feat(api): add health check endpoints with @nestjs/terminus

Add HealthModule with /health (liveness) and /ready (readiness) probes.
Readiness checks DB (Prisma) and Redis connectivity.
Replaces the basic /health endpoint in AppController.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/api/src/modules/health/health.controller.ts

@@ -0,0 +1,33 @@
+import { Controller, Get } from '@nestjs/common';
+// eslint-disable-next-line @typescript-eslint/consistent-type-imports
+import { HealthCheck, HealthCheckService } from '@nestjs/terminus';
+// eslint-disable-next-line @typescript-eslint/consistent-type-imports
+import { PrismaHealthIndicator } from './infrastructure/prisma.health';
+// eslint-disable-next-line @typescript-eslint/consistent-type-imports
+import { RedisHealthIndicator } from './infrastructure/redis.health';
+
+@Controller()
+export class HealthController {
+  constructor(
+    private readonly health: HealthCheckService,
+    private readonly prismaHealth: PrismaHealthIndicator,
+    private readonly redisHealth: RedisHealthIndicator,
+  ) {}
+
+  /** Liveness probe — always returns 200 if the process is running */
+  @Get('health')
+  @HealthCheck()
+  liveness() {
+    return this.health.check([]);
+  }
+
+  /** Readiness probe — checks DB and Redis connectivity */
+  @Get('ready')
+  @HealthCheck()
+  readiness() {
+    return this.health.check([
+      () => this.prismaHealth.isHealthy('database'),
+      () => this.redisHealth.isHealthy('redis'),
+    ]);
+  }
+}

apps/api/src/modules/health/health.module.ts

@@ -0,0 +1,12 @@
+import { Module } from '@nestjs/common';
+import { TerminusModule } from '@nestjs/terminus';
+import { HealthController } from './health.controller';
+import { PrismaHealthIndicator } from './infrastructure/prisma.health';
+import { RedisHealthIndicator } from './infrastructure/redis.health';
+
+@Module({
+  imports: [TerminusModule],
+  controllers: [HealthController],
+  providers: [PrismaHealthIndicator, RedisHealthIndicator],
+})
+export class HealthModule {}

apps/api/src/modules/health/index.ts

@@ -0,0 +1 @@
+export { HealthModule } from './health.module';

apps/api/src/modules/health/infrastructure/prisma.health.ts

@@ -0,0 +1,20 @@
+import { Injectable } from '@nestjs/common';
+import { HealthCheckError, HealthIndicator, type HealthIndicatorResult } from '@nestjs/terminus';
+// eslint-disable-next-line @typescript-eslint/consistent-type-imports
+import { PrismaService } from '@modules/shared/infrastructure/prisma.service';
+
+@Injectable()
+export class PrismaHealthIndicator extends HealthIndicator {
+  constructor(private readonly prisma: PrismaService) {
+    super();
+  }
+
+  async isHealthy(key: string): Promise<HealthIndicatorResult> {
+    try {
+      await this.prisma.$queryRawUnsafe('SELECT 1');
+      return this.getStatus(key, true);
+    } catch {
+      throw new HealthCheckError('Database check failed', this.getStatus(key, false));
+    }
+  }
+}

apps/api/src/modules/health/infrastructure/redis.health.ts

@@ -0,0 +1,25 @@
+import { Injectable } from '@nestjs/common';
+import { HealthCheckError, HealthIndicator, type HealthIndicatorResult } from '@nestjs/terminus';
+// eslint-disable-next-line @typescript-eslint/consistent-type-imports
+import { RedisService } from '@modules/shared/infrastructure/redis.service';
+
+@Injectable()
+export class RedisHealthIndicator extends HealthIndicator {
+  constructor(private readonly redis: RedisService) {
+    super();
+  }
+
+  async isHealthy(key: string): Promise<HealthIndicatorResult> {
+    try {
+      const client = this.redis.getClient();
+      const pong = await client.ping();
+      const isHealthy = pong === 'PONG';
+      const result = this.getStatus(key, isHealthy);
+      if (isHealthy) return result;
+      throw new HealthCheckError('Redis ping failed', result);
+    } catch (error) {
+      if (error instanceof HealthCheckError) throw error;
+      throw new HealthCheckError('Redis check failed', this.getStatus(key, false));
+    }
+  }
+}