includes(index));
+    const found = allInProgress.find((s: any) => s.indices.includes(index));
 
     if (!found) {
       continue;
diff --git a/src/es_archiver/lib/indices/delete_index_stream.js b/src/es_archiver/lib/indices/delete_index_stream.ts
similarity index 86%
rename from src/es_archiver/lib/indices/delete_index_stream.js
rename to src/es_archiver/lib/indices/delete_index_stream.ts
index 31a49ed30a124..b4e1e530e1f84 100644
--- a/src/es_archiver/lib/indices/delete_index_stream.js
+++ b/src/es_archiver/lib/indices/delete_index_stream.ts
@@ -18,11 +18,19 @@
  */
 
 import { Transform } from 'stream';
+import { Client } from 'elasticsearch';
+import { ToolingLog } from '@kbn/dev-utils';
 
+import { Stats } from '../stats';
 import { deleteIndex } from './delete_index';
 import { cleanKibanaIndices } from './kibana_index';
 
-export function createDeleteIndexStream(client, stats, log, kibanaPluginIds) {
+export function createDeleteIndexStream(
+  client: Client,
+  stats: Stats,
+  log: ToolingLog,
+  kibanaPluginIds: string[]
+) {
   return new Transform({
     readableObjectMode: true,
     writableObjectMode: true,
diff --git a/src/es_archiver/lib/indices/generate_index_records_stream.js b/src/es_archiver/lib/indices/generate_index_records_stream.ts
similarity index 89%
rename from src/es_archiver/lib/indices/generate_index_records_stream.js
rename to src/es_archiver/lib/indices/generate_index_records_stream.ts
index 1d1a44aa634c2..b4b98f8ae262c 100644
--- a/src/es_archiver/lib/indices/generate_index_records_stream.js
+++ b/src/es_archiver/lib/indices/generate_index_records_stream.ts
@@ -18,14 +18,16 @@
  */
 
 import { Transform } from 'stream';
+import { Client } from 'elasticsearch';
+import { Stats } from '../stats';
 
-export function createGenerateIndexRecordsStream(client, stats) {
+export function createGenerateIndexRecordsStream(client: Client, stats: Stats) {
   return new Transform({
     writableObjectMode: true,
     readableObjectMode: true,
     async transform(indexOrAlias, enc, callback) {
       try {
-        const resp = await client.indices.get({
+        const resp = (await client.indices.get({
           index: indexOrAlias,
           filterPath: [
             '*.settings',
@@ -36,7 +38,7 @@ export function createGenerateIndexRecordsStream(client, stats) {
             '-*.settings.index.version',
             '-*.settings.index.provided_name',
           ],
-        });
+        })) as Record<string, any>;
 
         for (const [index, { settings, mappings }] of Object.entries(resp)) {
           const {
diff --git a/src/es_archiver/lib/indices/index.js b/src/es_archiver/lib/indices/index.ts
similarity index 100%
rename from src/es_archiver/lib/indices/index.js
rename to src/es_archiver/lib/indices/index.ts
diff --git a/src/es_archiver/lib/indices/kibana_index.js b/src/es_archiver/lib/indices/kibana_index.ts
similarity index 70%
rename from src/es_archiver/lib/indices/kibana_index.js
rename to src/es_archiver/lib/indices/kibana_index.ts
index 744132bdcef69..de67ba7c4e31e 100644
--- a/src/es_archiver/lib/indices/kibana_index.js
+++ b/src/es_archiver/lib/indices/kibana_index.ts
@@ -17,29 +17,34 @@
  * under the License.
  */
 
-import _ from 'lodash';
+import { get } from 'lodash';
 import fs from 'fs';
-import path from 'path';
+import Path from 'path';
 import { promisify } from 'util';
 import { toArray } from 'rxjs/operators';
+import { Client, CreateDocumentParams } from 'elasticsearch';
+import { ToolingLog } from '@kbn/dev-utils';
 
+import { Stats } from '../stats';
 import { deleteIndex } from './delete_index';
-import { collectUiExports } from '../../../legacy/ui/ui_exports';
 import { KibanaMigrator } from '../../../core/server/saved_objects/migrations';
 import { SavedObjectsSchema } from '../../../core/server/saved_objects';
+// @ts-ignore
+import { collectUiExports } from '../../../legacy/ui/ui_exports';
+// @ts-ignore
 import { findPluginSpecs } from '../../../legacy/plugin_discovery';
 
 /**
  * Load the uiExports for a Kibana instance, only load uiExports from xpack if
  * it is enabled in the Kibana server.
  */
-const getUiExports = async kibanaPluginIds => {
+const getUiExports = async (kibanaPluginIds: string[]) => {
   const xpackEnabled = kibanaPluginIds.includes('xpack_main');
 
   const { spec$ } = await findPluginSpecs({
     plugins: {
-      scanDirs: [path.resolve(__dirname, '../../../legacy/core_plugins')],
-      paths: xpackEnabled ? [path.resolve(__dirname, '../../../../x-pack')] : [],
+      scanDirs: [Path.resolve(__dirname, '../../../legacy/core_plugins')],
+      paths: xpackEnabled ? [Path.resolve(__dirname, '../../../../x-pack')] : [],
     },
   });
 
