Chapter 4. Configuring the Cluster Observability Operator to monitor a service

Procedure

1. Create a YAML file named prometheus-coo-example-app.yaml that contains the following configuration details for a namespace, deployment, and service:

   apiVersion: v1
   kind: Namespace
   metadata:
     name: ns1-coo
   ---
   apiVersion: apps/v1
   kind: Deployment
   metadata:
     labels:
       app: prometheus-coo-example-app
     name: prometheus-coo-example-app
     namespace: ns1-coo
   spec:
     replicas: 1
     selector:
       matchLabels:
         app: prometheus-coo-example-app
     template:
       metadata:
         labels:
           app: prometheus-coo-example-app
       spec:
         containers:
         - image: ghcr.io/rhobs/prometheus-example-app:0.4.2
           imagePullPolicy: IfNotPresent
           name: prometheus-coo-example-app
   ---
   apiVersion: v1
   kind: Service
   metadata:
     labels:
       app: prometheus-coo-example-app
     name: prometheus-coo-example-app
     namespace: ns1-coo
   spec:
     ports:
     - port: 8080
       protocol: TCP
       targetPort: 8080
       name: web
     selector:
       app: prometheus-coo-example-app
     type: ClusterIP

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2. Save the file.

3. Apply the configuration to the cluster by running the following command:

   $ oc apply -f prometheus-coo-example-app.yaml

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4. Verify that the pod is running by running the following command and observing the output:

   $ oc -n ns1-coo get pod

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   Example output

   NAME                                      READY     STATUS    RESTARTS   AGE
   prometheus-coo-example-app-0927545cb7-anskj   1/1       Running   0          81m

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Procedure

1. Create a YAML file named example-coo-app-service-monitor.yaml that contains the following ServiceMonitor object configuration details:

   apiVersion: monitoring.rhobs/v1
   kind: ServiceMonitor
   metadata:
     labels:
       k8s-app: prometheus-coo-example-monitor
     name: prometheus-coo-example-monitor
     namespace: ns1-coo
   spec:
     endpoints:
     - interval: 30s
       port: web
       scheme: http
     selector:
       matchLabels:
         app: prometheus-coo-example-app

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   This configuration defines a ServiceMonitor object that the MonitoringStack object will reference to scrape the metrics data exposed by the prometheus-coo-example-app sample service.

2. Apply the configuration to the cluster by running the following command:

   $ oc apply -f example-coo-app-service-monitor.yaml

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3. Verify that the ServiceMonitor resource is created by running the following command and observing the output:

   $ oc -n ns1-coo get servicemonitors.monitoring.rhobs

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   Example output

   NAME                         AGE
   prometheus-coo-example-monitor   81m

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Procedure

1. Create a YAML file for the MonitoringStack object configuration. For this example, name the file example-coo-monitoring-stack.yaml.

2. Add the following MonitoringStack object configuration details:

   Example MonitoringStack object

   apiVersion: monitoring.rhobs/v1alpha1
   kind: MonitoringStack
   metadata:
     name: example-coo-monitoring-stack
     namespace: ns1-coo
   spec:
     logLevel: debug
     retention: 1d
     resourceSelector:
       matchLabels:
         k8s-app: prometheus-coo-example-monitor

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3. Apply the MonitoringStack object by running the following command:

   $ oc apply -f example-coo-monitoring-stack.yaml

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4. Verify that the MonitoringStack object is available by running the following command and inspecting the output:

   $ oc -n ns1-coo get monitoringstack

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   Example output

   NAME                         AGE
   example-coo-monitoring-stack   81m

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5. Run the following comand to retrieve information about the active targets from Prometheus and filter the output to list only targets labeled with app=prometheus-coo-example-app. This verifies which targets are discovered and actively monitored by Prometheus with this specific label.

   $ oc -n ns1-coo exec -c prometheus prometheus-example-coo-monitoring-stack-0 -- curl -s 'http://localhost:9090/api/v1/targets' | jq '.data.activeTargets[].discoveredLabels | select(.__meta_kubernetes_endpoints_label_app=="prometheus-coo-example-app")'

