Monitoring KubeVirt components

All KubeVirt system-components expose Prometheus metrics at their /metrics REST endpoint.

Custom Service Discovery

Prometheus supports service discovery based on Pods and Endpoints out of the box. Both can be used to discover KubeVirt services.

All Pods which expose metrics are labeled with prometheus.kubevirt.io and contain a port-definition which is called metrics. In the KubeVirt release-manifests, the default metrics port is 8443.

The above labels and port informations are collected by a Service called kubevirt-prometheus-metrics. Kuberentes automatically creates a corresponding Endpoint with an equal name:

$ kubectl get endpoints -n kubevirt kubevirt-prometheus-metrics -o yaml
apiVersion: v1
kind: Endpoints
metadata:
  labels:
    kubevirt.io: ""
    prometheus.kubevirt.io: ""
  name: kubevirt-prometheus-metrics
  namespace: kubevirt
subsets:
- addresses:
  - ip: 10.244.0.5
    nodeName: node01
    targetRef:
      kind: Pod
      name: virt-handler-cjzg6
      namespace: kubevirt
      resourceVersion: "4891"
      uid: c67331f9-bfcf-11e8-bc54-525500d15501
  - ip: 10.244.0.6
  [...]
  ports:
  - name: metrics
    port: 8443
    protocol: TCP

By watching this endpoint for added and removed IPs to subsets.addresses and appending the metrics port from subsets.ports, it is possible to always get a complete list of ready-to-be-scraped Prometheus targets.

Integrating with the prometheus-operator

The prometheus-operator can make use of the kubevirt-prometheus-metrics service to automatically create the appropriate Prometheus config.

KubeVirt’s virt-operator checks if the ServiceMonitor custom resource exists when creating an install strategy for deployment. KubeVirt will automatically create a ServiceMonitor resource in the monitorNamespace, as well as an appropriate role and rolebinding in KubeVirt’s namespace.

Two settings are exposed in the KubeVirt custom resource to direct KubeVirt to create these resources correctly:

  • monitorNamespace: The namespace that prometheus-operator runs in. Defaults to openshift-monitoring.

  • monitorAccount: The serviceAccount that prometheus-operator runs with. Defaults to prometheus-k8s.

If the prometheus-operator for a given deployment uses these defaults, then these values can be omitted.

An example of the KubeVirt resource depicting these default values:

apiVersion: kubevirt.io/v1alpha3
kind: KubeVirt
metadata:
  name: kubevirt
spec:
  monitorNamespace: openshift-monitoring
  monitorAccount: prometheus-k8s

Integrating with the OKD cluster-monitoring-operator

After the cluster-monitoring-operator is up and running, KubeVirt will detect the existence of the ServiceMonitor resource. Because the definition contains the openshift.io/cluster-monitoring label, it will automatically be picked up by the cluster monitor.

Metrics about Virtual Machines

The endpoints report metrics related to the runtime behaviour of the Virtual Machines. All the relevant metrics are prefixed with kubevirt_vmi.

The metrics have labels that allow to connect to the VMI objects they refer to. At minimum, the labels will expose node, name and namespace of the related VMI object.

For example, reported metrics could look like

kubevirt_vmi_memory_resident_bytes{domain="default_vm-test-01",name="vm-test-01",namespace="default",node="node01"} 2.5595904e+07
kubevirt_vmi_network_traffic_bytes_total{domain="default_vm-test-01",interface="vnet0",name="vm-test-01",namespace="default",node="node01",type="rx"} 8431
kubevirt_vmi_network_traffic_bytes_total{domain="default_vm-test-01",interface="vnet0",name="vm-test-01",namespace="default",node="node01",type="tx"} 1835
kubevirt_vmi_vcpu_seconds{domain="default_vm-test-01",id="0",name="vm-test-01",namespace="default",node="node01",state="1"} 19

Please note the domain label in the above example. This label is deprecated and it will be removed in a future release. You should identify the VMI using the node, namespace, name labels instead.

Important Queries

Detecting connection issues for the REST client

Use the following query to get a counter for all REST call which indicate connection issues:

rest_client_requests_total{code="<error>"}

If this counter is continuously increasing, it is an indicator that the corresponding KubeVirt component has general issues to connect to the apiserver