@@ -50,7 +55,15 @@ const getUiExports = async kibanaPluginIds => {
 /**
  * Deletes all indices that start with `.kibana`
  */
-export async function deleteKibanaIndices({ client, stats, log }) {
+export async function deleteKibanaIndices({
+  client,
+  stats,
+  log,
+}: {
+  client: Client;
+  stats: Stats;
+  log: ToolingLog;
+}) {
   const indexNames = await fetchKibanaIndices(client);
   if (!indexNames.length) {
     return;
@@ -76,37 +89,52 @@ export async function deleteKibanaIndices({ client, stats, log }) {
  * builds up an object that implements just enough of the kbnMigrations interface
  * as is required by migrations.
  */
-export async function migrateKibanaIndex({ client, log, kibanaPluginIds }) {
+export async function migrateKibanaIndex({
+  client,
+  log,
+  kibanaPluginIds,
+}: {
+  client: Client;
+  log: ToolingLog;
+  kibanaPluginIds: string[];
+}) {
   const uiExports = await getUiExports(kibanaPluginIds);
   const kibanaVersion = await loadKibanaVersion();
 
-  const config = {
+  const config: Record<string, string> = {
     'xpack.task_manager.index': '.kibana_task_manager',
   };
 
+  const logger = {
+    trace: log.verbose.bind(log),
+    debug: log.debug.bind(log),
+    info: log.info.bind(log),
+    warn: log.warning.bind(log),
+    error: log.error.bind(log),
+    fatal: log.error.bind(log),
+    log: (entry: any) => log.info(entry.message),
+    get: () => logger,
+  };
+
   const migratorOptions = {
-    config: { get: path => config[path] },
+    config: { get: (path: string) => config[path] } as any,
     savedObjectsConfig: {
       scrollDuration: '5m',
       batchSize: 100,
       pollInterval: 100,
+      skip: false,
     },
     kibanaConfig: {
       index: '.kibana',
-    },
-    logger: {
-      trace: log.verbose.bind(log),
-      debug: log.debug.bind(log),
-      info: log.info.bind(log),
-      warn: log.warning.bind(log),
-      error: log.error.bind(log),
-    },
-    version: kibanaVersion,
+    } as any,
+    logger,
+    kibanaVersion,
     savedObjectSchemas: new SavedObjectsSchema(uiExports.savedObjectSchemas),
     savedObjectMappings: uiExports.savedObjectMappings,
     savedObjectMigrations: uiExports.savedObjectMigrations,
     savedObjectValidations: uiExports.savedObjectValidations,
-    callCluster: (path, ...args) => _.get(client, path).call(client, ...args),
+    callCluster: (path: string, ...args: any[]) =>
+      (get(client, path) as Function).call(client, ...args),
   };
 
   return await new KibanaMigrator(migratorOptions).runMigrations();
@@ -114,8 +142,8 @@ export async function migrateKibanaIndex({ client, log, kibanaPluginIds }) {
 
 async function loadKibanaVersion() {
   const readFile = promisify(fs.readFile);
-  const packageJson = await readFile(path.join(__dirname, '../../../../package.json'));
-  return JSON.parse(packageJson).version;
+  const packageJson = await readFile(Path.join(__dirname, '../../../../package.json'));
+  return JSON.parse(packageJson.toString('utf-8')).version;
 }
 
 /**
@@ -123,16 +151,24 @@ async function loadKibanaVersion() {
  * .kibana, .kibana_1, .kibana_323, etc. This finds all indices starting
  * with .kibana, then filters out any that aren't actually Kibana's core
  * index (e.g. we don't want to remove .kibana_task_manager or the like).
- *
- * @param {string} index
  */
-async function fetchKibanaIndices(client) {
+async function fetchKibanaIndices(client: Client) {
   const kibanaIndices = await client.cat.indices({ index: '.kibana*', format: 'json' });
-  const isKibanaIndex = index => /^\.kibana(:?_\d*)?$/.test(index);
-  return kibanaIndices.map(x => x.index).filter(isKibanaIndex);
+  const isKibanaIndex = (index: string) => /^\.kibana(:?_\d*)?$/.test(index);
+  return kibanaIndices.map((x: { index: string }) => x.index).filter(isKibanaIndex);
 }
 
-export async function cleanKibanaIndices({ client, stats, log, kibanaPluginIds }) {
+export async function cleanKibanaIndices({
+  client,
+  stats,
+  log,
+  kibanaPluginIds,
+}: {
+  client: Client;
+  stats: Stats;
+  log: ToolingLog;
+  kibanaPluginIds: string[];
+}) {
   if (!kibanaPluginIds.includes('spaces')) {
     return await deleteKibanaIndices({
       client,
@@ -178,7 +214,7 @@ export async function cleanKibanaIndices({ client, stats, log, kibanaPluginIds }
   stats.deletedIndex('.kibana');
 }
 
