feat: ✨ support connection retries with exponential backoff for redis and databases

Author: simplymichael

src/component/connector/mongoose.js

@@ -1,6 +1,7 @@
 const util = require("node:util");
 const mongoose = require("mongoose");
 const debug = require("../../lib/debug");
+const { sleep } = require("../../lib/util");
 const validateConnectionOptions = require("./connection-validator");
 
 
@@ -44,11 +45,12 @@ module.exports = class MongooseStore {
    * @return {resource} a (mongoose) connection instance
    */
   async connect() {
+    let dsn;
+    let attempts = 0;
     const options = this.#options;
+    const maxAttempts = this.#options.maxConnectionAttempts || 5;
     const { host, port, username, password, dbName, enableDebugging } = options;
 
-    let dsn;
-
     if(options.url?.trim()?.length > 0) {
       dsn = options.url;
     } else {
@@ -67,16 +69,28 @@ module.exports = class MongooseStore {
 
     mongoose.set("debug", enableDebugging);
 
-    try {
-      debug("Connecting to MongoDB...");
+    while(attempts < maxAttempts) {
+      try {
+        debug("Connecting to MongoDB...");
 
-      this.#db = mongoose.createConnection(dsn, {});
+        this.#db = mongoose.createConnection(dsn, {});
 
-      debug("MongoDB connection established");
+        debug("MongoDB connection established");
 
-      return this.#db;
-    } catch(e) {
-      debug(`Mongoose connection error: ${util.inspect(e)}`);
+        return this.#db;
+      } catch(e) {
+        attempts++;
+
+        debug(`Mongoose connection error: ${util.inspect(e)}`);
+        debug(`Retrying connection to MongoDB (${attempts}/${maxAttempts}) attempts`);
+
+        if(attempts === maxAttempts) {
+          debug(`Failed to connect to MongoDB after ${maxAttempts} attempts. Exiting...`);
+          process.exit(1);
+        }
+
+        await sleep(1000 * attempts); // Exponential backoff
+      }
     }
   }
 
@@ -145,6 +159,10 @@ module.exports = class MongooseStore {
 
     debug("Mongoose connection options validated.");
 
-    return { ...validatedOptions, url: options?.url };
+    return {
+      ...validatedOptions,
+      url: options?.url,
+      maxConnectionAttempts: options?.maxConnectionAttempts,
+    };
   }
 };

src/component/connector/redis.js

@@ -1,6 +1,7 @@
 const redis  = require("redis");
 const util = require("node:util");
 const debug = require("../../lib/debug");
+const { sleep } = require("../../lib/util");
 const validateConnectionOptions = require("./connection-validator");
 
 
@@ -45,14 +46,30 @@ module.exports = class RedisStore {
       );
     }
 
-    try {
-      debug("Connecting to Redis...");
+    let attempts = 0;
+    const client = this.getClient();
+    const maxAttempts = this.#options.maxConnectionAttempts || 5;
 
-      await this.getClient()?.connect();
+    while(attempts < maxAttempts) {
+      try {
+        debug("Connecting to Redis...");
 
-      debug("Redis connection established.");
-    } catch(e) {
-      debug(`Redis connection error: ${util.inspect(e)}`);
+        await client.connect();
+
+        debug("Redis connection established.");
+      } catch(e) {
+        attempts++;
+
+        debug(`Redis connection error: ${util.inspect(e)}`);
+        debug(`Retrying connection to Redis (${attempts}/${maxAttempts}) attempts`);
+
+        if(attempts === maxAttempts) {
+          debug(`Failed to connect to Redis after ${maxAttempts} attempts. Exiting...`);
+          process.exit(1);
+        }
+
+        await sleep(1000 * attempts); // Exponential backoff
+      }
     }
   }
 
@@ -199,6 +216,10 @@ module.exports = class RedisStore {
 
     debug("Redis connection options validated.");
 
-    return { ...validatedOptions, url: options?.url };
+    return {
+      ...validatedOptions,
+      url: options?.url,
+      maxConnectionAttempts: options?.maxConnectionAttempts,
+    };
   }
 };

src/component/connector/sequelize.js

@@ -1,6 +1,7 @@
 const util = require("node:util");
 const { Sequelize } = require("sequelize");
 const debug = require("../../lib/debug");
+const { sleep } = require("../../lib/util");
 const validateConnectionOptions = require("./connection-validator");
 
 
@@ -110,18 +111,32 @@ module.exports = class SequelizeStore {
    * @return {resource} a (mongoose) connection instance
    */
   async connect() {
+    let attempts = 0;
+    const maxAttempts = this.#options.maxConnectionAttempts || 5;
     const dbEngine = this.#dbEngine;
 
-    try {
-      this.#debug(`Connecting to ${dbEngine}...`);
+    while(attempts < maxAttempts) {
+      try {
+        this.#debug(`Connecting to ${dbEngine}...`);
 
-      await this.#db.authenticate();
+        await this.#db.authenticate();
 
-      this.#connected = true;
+        this.#connected = true;
 
-      this.#debug(`${dbEngine} connection established`);
-    } catch(e) {
-      this.#debug(`Sequelize connection error: ${util.inspect(e)}`);
+        this.#debug(`${dbEngine} connection established`);
+      } catch(e) {
+        attempts++;
+
+        this.#debug(`Sequelize connection error: ${util.inspect(e)}`);
+        this.#debug(`Retrying connection to ${dbEngine} (${attempts}/${maxAttempts}) attempts`);
+
+        if(attempts === maxAttempts) {
+          this.#debug(`Failed to connect to ${dbEngine} after ${maxAttempts} attempts. Exiting...`);
+          process.exit(1);
+        }
+
+        await sleep(1000 * attempts); // Exponential backoff
+      }
     }
 
     return this.#db;
@@ -187,7 +202,11 @@ module.exports = class SequelizeStore {
 
     this.#debug("Sequelize connection options validated.");
 
-    return validatedOptions;
+    return {
+      ...validatedOptions,
+      url: options.url,
+      maxConnectionAttempts: options.maxConnectionAttempts
+    };
   }
 
   #debug(message) {

src/factory/cache/redis-cache.js

@@ -20,6 +20,8 @@ const RedisStore = require("../../component/connector/redis");
  * @param {String} [options.credentials.url]: full DSN of the Redis server
  *   If the [options.credentials.url] is set, it is used instead
  *   and the other credential options are ignored.
+ * @param {Number} [options.maxConnectionAttempts]: The maximum number of times
+ *   to attempt connecting before exiting.
  * @return {Object} with methods: set(), get(), unset(), contains(), and client().
  */
 module.exports = function createRedisStore(options) {

src/lib/util.js

@@ -0,0 +1,9 @@
+"use strict";
+
+module.exports = {
+  sleep,
+};
+
+function sleep(ms) {
+  return new Promise(resolve => setTimeout(resolve, ms));
+}