Chapter 7. Managing metrics You can collect metrics to monitor how cluster components and your own workloads are performing. 7.1. Understanding metrics In OpenShift Container Platform 4.12, cluster components are monitored by scraping metrics exposed through service endpoints. You can also configure metrics collection for user-defined projects. You can define the metrics that you want to provide for your own workloads by using Prometheus client libraries at the application level. In OpenShift Container Platform, metrics are exposed through an HTTP service endpoint under the /metrics canonical name. You can list all available metrics for a service by running a curl query against http://<endpoint>/metrics . For instance, you can expose a route to the prometheus-example-app example service and then run the following to view all of its available metrics: USD curl http://<example_app_endpoint>/metrics Example output # HELP http_requests_total Count of all HTTP requests # TYPE http_requests_total counter http_requests_total{code="200",method="get"} 4 http_requests_total{code="404",method="get"} 2 # HELP version Version information about this binary # TYPE version gauge version{version="v0.1.0"} 1 Additional resources Prometheus client library documentation 7.2. Setting up metrics collection for user-defined projects You can create a ServiceMonitor resource to scrape metrics from a service endpoint in a user-defined project. This assumes that your application uses a Prometheus client library to expose metrics to the /metrics canonical name. This section describes how to deploy a sample service in a user-defined project and then create a ServiceMonitor resource that defines how that service should be monitored. 7.2.1. Deploying a sample service To test monitoring of a service in a user-defined project, you can deploy a sample service. Prerequisites You have access to the cluster as a user with the cluster-admin cluster role or as a user with administrative permissions for the namespace. Procedure Create a YAML file for the service configuration. In this example, it is called prometheus-example-app.yaml . Add the following deployment and service configuration details to the file: apiVersion: v1 kind: Namespace metadata: name: ns1 --- apiVersion: apps/v1 kind: Deployment metadata: labels: app: prometheus-example-app name: prometheus-example-app namespace: ns1 spec: replicas: 1 selector: matchLabels: app: prometheus-example-app template: metadata: labels: app: prometheus-example-app spec: containers: - image: ghcr.io/rhobs/prometheus-example-app:0.4.2 imagePullPolicy: IfNotPresent name: prometheus-example-app --- apiVersion: v1 kind: Service metadata: labels: app: prometheus-example-app name: prometheus-example-app namespace: ns1 spec: ports: - port: 8080 protocol: TCP targetPort: 8080 name: web selector: app: prometheus-example-app type: ClusterIP This configuration deploys a service named prometheus-example-app in the user-defined ns1 project. This service exposes the custom version metric. Apply the configuration to the cluster: USD oc apply -f prometheus-example-app.yaml It takes some time to deploy the service. You can check that the pod is running: USD oc -n ns1 get pod Example output NAME READY STATUS RESTARTS AGE prometheus-example-app-7857545cb7-sbgwq 1/1 Running 0 81m 7.2.2. Specifying how a service is monitored To use the metrics exposed by your service, you must configure OpenShift Container Platform monitoring to scrape metrics from the /metrics endpoint. You can do this using a ServiceMonitor custom resource definition (CRD) that specifies how a service should be monitored, or a PodMonitor CRD that specifies how a pod should be monitored. The former requires a Service object, while the latter does not, allowing Prometheus to directly scrape metrics from the metrics endpoint exposed by a pod. This procedure shows you how to create a ServiceMonitor resource for a service in a user-defined project. Prerequisites You have access to the cluster as a user with the cluster-admin cluster role or the monitoring-edit cluster role. You have enabled monitoring for user-defined projects. For this example, you have deployed the prometheus-example-app sample service in the ns1 project. Note The prometheus-example-app sample service does not support TLS authentication. Procedure Create a new YAML configuration file named example-app-service-monitor.yaml . Add a ServiceMonitor resource to the YAML file. The following example creates a service monitor named prometheus-example-monitor to scrape metrics exposed by the prometheus-example-app service in the ns1 namespace: apiVersion: monitoring.coreos.com/v1 kind: ServiceMonitor metadata: name: prometheus-example-monitor namespace: ns1 1 spec: endpoints: - interval: 30s port: web 2 scheme: http selector: 3 matchLabels: app: prometheus-example-app 1 Specify a user-defined namespace where your service runs. 2 Specify endpoint ports to be scraped by Prometheus. 