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   Example output

   {
     "__address__": "10.129.2.25:8080",
     "__meta_kubernetes_endpoint_address_target_kind": "Pod",
     "__meta_kubernetes_endpoint_address_target_name": "prometheus-coo-example-app-5d8cd498c7-9j2gj",
     "__meta_kubernetes_endpoint_node_name": "ci-ln-8tt8vxb-72292-6cxjr-worker-a-wdfnz",
     "__meta_kubernetes_endpoint_port_name": "web",
     "__meta_kubernetes_endpoint_port_protocol": "TCP",
     "__meta_kubernetes_endpoint_ready": "true",
     "__meta_kubernetes_endpoints_annotation_endpoints_kubernetes_io_last_change_trigger_time": "2024-11-05T11:24:09Z",
     "__meta_kubernetes_endpoints_annotationpresent_endpoints_kubernetes_io_last_change_trigger_time": "true",
     "__meta_kubernetes_endpoints_label_app": "prometheus-coo-example-app",
     "__meta_kubernetes_endpoints_labelpresent_app": "true",
     "__meta_kubernetes_endpoints_name": "prometheus-coo-example-app",
     "__meta_kubernetes_namespace": "ns1-coo",
     "__meta_kubernetes_pod_annotation_k8s_ovn_org_pod_networks": "{\"default\":{\"ip_addresses\":[\"10.129.2.25/23\"],\"mac_address\":\"0a:58:0a:81:02:19\",\"gateway_ips\":[\"10.129.2.1\"],\"routes\":[{\"dest\":\"10.128.0.0/14\",\"nextHop\":\"10.129.2.1\"},{\"dest\":\"172.30.0.0/16\",\"nextHop\":\"10.129.2.1\"},{\"dest\":\"100.64.0.0/16\",\"nextHop\":\"10.129.2.1\"}],\"ip_address\":\"10.129.2.25/23\",\"gateway_ip\":\"10.129.2.1\",\"role\":\"primary\"}}",
     "__meta_kubernetes_pod_annotation_k8s_v1_cni_cncf_io_network_status": "[{\n    \"name\": \"ovn-kubernetes\",\n    \"interface\": \"eth0\",\n    \"ips\": [\n        \"10.129.2.25\"\n    ],\n    \"mac\": \"0a:58:0a:81:02:19\",\n    \"default\": true,\n    \"dns\": {}\n}]",
     "__meta_kubernetes_pod_annotation_openshift_io_scc": "restricted-v2",
     "__meta_kubernetes_pod_annotation_seccomp_security_alpha_kubernetes_io_pod": "runtime/default",
     "__meta_kubernetes_pod_annotationpresent_k8s_ovn_org_pod_networks": "true",
     "__meta_kubernetes_pod_annotationpresent_k8s_v1_cni_cncf_io_network_status": "true",
     "__meta_kubernetes_pod_annotationpresent_openshift_io_scc": "true",
     "__meta_kubernetes_pod_annotationpresent_seccomp_security_alpha_kubernetes_io_pod": "true",
     "__meta_kubernetes_pod_controller_kind": "ReplicaSet",
     "__meta_kubernetes_pod_controller_name": "prometheus-coo-example-app-5d8cd498c7",
     "__meta_kubernetes_pod_host_ip": "10.0.128.2",
     "__meta_kubernetes_pod_ip": "10.129.2.25",
     "__meta_kubernetes_pod_label_app": "prometheus-coo-example-app",
     "__meta_kubernetes_pod_label_pod_template_hash": "5d8cd498c7",
     "__meta_kubernetes_pod_labelpresent_app": "true",
     "__meta_kubernetes_pod_labelpresent_pod_template_hash": "true",
     "__meta_kubernetes_pod_name": "prometheus-coo-example-app-5d8cd498c7-9j2gj",
     "__meta_kubernetes_pod_node_name": "ci-ln-8tt8vxb-72292-6cxjr-worker-a-wdfnz",
     "__meta_kubernetes_pod_phase": "Running",
     "__meta_kubernetes_pod_ready": "true",
     "__meta_kubernetes_pod_uid": "054c11b6-9a76-4827-a860-47f3a4596871",
     "__meta_kubernetes_service_label_app": "prometheus-coo-example-app",
     "__meta_kubernetes_service_labelpresent_app": "true",
     "__meta_kubernetes_service_name": "prometheus-coo-example-app",
     "__metrics_path__": "/metrics",
     "__scheme__": "http",
     "__scrape_interval__": "30s",
     "__scrape_timeout__": "10s",
     "job": "serviceMonitor/ns1-coo/prometheus-coo-example-monitor/0"
   }

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   Note

   The above example uses jq command-line JSON processor to format the output for convenience.

Procedure

1. Create a route to expose the example prometheus-coo-example-app service. From your terminal, run the command:

   $ oc expose svc prometheus-coo-example-app -n ns1-coo

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2. Access the route from your browser, or command line, to generate metrics.

3. Execute a query on the Prometheus pod to return the total HTTP requests metric:

   $ oc -n ns1-coo exec -c prometheus prometheus-example-coo-monitoring-stack-0 -- curl -s 'http://localhost:9090/api/v1/query?query=http_requests_total'

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   Example output (formatted using jq for convenience)

   {
     "status": "success",
     "data": {
       "resultType": "vector",
       "result": [
         {
           "metric": {
             "__name__": "http_requests_total",
             "code": "200",
             "endpoint": "web",
             "instance": "10.129.2.25:8080",
             "job": "prometheus-coo-example-app",
             "method": "get",
             "namespace": "ns1-coo",
             "pod": "prometheus-coo-example-app-5d8cd498c7-9j2gj",
             "service": "prometheus-coo-example-app"
           },
           "value": [
             1730807483.632,
             "3"
           ]
         },
         {
           "metric": {
             "__name__": "http_requests_total",
             "code": "404",
             "endpoint": "web",
             "instance": "10.129.2.25:8080",
             "job": "prometheus-coo-example-app",
             "method": "get",
             "namespace": "ns1-coo",
             "pod": "prometheus-coo-example-app-5d8cd498c7-9j2gj",
             "service": "prometheus-coo-example-app"
           },
           "value": [
             1730807483.632,
             "0"
           ]
         }
       ]
     }
   }

