Chapter 18. Requesting CRI-O and Kubelet profiling data by using the Node Observability Operator
Chapter 18. Requesting CRI-O and Kubelet profiling data by using the Node Observability Operator The Node Observability Operator collects and stores the CRI-O and Kubelet profiling data of worker nodes. You can query the profiling data to analyze the CRI-O and Kubelet performance trends and debug the performance-related issues. Important The Node Observability Operator 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 Technology Preview Features Support Scope . 18.1. Workflow of the Node Observability Operator The following workflow outlines on how to query the profiling data using the Node Observability Operator: Install the Node Observability Operator in the OpenShift Container Platform cluster. Create a NodeObservability custom resource to enable the CRI-O profiling on the worker nodes of your choice. Run the profiling query to generate the profiling data. 18.2. Installing the Node Observability Operator The Node Observability Operator is not installed in OpenShift Container Platform by default. You can install the Node Observability Operator by using the OpenShift Container Platform CLI or the web console. 18.2.1. Installing the Node Observability Operator using the CLI You can install the Node Observability Operator by using the OpenShift CLI (oc). Prerequisites You have installed the OpenShift CLI (oc). You have access to the cluster with cluster-admin privileges. Procedure Confirm that the Node Observability Operator is available by running the following command: USD oc get packagemanifests -n openshift-marketplace node-observability-operator Example output NAME CATALOG AGE node-observability-operator Red Hat Operators 9h Create the node-observability-operator namespace by running the following command: USD oc new-project node-observability-operator Create an OperatorGroup object YAML file: cat <<EOF | oc apply -f - apiVersion: operators.coreos.com/v1 kind: OperatorGroup metadata: name: node-observability-operator namespace: node-observability-operator spec: targetNamespaces: [] EOF Create a Subscription object YAML file to subscribe a namespace to an Operator: cat <<EOF | oc apply -f - apiVersion: operators.coreos.com/v1alpha1 kind: Subscription metadata: name: node-observability-operator namespace: node-observability-operator spec: channel: alpha name: node-observability-operator source: redhat-operators sourceNamespace: openshift-marketplace EOF Verification View the install plan name by running the following command: USD oc -n node-observability-operator get sub node-observability-operator -o yaml | yq '.status.installplan.name' Example output install-dt54w Verify the install plan status by running the following command: USD oc -n node-observability-operator get ip <install_plan_name> -o yaml | yq '.status.phase' <install_plan_name> is the install plan name that you obtained from the output of the command. Example output COMPLETE Verify that the Node Observability Operator is up and running: USD oc get deploy -n node-observability-operator Example output NAME READY UP-TO-DATE AVAILABLE AGE node-observability-operator-controller-manager 1/1 1 1 40h 18.2.2. Installing the Node Observability Operator using the web console You can install the Node Observability Operator from the OpenShift Container Platform web console. Prerequisites You have access to the cluster with cluster-admin privileges. You have access to the OpenShift Container Platform web console. Procedure Log in to the OpenShift Container Platform web console. In the Administrator's navigation panel, expand Operators OperatorHub . In the All items field, enter Node Observability Operator and select the Node Observability Operator tile. Click Install . On the Install Operator page, configure the following settings: In the Update channel area, click alpha . In the Installation mode area, click A specific namespace on the cluster . From the Installed Namespace list, select node-observability-operator from the list. In the Update approval area, select Automatic . Click Install . Verification In the Administrator's navigation panel, expand Operators Installed Operators . Verify that the Node Observability Operator is listed in the Operators list. 18.3. Creating the Node Observability custom resource You must create and run the NodeObservability custom resource (CR) before you run the profiling query. When you run the NodeObservability CR, it creates the necessary machine config and machine config pool CRs to enable the CRI-O profiling on the worker nodes matching the nodeSelector . Important If CRI-O profiling is not enabled on the worker nodes, the NodeObservabilityMachineConfig resource gets created. Worker nodes matching the nodeSelector specified in NodeObservability CR restarts. This might take 10 or more minutes to complete. Note Kubelet profiling is enabled by default. The CRI-O unix socket of the node is mounted on the agent pod, which allows the agent to communicate with CRI-O to run the pprof request. Similarly, the kubelet-serving-ca certificate chain is mounted on the agent pod, which allows secure communication between the agent and node's kubelet endpoint. Prerequisites You have installed the Node Observability Operator. You have installed the OpenShift CLI (oc). You have access to the cluster with cluster-admin privileges. Procedure Log in to the OpenShift Container Platform CLI by running the following command: USD oc login -u kubeadmin https://<HOSTNAME>:6443 Switch back to the node-observability-operator namespace by running the following command: USD oc project node-observability-operator Create a CR file named nodeobservability.yaml that contains the following text: apiVersion: nodeobservability.olm.openshift.io/v1alpha2 kind: NodeObservability metadata: name: cluster 1 spec: nodeSelector: kubernetes.io/hostname: <node_hostname> 2 type: crio-kubelet 1 You must specify the name as cluster because there should be only one NodeObservability CR per cluster. 