3 Configure a selector to match your service based on its metadata labels. Note A ServiceMonitor resource in a user-defined namespace can only discover services in the same namespace. That is, the namespaceSelector field of the ServiceMonitor resource is always ignored. Apply the configuration to the cluster: USD oc apply -f example-app-service-monitor.yaml It takes some time to deploy the ServiceMonitor resource. Verify that the ServiceMonitor resource is running: USD oc -n <namespace> get servicemonitor Example output NAME AGE prometheus-example-monitor 81m 7.2.3. Example service endpoint authentication settings You can configure authentication for service endpoints for user-defined project monitoring by using ServiceMonitor and PodMonitor custom resource definitions (CRDs). The following samples show different authentication settings for a ServiceMonitor resource. Each sample shows how to configure a corresponding Secret object that contains authentication credentials and other relevant settings. 7.2.3.1. Sample YAML authentication with a bearer token The following sample shows bearer token settings for a Secret object named example-bearer-auth in the ns1 namespace: Example bearer token secret apiVersion: v1 kind: Secret metadata: name: example-bearer-auth namespace: ns1 stringData: token: <authentication_token> 1 1 Specify an authentication token. The following sample shows bearer token authentication settings for a ServiceMonitor CRD. The example uses a Secret object named example-bearer-auth : Example bearer token authentication settings apiVersion: monitoring.coreos.com/v1 kind: ServiceMonitor metadata: name: prometheus-example-monitor namespace: ns1 spec: endpoints: - authorization: credentials: key: token 1 name: example-bearer-auth 2 port: web selector: matchLabels: app: prometheus-example-app 1 The key that contains the authentication token in the specified Secret object. 2 The name of the Secret object that contains the authentication credentials. Important Do not use bearerTokenFile to configure bearer token. If you use the bearerTokenFile configuration, the ServiceMonitor resource is rejected. 7.2.3.2. Sample YAML for Basic authentication The following sample shows Basic authentication settings for a Secret object named example-basic-auth in the ns1 namespace: Example Basic authentication secret apiVersion: v1 kind: Secret metadata: name: example-basic-auth namespace: ns1 stringData: user: <basic_username> 1 password: <basic_password> 2 1 Specify a username for authentication. 2 Specify a password for authentication. The following sample shows Basic authentication settings for a ServiceMonitor CRD. The example uses a Secret object named example-basic-auth : Example Basic authentication settings apiVersion: monitoring.coreos.com/v1 kind: ServiceMonitor metadata: name: prometheus-example-monitor namespace: ns1 spec: endpoints: - basicAuth: username: key: user 1 name: example-basic-auth 2 password: key: password 3 name: example-basic-auth 4 port: web selector: matchLabels: app: prometheus-example-app 1 The key that contains the username in the specified Secret object. 2 4 The name of the Secret object that contains the Basic authentication. 3 The key that contains the password in the specified Secret object. 7.2.3.3. Sample YAML authentication with OAuth 2.0 The following sample shows OAuth 2.0 settings for a Secret object named example-oauth2 in the ns1 namespace: Example OAuth 2.0 secret apiVersion: v1 kind: Secret metadata: name: example-oauth2 namespace: ns1 stringData: id: <oauth2_id> 1 secret: <oauth2_secret> 2 1 Specify an Oauth 2.0 ID. 2 Specify an Oauth 2.0 secret. The following sample shows OAuth 2.0 authentication settings for a ServiceMonitor CRD. The example uses a Secret object named example-oauth2 : Example OAuth 2.0 authentication settings apiVersion: monitoring.coreos.com/v1 kind: ServiceMonitor metadata: name: prometheus-example-monitor namespace: ns1 spec: endpoints: - oauth2: clientId: secret: key: id 1 name: example-oauth2 2 clientSecret: key: secret 3 name: example-oauth2 4 tokenUrl: https://example.com/oauth2/token 5 port: web selector: matchLabels: app: prometheus-example-app 1 The key that contains the OAuth 2.0 ID in the specified Secret object. 2 4 The name of the Secret object that contains the OAuth 2.0 credentials. 3 The key that contains the OAuth 2.0 secret in the specified Secret object. 5 The URL used to fetch a token with the specified clientId and clientSecret . Additional resources Enabling monitoring for user-defined projects How to scrape metrics using TLS in a ServiceMonitor configuration in a user-defined project PodMonitor API ServiceMonitor API 7.3. Viewing a list of available metrics As a cluster administrator or as a user with view permissions for all projects, you can view a list of metrics available in a cluster and output the list in JSON format. Prerequisites You are a cluster administrator, or you have access to the cluster as a user with the cluster-monitoring-view cluster role. You have installed the OpenShift Container Platform CLI ( oc ). You have obtained the OpenShift Container Platform API route for Thanos Querier. You are able to get a bearer token by using the oc whoami -t command. Important You can only use bearer token authentication to access the Thanos Querier API route. Procedure If you have not obtained the OpenShift Container Platform API route for Thanos Querier, run the following command: USD oc get routes -n openshift-monitoring thanos-querier -o jsonpath='{.status.ingress[0].host}' Retrieve a list of metrics in JSON format from the Thanos Querier API route by running the following command. This command uses oc to authenticate with a bearer token. USD curl -k -H "Authorization: Bearer USD(oc whoami -t)" https://<thanos_querier_route>/api/v1/metadata 1 1 Replace <thanos_querier_route> with the OpenShift Container Platform API route for Thanos Querier.

