Chapter 8. Exposing custom application metrics for autoscaling You can export custom application metrics for the horizontal pod autoscaler. Important Prometheus Adapter is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process. For more information about the support scope of Red Hat Technology Preview features, see https://access.redhat.com/support/offerings/techpreview/ . 8.1. Exposing custom application metrics for horizontal pod autoscaling You can use the prometheus-adapter resource to expose custom application metrics for the horizontal pod autoscaler. Prerequisites You have a custom Prometheus instance installed as a Prometheus pod managed by a deployment or StatefulSet object but not by a Prometheus custom resource (CR). You have installed the custom Prometheus instance in a user-defined custom-prometheus project. Important Custom Prometheus instances and the Prometheus Operator installed through Operator Lifecycle Manager (OLM) are not compatible with user-defined monitoring if it is enabled. Therefore, custom Prometheus instances that are installed as a Prometheus custom resource (CR) managed by the OLM Prometheus Operator are not supported in OpenShift Container Platform. You have deployed an application and a service in a user-defined project. In this example, it is presumed that the application and its service monitor were installed in a user-defined custom-prometheus project. You have installed the OpenShift CLI ( oc ). Procedure Create a YAML file for your configuration. In this example, the file is called deploy.yaml . Add configuration details for creating the service account, roles, and role bindings for prometheus-adapter : kind: ServiceAccount apiVersion: v1 metadata: name: custom-metrics-apiserver namespace: custom-prometheus --- apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRole metadata: name: custom-metrics-server-resources rules: - apiGroups: - custom.metrics.k8s.io resources: ["*"] verbs: ["*"] --- apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRole metadata: name: custom-metrics-resource-reader rules: - apiGroups: - "" resources: - namespaces - pods - services verbs: - get - list --- apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRoleBinding metadata: name: custom-metrics:system:auth-delegator roleRef: apiGroup: rbac.authorization.k8s.io kind: ClusterRole name: system:auth-delegator subjects: - kind: ServiceAccount name: custom-metrics-apiserver namespace: custom-prometheus --- apiVersion: rbac.authorization.k8s.io/v1 kind: RoleBinding metadata: name: custom-metrics-auth-reader namespace: kube-system roleRef: apiGroup: rbac.authorization.k8s.io kind: Role name: extension-apiserver-authentication-reader subjects: - kind: ServiceAccount name: custom-metrics-apiserver namespace: custom-prometheus --- apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRoleBinding metadata: name: custom-metrics-resource-reader roleRef: apiGroup: rbac.authorization.k8s.io kind: ClusterRole name: custom-metrics-resource-reader subjects: - kind: ServiceAccount name: custom-metrics-apiserver namespace: custom-prometheus --- apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRoleBinding metadata: name: hpa-controller-custom-metrics roleRef: apiGroup: rbac.authorization.k8s.io kind: ClusterRole name: custom-metrics-server-resources subjects: - kind: ServiceAccount name: horizontal-pod-autoscaler namespace: kube-system --- Add configuration details for the custom metrics for prometheus-adapter : apiVersion: v1 kind: ConfigMap metadata: name: adapter-config namespace: custom-prometheus data: config.yaml: | rules: - seriesQuery: 'http_requests_total{namespace!="",pod!=""}' 1 resources: overrides: namespace: {resource: "namespace"} pod: {resource: "pod"} service: {resource: "service"} name: matches: "^(.*)_total" as: "USD{1}_per_second" 2 metricsQuery: 'sum(rate(<<.Series>>{<<.LabelMatchers>>}[2m])) by (<<.GroupBy>>)' --- 1 Specifies the chosen metric to be the number of HTTP requests. 