fix: mikroorm is indicated as up even when disconnected

e2e/health-checks/mikro-orm.health.e2e-spec.ts

@@ -1,3 +1,4 @@
+import { MikroORM } from '@mikro-orm/core';
 import { type INestApplication } from '@nestjs/common';
 import * as request from 'supertest';
 import {
@@ -76,6 +77,42 @@ describe('MikroOrmHealthIndicator', () => {
           details,
         });
       });
+
+      it('should indicate that mikroOrm is down if the connection has been closed after startup', async () => {
+        app = await setHealthEndpoint(({ healthCheck, mikroOrm }) =>
+          healthCheck.check([async () => mikroOrm.pingCheck('mikroOrm')]),
+        ).start();
+
+        const up = {
+          mikroOrm: {
+            status: 'up',
+          },
+        };
+
+        request(app.getHttpServer()).get('/health').expect(200).expect({
+          status: 'ok',
+          info: up,
+          error: {},
+          details: up,
+        });
+
+        const orm = app.get(MikroORM);
+        await orm.close();
+
+        const down = {
+          mikroOrm: {
+            status: 'down',
+            message: 'Not connected to database',
+          },
+        };
+
+        return request(app.getHttpServer()).get('/health').expect(503).expect({
+          status: 'error',
+          info: {},
+          error: down,
+          details: down,
+        });
+      });
     });
   });
 

lib/errors/database-not-connected.error.ts

@@ -0,0 +1,11 @@
+import { DATABASE_NOT_CONNECTED } from './messages.constant';
+
+/**
+ * Error which gets thrown when the database is not connected
+ * @publicApi
+ */
+export class DatabaseNotConnectedError extends Error {
+  constructor() {
+    super(DATABASE_NOT_CONNECTED);
+  }
+}

lib/errors/messages.constant.ts

@@ -8,7 +8,7 @@ export const CONNECTION_NOT_FOUND =
  * @internal
  */
 export const TIMEOUT_EXCEEDED = (timeout: number) =>
-  `timeout of ${timeout.toString()}ms exceeded`;
+  `Timeout of ${timeout.toString()}ms exceeded`;
 
 /**
  * @internal
@@ -21,3 +21,8 @@ export const STORAGE_EXCEEDED = (keyword: string) =>
  */
 export const UNHEALTHY_RESPONSE_CODE = (responseCode: string | number) =>
   `The service returned an unhealthy response code: ${responseCode}`;
+
+/**
+ * @internal
+ */
+export const DATABASE_NOT_CONNECTED = `Not connected to database`;

lib/health-indicator/database/mikro-orm.health.ts

@@ -3,7 +3,8 @@ import { Injectable, Scope } from '@nestjs/common';
 import { ModuleRef } from '@nestjs/core';
 import { HealthIndicator, type HealthIndicatorResult } from '..';
 import { TimeoutError } from '../../errors';
-import { HealthCheckError } from '../../health-check';
+import { DatabaseNotConnectedError } from '../../errors/database-not-connected.error';
+import { HealthCheckError } from '../../health-check/health-check.error';
 import {
   TimeoutError as PromiseTimeoutError,
   promiseTimeout,
@@ -74,16 +75,19 @@ export class MikroOrmHealthIndicator extends HealthIndicator {
           }),
         );
       }
-
-      // Check if the error is a connection not found error
-      if (error instanceof Error) {
+      if (error instanceof DatabaseNotConnectedError) {
         throw new HealthCheckError(
           error.message,
           this.getStatus(key, false, {
             message: error.message,
           }),
         );
       }
+
+      throw new HealthCheckError(
+        `${key} is not available`,
+        this.getStatus(key, false),
+      );
     }
 
     return this.getStatus(key, true);
@@ -120,7 +124,13 @@ export class MikroOrmHealthIndicator extends HealthIndicator {
    *
    */
   private async pingDb(connection: MikroOrm.Connection, timeout: number) {
-    const isConnected = connection.isConnected();
-    return await promiseTimeout(timeout, isConnected);
+    const checker = async () => {
+      const isConnected = await connection.isConnected();
+      if (!isConnected) {
+        throw new DatabaseNotConnectedError();
+      }
+    };
+
+    return await promiseTimeout(timeout, checker());
   }
 }