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120 lines
2.8 KiB
Plaintext
120 lines
2.8 KiB
Plaintext
// Module included in the following assemblies:
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//
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// * nodes/nodes-cluster-resource-levels.adoc
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:_mod-docs-content-type: PROCEDURE
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[id="nodes-cluster-resource-levels-command_{context}"]
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= Running the OpenShift Cluster Capacity Tool on the command line
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[role="_abstract"]
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You can run the OpenShift Cluster Capacity Tool from the command line to estimate the number of pods that can be scheduled onto your cluster.
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You create a sample pod spec file, which the tool uses for estimating resource usage. The pod spec specifies its resource requirements as `limits` or `requests`. The cluster capacity tool takes the pod's resource requirements into account for its estimation analysis.
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.Prerequisites
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. Run the OpenShift Cluster Capacity Tool, which is available as a container image from the Red Hat Ecosystem Catalog. See the link in the "Additional resources" section.
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. Create a sample pod spec file:
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.. Create a YAML file similar to the following:
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+
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[source,yaml]
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----
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apiVersion: v1
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kind: Pod
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metadata:
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name: small-pod
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labels:
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app: guestbook
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tier: frontend
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spec:
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securityContext:
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runAsNonRoot: true
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seccompProfile:
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type: RuntimeDefault
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containers:
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- name: php-redis
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image: gcr.io/google-samples/gb-frontend:v4
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imagePullPolicy: Always
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resources:
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limits:
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cpu: 150m
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memory: 100Mi
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requests:
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cpu: 150m
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memory: 100Mi
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securityContext:
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allowPrivilegeEscalation: false
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capabilities:
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drop: [ALL]
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----
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.. Create the cluster role:
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+
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[source,terminal]
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----
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$ oc create -f <file_name>.yaml
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----
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For example:
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+
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[source,terminal]
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----
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$ oc create -f pod-spec.yaml
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----
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.Procedure
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. From the terminal, log in to the Red Hat Registry:
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+
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[source,terminal]
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----
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$ podman login registry.redhat.io
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----
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. Pull the cluster capacity tool image:
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+
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[source,terminal]
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----
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$ podman pull registry.redhat.io/openshift4/ose-cluster-capacity
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----
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. Run the cluster capacity tool:
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+
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[source,terminal]
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----
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$ podman run -v $HOME/.kube:/kube:Z -v $(pwd):/cc:Z ose-cluster-capacity \
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/bin/cluster-capacity --kubeconfig /kube/config --<pod_spec>.yaml /cc/<pod_spec>.yaml \
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--verbose
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----
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+
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--
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where:
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<pod_spec>.yaml:: Specifies the pod spec to use.
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verbose:: Outputs a detailed description of how many pods can be scheduled on each node in the cluster.
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--
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+
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.Example output
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[source,terminal]
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----
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small-pod pod requirements:
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- CPU: 150m
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- Memory: 100Mi
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The cluster can schedule 88 instance(s) of the pod small-pod.
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Termination reason: Unschedulable: 0/5 nodes are available: 2 Insufficient cpu,
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3 node(s) had taint {node-role.kubernetes.io/master: }, that the pod didn't
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tolerate.
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Pod distribution among nodes:
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small-pod
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- 192.168.124.214: 45 instance(s)
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- 192.168.124.120: 43 instance(s)
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----
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+
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In the above example, the number of estimated pods that can be scheduled onto
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the cluster is 88.
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