From 0a199c2114f764448273d033952f76747a1d4510 Mon Sep 17 00:00:00 2001
From: Fred Bricon <fbricon@gmail.com>
Date: Tue, 16 Mar 2021 11:31:27 +0100
Subject: [PATCH] Only show replication factor input when relevant

When creating a new topic from the wizard

- read offsets.topic.replication.factor from broker config to determine max replication factor
- fallback to default.replication.factor
- fallback to the lowest value between 3 and the number of brokers (looking at you cloudkarafka)

If value <= 1, the replication factor input is not shown in the topic wizard

Fixes #64

Signed-off-by: Fred Bricon <fbricon@gmail.com>
---
 CHANGELOG.md          |  3 +++
 src/wizards/topics.ts | 53 ++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 53 insertions(+), 3 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index ddff6a5..991ef15 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,9 @@ All notable changes to Kafka extension will be documented in this file.
 ### Added
 - Extension API to contribute clusters. See [#123](https://github.com/jlandersen/vscode-kafka/issues/123).
 
+### Changed
+- Improved the "New topic" wizard: the replication factor is now read from the broker configuration. Input will be skipped if value can't be higher than 1. See [#64](https://github.com/jlandersen/vscode-kafka/issues/64).
+
 ## [0.11.0] - 2021-03-08
 ### Added
 - Newly created topic or cluster is automatically selected in the Kafka Explorer. See [#61](https://github.com/jlandersen/vscode-kafka/issues/61).
diff --git a/src/wizards/topics.ts b/src/wizards/topics.ts
index 575905b..2252374 100644
--- a/src/wizards/topics.ts
+++ b/src/wizards/topics.ts
@@ -7,13 +7,16 @@ import { MultiStepInput, showErrorMessage, State } from "./multiStepInput";
 import { validateTopicName, validatePartitions, validateReplicationFactor } from "./validators";
 
 const DEFAULT_PARTITIONS = 1;
-const DEFAULT_REPLICATION_FACTOR = 1;
+
+const REPLICATION_FACTOR_KEY = 'offsets.topic.replication.factor';
+const DEFAULT_REPLICATION_FACTOR_KEY = 'default.replication.factor';
 
 interface CreateTopicState extends State {
     clusterId: string;
     topicName: string;
     partitions: string;
     replicationFactor: string;
+    maxReplicas: number;
 }
 
 export async function addTopicWizard(clientAccessor: ClientAccessor, clusterSettings: ClusterSettings, explorer: KafkaExplorer, clusterId?: string): Promise<void> {
@@ -82,6 +85,12 @@ export async function addTopicWizard(clientAccessor: ClientAccessor, clusterSett
 
 async function collectInputs(state: Partial<CreateTopicState>, clusterSettings: ClusterSettings, clientAccessor: ClientAccessor) {
     if (state.clusterId) {
+        if (!state.maxReplicas) {
+            state.maxReplicas = await getMaxReplicas(clientAccessor, state.clusterId);
+            if (state.maxReplicas <= 1) {
+                state.totalSteps = state.totalSteps! -1;
+            }
+        }
         await MultiStepInput.run(input => inputTopicName(input, state, clientAccessor));
     } else {
         await MultiStepInput.run(input => inputSelectCluster(input, state, clusterSettings, clientAccessor));
@@ -89,6 +98,8 @@ async function collectInputs(state: Partial<CreateTopicState>, clusterSettings:
 }
 
 async function inputSelectCluster(input: MultiStepInput, state: Partial<CreateTopicState>, clusterSettings: ClusterSettings, clientAccessor: ClientAccessor) {
+    //reset total steps
+    state.totalSteps = 4;
     interface ClusterPickItem extends QuickPickItem {
         clusterId: string;
     }
@@ -114,6 +125,10 @@ async function inputSelectCluster(input: MultiStepInput, state: Partial<CreateTo
         activeItem: activeClusterItem
     }));
     state.clusterId = selectedCluster.clusterId;
+    state.maxReplicas = await getMaxReplicas(clientAccessor, state.clusterId!);
+    if (state.maxReplicas <= 1) {
+        state.totalSteps = state.totalSteps! -1;
+    }
     return (input: MultiStepInput) => inputTopicName(input, state, clientAccessor);
 }
 
@@ -135,7 +150,7 @@ async function inputTopicName(input: MultiStepInput, state: Partial<CreateTopicS
 }
 
 async function getExistingTopicNames(clientAccessor: ClientAccessor, clusterId?: string): Promise<string[] | undefined> {
-    if (!clusterId) {return [];}
+    if (!clusterId) { return []; }
     try {
         const client = clientAccessor.get(clusterId);
         return (await client.getTopics()).map(topic => topic.id);
@@ -160,12 +175,44 @@ async function inputPartitions(input: MultiStepInput, state: Partial<CreateTopic
 
 
 async function inputReplicationFactor(input: MultiStepInput, state: Partial<CreateTopicState>) {
+    if (state.maxReplicas! <= 1) {
+        state.replicationFactor = state.maxReplicas!.toString();
+        return;
+    }
     state.replicationFactor = await input.showInputBox({
         title: INPUT_TITLE,
         step: input.getStepNumber(),
         totalSteps: state.totalSteps,
-        value: state.replicationFactor || DEFAULT_REPLICATION_FACTOR.toString(),
+        value: state.replicationFactor || state.maxReplicas!.toString(),
         prompt: 'Replication Factor',
         validate: validateReplicationFactor
     });
 }
+async function getMaxReplicas(clientAccessor: ClientAccessor, clusterId: string): Promise<number> {
+    const client = clientAccessor.get(clusterId);
+    const brokers = await client.getBrokers();
+    let replicationFactor = -1;
+    if (brokers) {
+        try {
+            for (let i = 0; i < brokers.length && replicationFactor < 0; i++) {
+                const configs = await client.getBrokerConfigs(brokers[i].id);
+                let config = configs.find(ce => ce.configName === REPLICATION_FACTOR_KEY);
+                if (config) {
+                    replicationFactor = parseInt(config.configValue, 10);
+                } else {
+                    config = configs.find(ce => ce.configName === DEFAULT_REPLICATION_FACTOR_KEY);
+                    if (config) {
+                        replicationFactor = parseInt(config.configValue, 10);
+                    }
+                }
+            }
+        } catch (e) {
+            console.log(`Failed to read replication factor configuration from broker: `+e.message);
+        }
+        if (replicationFactor < 0) {
+            replicationFactor = Math.min(3, brokers.length);
+        }
+    }
+    return replicationFactor;
+}
+