Managing metrics

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:0.3.0
        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

Apply the configuration to the cluster:

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

You can check that the pod is running:

$ oc -n ns1 get pod

NAME                                      READY     STATUS    RESTARTS   AGE
prometheus-example-app-7857545cb7-sbgwq   1/1       Running   0          81m

Create a YAML file for the serviceMonitor resource configuration. In this example, the file is called example-app-service-monitor.yaml.

Add the following serviceMonitor resource configuration details:

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

Apply the configuration to the cluster:

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

You can check that the serviceMonitor resource is running:

$ oc -n ns1 get servicemonitor

NAME                         AGE
prometheus-example-monitor   81m

In the Administrator perspective within the OpenShift Container Platform web console, select Monitoring → Metrics.

Select Insert Metric at Cursor to view a list of predefined queries.

To create a custom query, add your Prometheus Query Language (PromQL) query to the Expression field.

To add multiple queries, select Add Query.

To delete a query, select next to the query, then choose Delete query.

To disable a query from being run, select next to the query and choose Disable query.

Select Run Queries to run the queries that you have created. The metrics from the queries are visualized on the plot. If a query is invalid, the UI shows an error message.

Optional: The page URL now contains the queries you ran. To use this set of queries again in the future, save this URL.

From the Developer perspective in the OpenShift Container Platform web console, select Monitoring → Metrics.

Select the project that you want to view metrics for in the Project: list.

Choose a query from the Select Query list, or run a custom PromQL query by selecting Show PromQL.

Initially, all metrics from all enabled queries are shown on the plot. You can select which metrics are shown.

To zoom into the plot and change the time range, do one of the following:

To reset the time range, select Reset Zoom.

To display outputs for all queries at a specific point in time, hold the mouse cursor on the plot at that point. The query outputs will appear in a pop-up box.

To hide the plot, select Hide Graph.

To zoom into the plot and change the time range, do one of the following:

To reset the time range, select Reset Zoom.

To display outputs for all queries at a specific point in time, hold the mouse cursor on the plot at that point. The query outputs will appear in a pop-up box.