The Cluster Monitoring Operator manages and updates the Prometheus-based cluster monitoring stack deployed on top of OpenShift.

It contains the following components:

• Prometheus Operator
• Prometheus
• Alertmanager cluster for cluster and application level alerting
• kube-state-metrics
• node_exporter

The deployed Prometheus Operator is intended to be used only for cluster-level monitoring. As such, the deployed Prometheus instance (prometheus-k8s) is responsible for monitoring and alerting on cluster and OpenShift components; it should not be extended to monitor user applications. Important: The Prometheus Operator managed by the Cluster Monitoring Operator will by default only look for ServiceMonitor resources in openshift-monitoring namespace.

Users interested in leveraging Prometheus for application monitoring on OpenShift should consider using OLM to easily deploy a Prometheus Operator and setup new Prometheus instances to monitor and alert on their applications.

Alertmanager is a cluster-global component for handling alerts generated by all Prometheus instances deployed in that cluster.

Metrics are collected from the following components:

• kube-state-metrics
• node_exporter
• Kubelets
• API server
• Prometheus (just prometheus-k8s for now)
• Alertmanager
• Telemeter

The Cluster Monitoring Operator has many builtin ServiceMonitor resources which enable discovering the metrics endpoints of a variety of well-known components. Only components that must be created before the cluster monitoring stack belong in this repository, in order to solve the cyclic dependencies of bootstrapping.

To register a new builtin component, make the following changes:

• Add a new ServiceMonitor manifest file to jsonnet/prometheus.jsonnet. An example of this can be seen for the OpenShift component "kube-controllers", here.
• Re-generate the go-bindata code, using the pkg/manifests/bindata.go make target. This will also create a new file in assets/prometheus-k8s/ according to the name given in the jsonnet code.
• Add a constant in pkg/manifests/manifests.go which points to the new manifest file, from assets/.
• Add a new Factory method in pkg/manifests/manifests.go which loads the manifest using the new constant.
• Add a step to PrometheusTask in pkg/tasks/prometheus.go which creates the ServiceMonitor using the Factory new method.

To add new builtin recording or alerting rules:

• Add a new Prometheus rules file to jsonnet/rules.jsonnet.

Run make pkg/manifests/bindata.go after you modify the files and make sure to add the modified files to the commit. All rules are automatically created, so no additional code changes are necessary.

• Monitor etcd
• Adapt Tectonic inherited alerts with OpenShift operational knowledge

Run e2e-tests with make e2e-test. Clean up after e2e-tests with make e2e-clean