Retry failed connection attempts

app/src/bolt/bolt.service.ts

@@ -1,4 +1,4 @@
-import { Injectable } from "@nestjs/common";
+import { Injectable, Logger } from "@nestjs/common";
 import { App, LogLevel } from "@slack/bolt";
 import { StringIndexed } from "@slack/bolt/dist/types/helpers";
 import { ConfigService } from "../common/config/config.service";
@@ -7,23 +7,24 @@ import { BoltLogger } from "./bolt-logger";
 @Injectable()
 export class BoltService {
   private bolt: App<StringIndexed>;
+  private logger = new Logger(BoltService.name);
 
   constructor(private configService: ConfigService) {}
 
   async connect() {
     const { appToken, token, signingSecret } = this.configService.getConfig().bolt;
-    const logger = new BoltLogger();
+    const boltLogger = new BoltLogger();
 
     this.bolt = new App({
       appToken,
       token,
       signingSecret,
       socketMode: true,
-      logger,
+      logger: boltLogger,
       logLevel: LogLevel.INFO,
     });
 
-    await this.bolt.start();
+    await this.connectWithRetry();
   }
 
   async disconnect() {
@@ -33,4 +34,19 @@ export class BoltService {
   getBolt(): App<StringIndexed> {
     return this.bolt;
   }
+
+  private async connectWithRetry(): Promise<void> {
+    // eslint-disable-next-line no-constant-condition
+    while (true) {
+      try {
+        await this.bolt.start();
+        return;
+      } catch (error) {
+        this.logger.error("Failed to initialize a connection to Slack.", error);
+        this.logger.log("Trying to connect again to Slack.");
+
+        await new Promise((resolve) => setTimeout(resolve, 2000));
+      }
+    }
+  }
 }