add collecting Prometheus metrics fot the tldraw app

ansible/roles/schulcloud-server-core/tasks/main.yml

@@ -207,3 +207,10 @@
       template: tldraw-ingress.yml.j2
       apply: yes
     when: WITH_TLDRAW is defined and WITH_TLDRAW|bool
+
+  - name: TldrawServiceMonitor
+    kubernetes.core.k8s:
+      kubeconfig: ~/.kube/config
+      namespace: "{{ NAMESPACE }}"
+      template: tldraw-svc-monitor.yml.j2
+    when: WITH_TLDRAW is defined and WITH_TLDRAW|bool

ansible/roles/schulcloud-server-core/templates/tldraw-deployment.yml.j2

@@ -52,6 +52,9 @@ spec:
         - containerPort: 3349
           name: tldraw-http
           protocol: TCP
+        - containerPort: 9090
+          name: api-metrics
+          protocol: TCP
         envFrom:
         - configMapRef:
             name: api-configmap

ansible/roles/schulcloud-server-core/templates/tldraw-server-svc.yml.j2

@@ -18,5 +18,9 @@ spec:
       targetPort: 3349
       protocol: TCP
       name: tldraw-http
+    - port: {{ PORT_METRICS_SERVER }}
+      targetPort: 9090
+      protocol: TCP
+      name: api-metrics
   selector:
     app: tldraw-server

ansible/roles/schulcloud-server-core/templates/tldraw-svc-monitor.yml.j2

@@ -0,0 +1,17 @@
+apiVersion: monitoring.coreos.com/v1
+kind: ServiceMonitor
+metadata:
+  name: tldraw-svc-monitor
+  namespace: {{ NAMESPACE }}
+  labels:
+    app: tldraw-server
+spec:
+  selector:
+    matchExpressions:
+      - key: app.kubernetes.io/name
+        operator: in
+        values:
+          - tldraw-server-svc
+  endpoints:
+  - path: /metrics
+    port: api-metrics

apps/server/src/apps/tldraw.app.ts

@@ -10,6 +10,10 @@ import { enableOpenApiDocs } from '@shared/controller/swagger';
 import { AppStartLoggable } from '@src/apps/helpers/app-start-loggable';
 import { ExpressAdapter } from '@nestjs/platform-express';
 import express from 'express';
+import {
+	addPrometheusMetricsMiddlewaresIfEnabled,
+	createAndStartPrometheusMetricsAppIfEnabled,
+} from '@src/apps/helpers/prometheus-metrics';
 
 async function bootstrap() {
 	sourceMapInstall();
@@ -33,18 +37,23 @@ async function bootstrap() {
 	// mount instances
 	const rootExpress = express();
 
+	addPrometheusMetricsMiddlewaresIfEnabled(logger, rootExpress);
 	const port = 3349;
 	const basePath = '/api/v3';
 
 	// exposed alias mounts
 	rootExpress.use(basePath, nestExpress);
-	rootExpress.listen(port);
 
-	logger.info(
-		new AppStartLoggable({
-			appName: 'Tldraw server app',
-		})
-	);
+	rootExpress.listen(port, () => {
+		logger.info(
+			new AppStartLoggable({
+				appName: 'Tldraw server app',
+				port,
+			})
+		);
+
+		createAndStartPrometheusMetricsAppIfEnabled(logger);
+	});
 }
 
 void bootstrap();