-export async function createDefaultSpace({ index, client }) {
+export async function createDefaultSpace({ index, client }: { index: string; client: Client }) {
   await client.create({
     index,
     id: 'space:default',
@@ -193,5 +229,5 @@ export async function createDefaultSpace({ index, client }) {
         _reserved: true,
       },
     },
-  });
+  } as CreateDocumentParams);
 }
diff --git a/src/es_archiver/lib/records/__tests__/filter_records_stream.js b/src/es_archiver/lib/records/__tests__/filter_records_stream.ts
similarity index 97%
rename from src/es_archiver/lib/records/__tests__/filter_records_stream.js
rename to src/es_archiver/lib/records/__tests__/filter_records_stream.ts
index fd35575ca59ba..d5830478decba 100644
--- a/src/es_archiver/lib/records/__tests__/filter_records_stream.js
+++ b/src/es_archiver/lib/records/__tests__/filter_records_stream.ts
@@ -51,7 +51,7 @@ describe('esArchiver: createFilterRecordsStream()', () => {
 
   it('produces record values that have a matching type', async () => {
     const type1 = chance.word({ length: 5 });
-    const output = await createPromiseFromStreams([
+    const output = await createPromiseFromStreams<any[]>([
       createListStream([
         { type: type1, value: {} },
         { type: type1, value: {} },
diff --git a/src/es_archiver/lib/records/filter_records_stream.js b/src/es_archiver/lib/records/filter_records_stream.ts
similarity index 91%
rename from src/es_archiver/lib/records/filter_records_stream.js
rename to src/es_archiver/lib/records/filter_records_stream.ts
index 5a835ffe8e84d..191cbd3b921e3 100644
--- a/src/es_archiver/lib/records/filter_records_stream.js
+++ b/src/es_archiver/lib/records/filter_records_stream.ts
@@ -19,14 +19,14 @@
 
 import { Transform } from 'stream';
 
-export function createFilterRecordsStream(type) {
+export function createFilterRecordsStream(type: string) {
   return new Transform({
     writableObjectMode: true,
     readableObjectMode: true,
 
     transform(record, enc, callback) {
       if (record && record.type === type) {
-        callback(null, record);
+        callback(undefined, record);
       } else {
         callback();
       }
diff --git a/src/es_archiver/lib/records/index.js b/src/es_archiver/lib/records/index.ts
similarity index 100%
rename from src/es_archiver/lib/records/index.js
rename to src/es_archiver/lib/records/index.ts
diff --git a/src/es_archiver/lib/stats.ts b/src/es_archiver/lib/stats.ts
index 5f73304abf9a8..c69b764fc7290 100644
--- a/src/es_archiver/lib/stats.ts
+++ b/src/es_archiver/lib/stats.ts
@@ -37,6 +37,8 @@ export interface IndexStats {
   };
 }
 
+export type Stats = ReturnType<typeof createStats>;
+
 export function createStats(name: string, log: ToolingLog) {
   const info = (msg: string, ...args: any[]) => log.info(`[${name}] ${msg}`, ...args);
   const debug = (msg: string, ...args: any[]) => log.debug(`[${name}] ${msg}`, ...args);
diff --git a/src/legacy/utils/index.d.ts b/src/legacy/utils/index.d.ts
index a57caad1d34bf..c294c79542bbe 100644
--- a/src/legacy/utils/index.d.ts
+++ b/src/legacy/utils/index.d.ts
@@ -18,3 +18,16 @@
  */
 
 export function unset(object: object, rawPath: string): void;
+
+export {
+  concatStreamProviders,
+  createConcatStream,
+  createFilterStream,
+  createIntersperseStream,
+  createListStream,
+  createMapStream,
+  createPromiseFromStreams,
+  createReduceStream,
+  createReplaceStream,
+  createSplitStream,
+} from './streams';
diff --git a/src/legacy/utils/streams/index.d.ts b/src/legacy/utils/streams/index.d.ts
index b8d4c67050b2d..5ef39b292c685 100644
--- a/src/legacy/utils/streams/index.d.ts
+++ b/src/legacy/utils/streams/index.d.ts
@@ -20,17 +20,17 @@
 import { Readable, Transform, Writable, TransformOptions } from 'stream';
 
 export function concatStreamProviders(
-  sourceProviders: Readable[],
+  sourceProviders: Array<() => Readable>,
   options: TransformOptions
 ): Transform;
 export function createIntersperseStream(intersperseChunk: string | Buffer): Transform;
 export function createSplitStream<T>(splitChunk: T): Transform;
-export function createListStream(items: any[]): Readable;
+export function createListStream(items: any | any[]): Readable;
 export function createReduceStream<T>(reducer: (value: any, chunk: T, enc: string) => T): Transform;
 export function createPromiseFromStreams<T>([first, ...rest]: [Readable, ...Writable[]]): Promise<
   T
 >;
-export function createConcatStream(initial: any): Transform;
+export function createConcatStream(initial?: any): Transform;
 export function createMapStream<T>(fn: (value: T, i: number) => void): Transform;
 export function createReplaceStream(toReplace: string, replacement: string | Buffer): Transform;
 export function createFilterStream<T>(fn: (obj: T) => boolean): Transform;