2 Specifies the frequency for the metric. Add configuration details for registering prometheus-adapter as an API service: apiVersion: v1 kind: Service metadata: annotations: service.beta.openshift.io/serving-cert-secret-name: prometheus-adapter-tls labels: name: prometheus-adapter name: prometheus-adapter namespace: custom-prometheus spec: ports: - name: https port: 443 targetPort: 6443 selector: app: prometheus-adapter type: ClusterIP --- apiVersion: apiregistration.k8s.io/v1beta1 kind: APIService metadata: name: v1beta1.custom.metrics.k8s.io spec: service: name: prometheus-adapter namespace: custom-prometheus group: custom.metrics.k8s.io version: v1beta1 insecureSkipTLSVerify: true groupPriorityMinimum: 100 versionPriority: 100 --- List the Prometheus Adapter image: USD oc get -n openshift-monitoring deploy/prometheus-adapter -o jsonpath="{..image}" Add configuration details for deploying prometheus-adapter : apiVersion: apps/v1 kind: Deployment metadata: labels: app: prometheus-adapter name: prometheus-adapter namespace: custom-prometheus spec: replicas: 1 selector: matchLabels: app: prometheus-adapter template: metadata: labels: app: prometheus-adapter name: prometheus-adapter spec: serviceAccountName: custom-metrics-apiserver containers: - name: prometheus-adapter image: quay.io/openshift-release-dev/ocp-v4.0-art-dev@sha256:a46915a206cd7d97f240687c618dd59e8848fcc3a0f51e281f3384153a12c3e0 1 args: - --secure-port=6443 - --tls-cert-file=/var/run/serving-cert/tls.crt - --tls-private-key-file=/var/run/serving-cert/tls.key - --logtostderr=true - --prometheus-url=http://prometheus-operated.default.svc:9090/ - --metrics-relist-interval=1m - --v=4 - --config=/etc/adapter/config.yaml ports: - containerPort: 6443 volumeMounts: - mountPath: /var/run/serving-cert name: volume-serving-cert readOnly: true - mountPath: /etc/adapter/ name: config readOnly: true - mountPath: /tmp name: tmp-vol volumes: - name: volume-serving-cert secret: secretName: prometheus-adapter-tls - name: config configMap: name: adapter-config - name: tmp-vol emptyDir: {} 1 Specifies the Prometheus Adapter image found in the step. Apply the configuration to the cluster: USD oc apply -f deploy.yaml Example output serviceaccount/custom-metrics-apiserver created clusterrole.rbac.authorization.k8s.io/custom-metrics-server-resources created clusterrole.rbac.authorization.k8s.io/custom-metrics-resource-reader created clusterrolebinding.rbac.authorization.k8s.io/custom-metrics:system:auth-delegator created rolebinding.rbac.authorization.k8s.io/custom-metrics-auth-reader created clusterrolebinding.rbac.authorization.k8s.io/custom-metrics-resource-reader created clusterrolebinding.rbac.authorization.k8s.io/hpa-controller-custom-metrics created configmap/adapter-config created service/prometheus-adapter created apiservice.apiregistration.k8s.io/v1.custom.metrics.k8s.io created deployment.apps/prometheus-adapter created Verify that the prometheus-adapter pod in your user-defined project is in a Running state. In this example the project is custom-prometheus : USD oc -n custom-prometheus get pods prometheus-adapter-<string> The metrics for the application are now exposed and they can be used to configure horizontal pod autoscaling. Additional resources See the horizontal pod autoscaling documentation See the Kubernetes documentation on horizontal pod autoscaler 8.2. steps Troubleshooting monitoring issues

Commands:
kind: ServiceAccount apiVersion: v1 metadata: name: custom-metrics-apiserver namespace: custom-prometheus --- apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRole metadata: name: custom-metrics-server-resources rules: - apiGroups: - custom.metrics.k8s.io resources: ["*"] verbs: ["*"] --- apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRole metadata: name: custom-metrics-resource-reader rules: - apiGroups: - "" resources: - namespaces - pods - services verbs: - get - list --- apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRoleBinding metadata: name: custom-metrics:system:auth-delegator roleRef: apiGroup: rbac.authorization.k8s.io kind: ClusterRole name: system:auth-delegator subjects: - kind: ServiceAccount