feat(GOV-009): 建立后端契约与健康检查

server/apps/api/src/health.service.ts

@@ -0,0 +1,51 @@
+import { Inject, Injectable } from '@nestjs/common';
+
+import type {
+  DependencyHealthDto,
+  HealthResponseDto,
+} from '../../../libs/http-contracts/src/health.dto';
+
+export const REDIS_HEALTH_PORT = Symbol('REDIS_HEALTH_PORT');
+export const MYSQL_HEALTH_PORT = Symbol('MYSQL_HEALTH_PORT');
+
+export interface DependencyHealthPort {
+  check(): Promise<DependencyHealthDto>;
+}
+
+@Injectable()
+export class HealthService {
+  constructor(
+    @Inject(REDIS_HEALTH_PORT) private readonly redis: DependencyHealthPort,
+    @Inject(MYSQL_HEALTH_PORT) private readonly mysql: DependencyHealthPort,
+  ) {}
+
+  async check(): Promise<HealthResponseDto> {
+    const [redis, mysql] = await Promise.all([
+      this.checkSafely(this.redis),
+      this.checkSafely(this.mysql),
+    ]);
+    const status =
+      redis.status === 'healthy' && mysql.status !== 'unavailable' ? 'healthy' : 'unavailable';
+
+    return {
+      status,
+      process: 'api',
+      checkedAt: new Date().toISOString(),
+      dependencies: {
+        redis,
+        mysql,
+        rocketMq: { status: 'disabled', detail: 'GOV-009 尚未启用 RocketMQ 客户端' },
+      },
+    };
+  }
+
+  private async checkSafely(port: DependencyHealthPort): Promise<DependencyHealthDto> {
+    try {
+      const result = await port.check();
+      if (result.status === 'healthy' || result.status === 'disabled') return result;
+    } catch {
+      // 外部错误可能包含 DSN、用户名或密码；HTTP 健康响应只暴露固定安全文案。
+    }
+    return { status: 'unavailable', detail: '依赖检查失败' };
+  }
+}