2 Specify the nodes on which the Node Observability agent must be deployed. Run the NodeObservability CR: oc apply -f nodeobservability.yaml Example output nodeobservability.olm.openshift.io/cluster created Review the status of the NodeObservability CR by running the following command: USD oc get nob/cluster -o yaml | yq '.status.conditions' Example output conditions: conditions: - lastTransitionTime: "2022-07-05T07:33:54Z" message: 'DaemonSet node-observability-ds ready: true NodeObservabilityMachineConfig ready: true' reason: Ready status: "True" type: Ready NodeObservability CR run is completed when the reason is Ready and the status is True . 18.4. Running the profiling query To run the profiling query, you must create a NodeObservabilityRun resource. The profiling query is a blocking operation that fetches CRI-O and Kubelet profiling data for a duration of 30 seconds. After the profiling query is complete, you must retrieve the profiling data inside the container file system /run/node-observability directory. The lifetime of data is bound to the agent pod through the emptyDir volume, so you can access the profiling data while the agent pod is in the running status. Important You can request only one profiling query at any point of time. Prerequisites You have installed the Node Observability Operator. You have created the NodeObservability custom resource (CR). You have access to the cluster with cluster-admin privileges. Procedure Create a NodeObservabilityRun resource file named nodeobservabilityrun.yaml that contains the following text: apiVersion: nodeobservability.olm.openshift.io/v1alpha2 kind: NodeObservabilityRun metadata: name: nodeobservabilityrun spec: nodeObservabilityRef: name: cluster Trigger the profiling query by running the NodeObservabilityRun resource: USD oc apply -f nodeobservabilityrun.yaml Review the status of the NodeObservabilityRun by running the following command: USD oc get nodeobservabilityrun nodeobservabilityrun -o yaml | yq '.status.conditions' Example output conditions: - lastTransitionTime: "2022-07-07T14:57:34Z" message: Ready to start profiling reason: Ready status: "True" type: Ready - lastTransitionTime: "2022-07-07T14:58:10Z" message: Profiling query done reason: Finished status: "True" type: Finished The profiling query is complete once the status is True and type is Finished . Retrieve the profiling data from the container's /run/node-observability path by running the following bash script: for a in USD(oc get nodeobservabilityrun nodeobservabilityrun -o yaml | yq .status.agents[].name); do echo "agent USD{a}" mkdir -p "/tmp/USD{a}" for p in USD(oc exec "USD{a}" -c node-observability-agent -- bash -c "ls /run/node-observability/*.pprof"); do f="USD(basename USD{p})" echo "copying USD{f} to /tmp/USD{a}/USD{f}" oc exec "USD{a}" -c node-observability-agent -- cat "USD{p}" > "/tmp/USD{a}/USD{f}" done done
oc get packagemanifests -n openshift-marketplace node-observability-operator NAME CATALOG AGE node-observability-operator Red Hat Operators 9h oc new-project node-observability-operator cat <<EOF | oc apply -f - apiVersion: operators.coreos.com/v1 kind: OperatorGroup metadata: name: node-observability-operator namespace: node-observability-operator spec: targetNamespaces: [] EOF cat <<EOF | oc apply -f - apiVersion: operators.coreos.com/v1alpha1 kind: Subscription metadata: name: node-observability-operator namespace: node-observability-operator spec: channel: alpha name: node-observability-operator source: redhat-operators sourceNamespace: openshift-marketplace EOF oc -n node-observability-operator get sub node-observability-operator -o yaml | yq '.status.installplan.name' install-dt54w oc -n node-observability-operator get ip <install_plan_name> -o yaml | yq '.status.phase' COMPLETE oc get deploy -n node-observability-operator NAME READY UP-TO-DATE AVAILABLE AGE node-observability-operator-controller-manager 1/1 1 1 40h oc login -u kubeadmin https://<HOSTNAME>:6443 oc project node-observability-operator apiVersion: nodeobservability.olm.openshift.io/v1alpha2 kind: NodeObservability metadata: name: cluster 1 spec: nodeSelector: kubernetes.io/hostname: <node_hostname> 2 type: crio-kubelet apply -f nodeobservability.yaml nodeobservability.olm.openshift.io/cluster created oc get nob/cluster -o yaml | yq '.status.conditions' conditions: conditions: - lastTransitionTime: "2022-07-05T07:33:54Z" message: 'DaemonSet node-observability-ds ready: true NodeObservabilityMachineConfig ready: true' reason: Ready status: "True" type: Ready apiVersion: nodeobservability.olm.openshift.io/v1alpha2 kind: NodeObservabilityRun metadata: name: nodeobservabilityrun spec: nodeObservabilityRef: name: cluster oc apply -f nodeobservabilityrun.yaml oc get nodeobservabilityrun nodeobservabilityrun -o yaml | yq '.status.conditions' conditions: - lastTransitionTime: "2022-07-07T14:57:34Z" message: Ready to start profiling reason: Ready status: "True" type: Ready - lastTransitionTime: "2022-07-07T14:58:10Z" message: Profiling query done reason: Finished status: "True" type: Finished for a in USD(oc get nodeobservabilityrun nodeobservabilityrun -o yaml | yq .status.agents[].name); do echo "agent USD{a}" mkdir -p "/tmp/USD{a}" for p in USD(oc exec "USD{a}" -c node-observability-agent -- bash -c "ls /run/node-observability/*.pprof"); do f="USD(basename USD{p})" echo "copying USD{f} to /tmp/USD{a}/USD{f}" oc exec "USD{a}" -c node-observability-agent -- cat "USD{p}" > "/tmp/USD{a}/USD{f}" done done