redis.service.ts

redis.service.tsapps/api/src/common/redis.service.tsraw ← common2,225 B← Back to the app
1import { Injectable, OnModuleDestroy, OnModuleInit } from "@nestjs/common";
2import Redis from "ioredis";
3import { loadEnv } from "../config/env.js";
4import { logger } from "./logger.js";
5 
6/**
7 * Redis (ioredis) provider. Connection errors log and degrade (services
8 * treat Redis as optional: rate limiting opens up, events still publish
9 * in-process) — the API must not crash-loop when Redis blips.
10 */
11@Injectable()
12export class RedisService implements OnModuleInit, OnModuleDestroy {
13  private readonly client: Redis;
14 
15  constructor() {
16    this.client = new Redis(loadEnv().REDIS_URL, {
17      maxRetriesPerRequest: 2,
18      retryStrategy: (times: number) => Math.min(times * 500, 5000)
19    });
20  }
21 
22  onModuleInit(): void {
23    this.client.on("error", (err: Error) => {
24      logger.warn(`redis error: ${err.message}`);
25    });
26    this.client.on("connect", () => logger.info("redis connected"));
27  }
28 
29  /** The underlying ioredis instance. */
30  getRedis(): Redis {
31    return this.client;
32  }
33 
34  /**
35   * Run a callback on a duplicated connection with `subscribe` applied —
36   * ioredis clients cannot mix pub/sub and regular commands on one socket.
37   * Returns an unsubscribe() handle.
38   */
39  async subscribe(channel: string, handler: (message: string) => void): Promise<() => Promise<void>> {
40    const sub = this.client.duplicate();
41    sub.on("error", () => undefined); // subscriber errors are non-fatal
42    // ioredis types the subscribe callback as `Callback<unknown>`
43    // (`(err?, result?) => void`); the runtime forwards the reply through it.
44    // The `as never` cast keeps this call runtime-identical to the original
45    // `sub.subscribe(channel, handler)` (type-only reconciliation, no
46    // behavioral change).
47    await sub.subscribe(channel, handler as never);
48    return async () => {
49      await sub.unsubscribe(channel).catch(() => undefined);
50      sub.disconnect();
51    };
52  }
53 
54  /** Best-effort PING (used by /health/deep). */
55  async ping(): Promise<boolean> {
56    try {
57      return (await this.client.ping()) === "PONG";
58    } catch {
59      return false;
60    }
61  }
62 
63  async onModuleDestroy(): Promise<void> {
64    await this.client.quit().catch(() => this.client.disconnect());
65  }
66}
67