name: custom-metrics-apiserver namespace: custom-prometheus --- apiVersion: rbac.authorization.k8s.io/v1 kind: RoleBinding metadata: name: custom-metrics-auth-reader namespace: kube-system roleRef: apiGroup: rbac.authorization.k8s.io kind: Role name: extension-apiserver-authentication-reader subjects: - kind: ServiceAccount name: custom-metrics-apiserver namespace: custom-prometheus --- apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRoleBinding metadata: name: custom-metrics-resource-reader roleRef: apiGroup: rbac.authorization.k8s.io kind: ClusterRole name: custom-metrics-resource-reader subjects: - kind: ServiceAccount name: custom-metrics-apiserver namespace: custom-prometheus --- apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRoleBinding metadata: name: hpa-controller-custom-metrics roleRef: apiGroup: rbac.authorization.k8s.io kind: ClusterRole name: custom-metrics-server-resources subjects: - kind: ServiceAccount name: horizontal-pod-autoscaler namespace: kube-system ---
apiVersion: v1 kind: ConfigMap metadata: name: adapter-config namespace: custom-prometheus data: config.yaml: | rules: - seriesQuery: 'http_requests_total{namespace!="",pod!=""}' 1 resources: overrides: namespace: {resource: "namespace"} pod: {resource: "pod"} service: {resource: "service"} name: matches: "^(.*)_total" as: "USD{1}_per_second" 2 metricsQuery: 'sum(rate(<<.Series>>{<<.LabelMatchers>>}[2m])) by (<<.GroupBy>>)' ---
apiVersion: v1 kind: Service metadata: annotations: service.beta.openshift.io/serving-cert-secret-name: prometheus-adapter-tls labels: name: prometheus-adapter name: prometheus-adapter namespace: custom-prometheus spec: ports: - name: https port: 443 targetPort: 6443 selector: app: prometheus-adapter type: ClusterIP --- apiVersion: apiregistration.k8s.io/v1beta1 kind: APIService metadata: name: v1beta1.custom.metrics.k8s.io spec: service: name: prometheus-adapter namespace: custom-prometheus group: custom.metrics.k8s.io version: v1beta1 insecureSkipTLSVerify: true groupPriorityMinimum: 100 versionPriority: 100 ---
oc get -n openshift-monitoring deploy/prometheus-adapter -o jsonpath="{..image}"
apiVersion: apps/v1 kind: Deployment metadata: labels: app: prometheus-adapter name: prometheus-adapter namespace: custom-prometheus spec: replicas: 1 selector: matchLabels: app: prometheus-adapter template: metadata: labels: app: prometheus-adapter name: prometheus-adapter spec: serviceAccountName: custom-metrics-apiserver containers: - name: prometheus-adapter image: quay.io/openshift-release-dev/ocp-v4.0-art-dev@sha256:a46915a206cd7d97f240687c618dd59e8848fcc3a0f51e281f3384153a12c3e0 1 args: - --secure-port=6443 - --tls-cert-file=/var/run/serving-cert/tls.crt - --tls-private-key-file=/var/run/serving-cert/tls.key - --logtostderr=true - --prometheus-url=http://prometheus-operated.default.svc:9090/ - --metrics-relist-interval=1m - --v=4 - --config=/etc/adapter/config.yaml ports: - containerPort: 6443 volumeMounts: - mountPath: /var/run/serving-cert name: volume-serving-cert readOnly: true - mountPath: /etc/adapter/ name: config readOnly: true - mountPath: /tmp name: tmp-vol volumes: - name: volume-serving-cert secret: secretName: prometheus-adapter-tls - name: config configMap: name: adapter-config - name: tmp-vol emptyDir: {}
oc apply -f deploy.yaml
serviceaccount/custom-metrics-apiserver created clusterrole.rbac.authorization.k8s.io/custom-metrics-server-resources created clusterrole.rbac.authorization.k8s.io/custom-metrics-resource-reader created clusterrolebinding.rbac.authorization.k8s.io/custom-metrics:system:auth-delegator created rolebinding.rbac.authorization.k8s.io/custom-metrics-auth-reader created clusterrolebinding.rbac.authorization.k8s.io/custom-metrics-resource-reader created clusterrolebinding.rbac.authorization.k8s.io/hpa-controller-custom-metrics created configmap/adapter-config created service/prometheus-adapter created apiservice.apiregistration.k8s.io/v1.custom.metrics.k8s.io created deployment.apps/prometheus-adapter created
oc -n custom-prometheus get pods prometheus-adapter-<string>