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Procedure

1. Deploy the following namespace object and MonitoringStack YAML file:

   Example MonitoringStack

   apiVersion: v1
   kind: Namespace
   metadata:
     name: ns1-coo
     labels:
       monitoring.rhobs/stack: multi-ns
   ---
   apiVersion: monitoring.rhobs/v1alpha1
   kind: MonitoringStack
   metadata:
     name: example-coo-monitoring-stack
     namespace: ns1-coo
   spec:
     logLevel: debug
     retention: 1d
     resourceSelector:
         matchLabels:
           k8s-app: prometheus-coo-example-monitor
     namespaceSelector:
         matchLabels:
           monitoring.rhobs/stack: multi-ns

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2. Deploy a sample application in the namespace ns1-coo, with an alert that is always firing:

   apiVersion: apps/v1
   kind: Deployment
   metadata:
     labels:
       app: prometheus-coo-example-app
     name: prometheus-coo-example-app
     namespace: ns1-coo
   spec:
     replicas: 1
     selector:
       matchLabels:
         app: prometheus-coo-example-app
     template:
       metadata:
         labels:
           app: prometheus-coo-example-app
       spec:
         containers:
         - image: ghcr.io/rhobs/prometheus-example-app:0.4.2
           imagePullPolicy: IfNotPresent
           name: prometheus-coo-example-app
   ---
   apiVersion: v1
   kind: Service
   metadata:
     labels:
       app: prometheus-coo-example-app
     name: prometheus-coo-example-app
     namespace: ns1-coo
   spec:
     ports:
     - port: 8080
       protocol: TCP
       targetPort: 8080
       name: web
     selector:
       app: prometheus-coo-example-app
     type: ClusterIP
   ---
   apiVersion: monitoring.rhobs/v1
   kind: ServiceMonitor
   metadata:
     labels:
       k8s-app: prometheus-coo-example-monitor
     name: prometheus-coo-example-monitor
     namespace: ns1-coo
   spec:
     endpoints:
     - interval: 30s
       port: web
       scheme: http
     selector:
       matchLabels:
         app: prometheus-coo-example-app
   ---
   apiVersion: monitoring.rhobs/v1
   kind: PrometheusRule
   metadata:
     name: example-alert
     namespace: ns1-coo
     labels:
       k8s-app: prometheus-coo-example-monitor
   spec:
     groups:
     - name: example
       rules:
       - alert: VersionAlert
         for: 1m
         expr: version{job="prometheus-coo-example-app"} > 0
         labels:
           severity: warning

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3. Deploy the same example application in another namespace labeled with monitoring.rhobs/stack: multi-ns:

   apiVersion: v1
   kind: Namespace
   metadata:
     name: ns2-coo
     labels:
       monitoring.rhobs/stack: multi-ns
   ---
   apiVersion: apps/v1
   kind: Deployment
   metadata:
     labels:
       app: prometheus-coo-example-app
     name: prometheus-coo-example-app
     namespace: ns2-coo
   spec:
     replicas: 1
     selector:
       matchLabels:
         app: prometheus-coo-example-app
     template:
       metadata:
         labels:
           app: prometheus-coo-example-app
       spec:
         containers:
         - image: ghcr.io/rhobs/prometheus-example-app:0.4.2
           imagePullPolicy: IfNotPresent
           name: prometheus-coo-example-app
   ---
   apiVersion: v1
   kind: Service
   metadata:
     labels:
       app: prometheus-coo-example-app
     name: prometheus-coo-example-app
     namespace: ns2-coo
   spec:
     ports:
     - port: 8080
       protocol: TCP
       targetPort: 8080
       name: web
     selector:
       app: prometheus-coo-example-app
     type: ClusterIP
   ---
   apiVersion: monitoring.rhobs/v1
   kind: ServiceMonitor
   metadata:
     labels:
       k8s-app: prometheus-coo-example-monitor
     name: prometheus-coo-example-monitor
     namespace: ns2-coo
   spec:
     endpoints:
     - interval: 30s
       port: web
       scheme: http
     selector:
       matchLabels:
         app: prometheus-coo-example-app

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Verification

1. Verify that the Prometheus instance adds new targets and that the alert are firing. Use a port-forward command to expose the Prometheus or the Alertmanager user interface that has been deployed by the Monitoringstack instance.

   Prometheus

   $ oc port-forward -n ns1-coo pod/prometheus-example-coo-monitoring-stack-0 9090

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   Alertmanager

   $ oc port-forward -n ns1-coo pod/alertmanager-example-coo-monitoring-stack-0 9093

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2. Verify that the targets are being scraped and that the alerts are firing by browsing to http://localhost:9090/targets or http://localhost:9093/#/alerts.