Commands:
curl http://<example_app_endpoint>/metrics
HELP http_requests_total Count of all HTTP requests TYPE http_requests_total counter http_requests_total{code="200",method="get"} 4 http_requests_total{code="404",method="get"} 2 HELP version Version information about this binary TYPE version gauge version{version="v0.1.0"} 1
apiVersion: v1 kind: Namespace metadata: name: ns1 --- apiVersion: apps/v1 kind: Deployment metadata: labels: app: prometheus-example-app name: prometheus-example-app namespace: ns1 spec: replicas: 1 selector: matchLabels: app: prometheus-example-app template: metadata: labels: app: prometheus-example-app spec: containers: - image: ghcr.io/rhobs/prometheus-example-app:0.4.2 imagePullPolicy: IfNotPresent name: prometheus-example-app --- apiVersion: v1 kind: Service metadata: labels: app: prometheus-example-app name: prometheus-example-app namespace: ns1 spec: ports: - port: 8080 protocol: TCP targetPort: 8080 name: web selector: app: prometheus-example-app type: ClusterIP
oc apply -f prometheus-example-app.yaml
oc -n ns1 get pod
NAME READY STATUS RESTARTS AGE prometheus-example-app-7857545cb7-sbgwq 1/1 Running 0 81m
apiVersion: monitoring.coreos.com/v1 kind: ServiceMonitor metadata: name: prometheus-example-monitor namespace: ns1 1 spec: endpoints: - interval: 30s port: web 2 scheme: http selector: 3 matchLabels: app: prometheus-example-app
oc apply -f example-app-service-monitor.yaml
oc -n <namespace> get servicemonitor
NAME AGE prometheus-example-monitor 81m
apiVersion: v1 kind: Secret metadata: name: example-bearer-auth namespace: ns1 stringData: token: <authentication_token> 1
apiVersion: monitoring.coreos.com/v1 kind: ServiceMonitor metadata: name: prometheus-example-monitor namespace: ns1 spec: endpoints: - authorization: credentials: key: token 1 name: example-bearer-auth 2 port: web selector: matchLabels: app: prometheus-example-app
apiVersion: v1 kind: Secret metadata: name: example-basic-auth namespace: ns1 stringData: user: <basic_username> 1 password: <basic_password> 2
apiVersion: monitoring.coreos.com/v1 kind: ServiceMonitor metadata: name: prometheus-example-monitor namespace: ns1 spec: endpoints: - basicAuth: username: key: user 1 name: example-basic-auth 2 password: key: password 3 name: example-basic-auth 4 port: web selector: matchLabels: app: prometheus-example-app
apiVersion: v1 kind: Secret metadata: name: example-oauth2 namespace: ns1 stringData: id: <oauth2_id> 1 secret: <oauth2_secret> 2
apiVersion: monitoring.coreos.com/v1 kind: ServiceMonitor metadata: name: prometheus-example-monitor namespace: ns1 spec: endpoints: - oauth2: clientId: secret: key: id 1 name: example-oauth2 2 clientSecret: key: secret 3 name: example-oauth2 4 tokenUrl: https://example.com/oauth2/token 5 port: web selector: matchLabels: app: prometheus-example-app
oc get routes -n openshift-monitoring thanos-querier -o jsonpath='{.status.ingress[0].host}'
curl -k -H "Authorization: Bearer USD(oc whoami -t)" https://<thanos_querier_route>/api/v1/metadata 1