use ntp time to avoid issues with local clock drift and watchStack

It would previously skip events and hang waiting for a terminal status
if the local clock had drifted ahead of AWS.

This is probably just a stop-gap and I will refactor this further to
use previous stack events or the CreationTimestamp as the startTime
marker rather than calling out to ntp.

package.json

@@ -27,6 +27,7 @@
     "inquirer": "^3.2.1",
     "js-yaml": "^3.8.3",
     "lodash": "^4.17.4",
+    "ntp-client": "^0.5.3",
     "openpgp": "^2.5.8",
     "ora": "^1.3.0",
     "project-name-generator": "^2.1.3",

src/getReliableTime.ts

@@ -0,0 +1,22 @@
+import { logger } from './logger';
+import * as Promise from 'bluebird';
+
+let ntpClient: any;
+ntpClient = require('ntp-client');
+ntpClient.ntpReplyTimeout = 2000;
+type _getNetworkTime = (server: string, port: number, callback: (err: any, ts:Date)=> void) => void;
+let _getNetworkTime: _getNetworkTime;
+_getNetworkTime = ntpClient.getNetworkTime;
+const getNetworkTime = Promise.promisify(_getNetworkTime);
+
+const getReliableTime = (): Promise<Date> =>
+  getNetworkTime("pool.ntp.org", 123)
+  .catch((e) => {
+    logger.info('error in getNetworkTime. Retrying', e=e)
+    return getNetworkTime("pool.ntp.org", 123)
+  }).catch((e) => {
+    logger.info('error in getNetworkTime. Falling back to new Date()', e=e)
+    return new Date();
+  });
+
+export default getReliableTime;

src/index.ts

@@ -919,6 +919,8 @@ async function watchStack(StackName: string, startTime: Date, pollInterval=2) {
   const spinner = ora({spinner: 'dots12',
                        text: '',
                        enabled: _.isNumber(tty.columns)});
+  // TODO consider doing: const spinnerStart = new Date()
+  // to ensure calcElapsedSeconds is accurate in the face of innacurate local clocks
   const calcElapsedSeconds = () => Math.ceil((+(new Date()) - +(startTime))/1000);
   let DONE = false;
   while (! DONE) {
@@ -928,9 +930,11 @@ async function watchStack(StackName: string, startTime: Date, pollInterval=2) {
     const statusPadding = _.max(_.map(evs, (ev)=> (ev.ResourceStatus as string).length))
     for (let ev of evs) {
       if (ev.Timestamp < startTime) {
+        logger.debug('filtering event from past', ev=ev, startTime=startTime);
         seen[ev.EventId] = true
       }
       if (!seen[ev.EventId]){
+        logger.debug('displaying new event', ev=ev, startTime=startTime);
         displayStackEvent(ev, statusPadding);
       }
       seen[ev.EventId] = true
@@ -1109,7 +1113,9 @@ async function summarizeStackProperties(StackName: string, region: string, showT
   //console.log('Stack OnFailure Mode:', cli.blackBright(OnFailure));
   if (showTimes) {
     printEntry('Creation Time:', cli.blackBright(renderTimestamp(stack.CreationTime)));
-    printEntry('Last Update Time:', cli.blackBright(renderTimestamp(stack.LastUpdatedTime || stack.CreationTime)));
+    if (stack.LastUpdatedTime) {
+      printEntry('Last Update Time:', cli.blackBright(renderTimestamp(stack.LastUpdatedTime)));
+    }
   }
   printEntry('Timeout In Minutes:', cli.blackBright(stack.TimeoutInMinutes || 'None'));
   printEntry('NotificationARNs:', cli.blackBright(_.isEmpty(stack.NotificationARNs) ? 'None' : stack.NotificationARNs));
@@ -1201,6 +1207,17 @@ async function listStacks() {
 //////////////////////////////////////////////////////////////////////
 import {Arguments} from 'yargs';
 
+import getReliableTime from './getReliableTime';
+
+async function getReliableStartTime(): Promise<Date>{
+  const startTime = await getReliableTime();
+  startTime.setTime(startTime.getTime() - 500); // to be safe
+  // TODO warn about inaccurate local clocks as that will affect the calculation of elapsed time.
+  return startTime;
+}
+
+
+
 export async function renderMain(argv: Arguments): Promise<number> {
   await configureAWS(argv.profile, argv.region)
   const rootDocLocation = pathmod.resolve(argv.template);
@@ -1378,7 +1395,7 @@ abstract class AbstractCloudFormationStackCommand {
   async run(): Promise<number> {
     await this._setup()
     await this._showCommandSummary()
-    this._startTime = new Date();
+    this._startTime = await getReliableStartTime();
     return this._run()
   }
 
@@ -1657,9 +1674,9 @@ export async function deleteStackMain(argv: Arguments): Promise<number> {
   if (confirmed) {
     const cfn = new aws.CloudFormation();
      // --retain-resources, --client-request-token
+    const startTime = await getReliableStartTime();
     const deleteStackOutput = await cfn.deleteStack(
       {StackName, RoleARN: argv.roleArn}).promise();
-    const startTime = new Date();
     const StackId: string = stack.StackId as string;
     await watchStack(StackId as string, startTime);
     console.log();