add a second elasticache connection for dual write

zendesk · May 31, 2024 · f9e8dce · f9e8dce
1 parent 6f70974
commit f9e8dce
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Showing 4 changed files with 96 additions and 6 deletions.
diff --git a/lib/connection.js b/lib/connection.js
@@ -21,6 +21,7 @@ function Connection (name, config) {
     enableReadyCheck: true
   }
   this.client = null
+  this.replicaClient = null
   this.subscriber = null
   this.readyListeners = []
   this.teardownListeners = []
@@ -63,6 +64,10 @@ Connection.prototype.connectMethod = function (config, callback) {
   }
 }
 
+Connection.prototype.connectReplicaMethod = function (config, callback) {
+  this.connectRedis(config.redisReplicaUrl, callback, true)
+}
+
 Connection.prototype.establish = function (ready) {
   ready = ready || function () {}
   const self = this
@@ -87,6 +92,18 @@ Connection.prototype.establish = function (ready) {
       self.client = client
     }))
 
+    if (process.env.RADAR_MIGRATION_ENABLED === 'true') {
+      // create a client (read/write)
+      this.connectReplicaMethod(this.config, tracker('client ready :' + this.name, function (error, replicaClient) {
+        if (error) {
+          throw (error instanceof Error) ? error : new Error(error)
+        }
+
+        logging.info('Created new read/write replicaClient client.')
+        self.replicaClient = replicaClient
+      }))
+    }
+
     // create a pubsub client
     this.connectMethod(this.config, tracker('subscriber ready :' + this.name, function (error, subscriber) {
       if (error) {
@@ -128,8 +145,8 @@ Connection.prototype.teardown = function (callback) {
   }
 }
 
-Connection.prototype.connectRedis = function (config, callback) {
-  var client = new Redis({
+Connection.prototype.connectRedis = function (config, callback, isReplica = false) {
+  let client = new Redis({
     port: config.port,
     host: config.host,
     enableReadyCheck: true,
@@ -151,7 +168,11 @@ Connection.prototype.connectRedis = function (config, callback) {
   }
 
   client.on('ready', function () {
-    logging.info('Redis client "ready" event.')
+    if (isReplica) {
+      logging.info('Redis Replica client "ready" event.')
+    } else {
+      logging.info('Redis client "ready" event.')
+    }
     callback(null, client)
   })
 

diff --git a/package-lock.json b/package-lock.json
diff --git a/package.json b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "persistence",
-  "version": "2.1.0",
+  "version": "2.1.1",
   "description": "An abstraction library for redis and sentinel connection management",
   "main": "lib/index.js",
   "scripts": {

diff --git a/test/connection.test.js b/test/connection.test.js
@@ -2,6 +2,10 @@ const assert = require('assert')
 const ConnectionHelper = require('../lib/connection_helper.js')
 const SentinelHelper = require('simple_sentinel')
 
+beforeEach(function () {
+  process.env.RADAR_MIGRATION_ENABLED = 'false'
+})
+
 describe('given a ConnectionHelper', function () {
   const configuration = {
     connection_settings: {
@@ -104,6 +108,71 @@ describe('given a ConnectionHelper', function () {
       })
     })
 
+    it('should connect to both Redis and Replica', function (done) {
+      process.env.RADAR_MIGRATION_ENABLED = 'true'
+      const configurationWithReplica = {
+        connection_settings: {
+          main: {
+            redisReplicaUrl: parseUrl('redis://localhost:26379'),
+            redis: {
+              host: 'localhost',
+              port: 16379
+            },
+            sentinel: {
+              // sentinel master name is required
+              id: 'mymaster',
+              sentinels: [
+                {
+                  host: 'localhost',
+                  port: 26379
+                },
+                {
+                  host: 'localhost',
+                  port: 26380
+                },
+                {
+                  host: 'localhost',
+                  port: 26381
+                }]
+            }
+          }
+        }
+      }
+      const config = JSON.parse(JSON.stringify(configurationWithReplica))
+      config.use_connection = 'main'
+      const connection = ConnectionHelper.connection(config)
+      connection.establish(function (ready) {
+        assert.equal(connection.client.status, 'ready')
+        assert.equal(connection.replicaClient.status, 'ready')
+        connection.teardown(function () {
+          ConnectionHelper.destroyConnection(config, done)
+        })
+      })
+    })
+
+    function parseUrl (redisUrl) {
+      const urlParser = require('url')
+      const parsedUrl = new urlParser.URL(redisUrl)
+      console.log('parsedUrl: ', parsedUrl)
+      console.log('hostname: ', parsedUrl.hostname)
+      console.log('port: ', parsedUrl.port)
+      const config = {
+        host: parsedUrl.hostname,
+        port: parsedUrl.port
+      }
+
+      if (parsedUrl.auth) {
+        // the password part of user:pass format
+        config.redis_auth = parsedUrl.auth.substr(parsedUrl.auth.indexOf(':') + 1)
+      }
+
+      if (redisUrl.startsWith('rediss://')) {
+        config.tls = {}
+      }
+
+      return config
+    }
+
     it('should reuse existing connection', function (done) {
       const config = JSON.parse(JSON.stringify(configuration))
       config.use_connection = 'sentinel'