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163 lines
3.5 KiB
Plaintext
163 lines
3.5 KiB
Plaintext
// Module included in the following assemblies:
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//
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// * nodes/nodes-scheduler-node-affinity.adoc
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[id="nodes-scheduler-pod-affinity-example_{context}"]
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= Sample pod affinity and anti-affinity rules
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The following examples demonstrate pod affinity and pod anti-affinity.
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[id="nodes-scheduler-pod-affinity-example-affinity_{context}"]
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== Pod Affinity
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The following example demonstrates pod affinity for pods with matching labels and label selectors.
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* The pod *team4* has the label `team:4`.
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+
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[source,yaml]
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----
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$ cat team4.yaml
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apiVersion: v1
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kind: Pod
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metadata:
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name: team4
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labels:
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team: "4"
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spec:
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containers:
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- name: ocp
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image: docker.io/ocpqe/hello-pod
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----
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* The pod *team4a* has the label selector `team:4` under `podAffinity`.
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+
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[source,yaml]
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----
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$ cat pod-team4a.yaml
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apiVersion: v1
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kind: Pod
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metadata:
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name: team4a
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spec:
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affinity:
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podAffinity:
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requiredDuringSchedulingIgnoredDuringExecution:
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- labelSelector:
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matchExpressions:
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- key: team
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operator: In
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values:
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- "4"
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topologyKey: kubernetes.io/hostname
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containers:
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- name: pod-affinity
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image: docker.io/ocpqe/hello-pod
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----
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* The *team4a* pod is scheduled on the same node as the *team4* pod.
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[id="nodes-scheduler-pod-affinity-example-antiaffinity_{context}"]
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== Pod Anti-affinity
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The following example demonstrates pod anti-affinity for pods with matching labels and label selectors.
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* The pod *pod-s1* has the label `security:s1`.
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+
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[source,yaml]
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----
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cat pod-s1.yaml
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apiVersion: v1
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kind: Pod
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metadata:
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name: pod-s1
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labels:
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security: s1
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spec:
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containers:
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- name: ocp
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image: docker.io/ocpqe/hello-pod
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----
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* The pod *pod-s2* has the label selector `security:s1` under `podAntiAffinity`.
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+
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[source,yaml]
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----
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cat pod-s2.yaml
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apiVersion: v1
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kind: Pod
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metadata:
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name: pod-s2
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spec:
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affinity:
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podAntiAffinity:
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requiredDuringSchedulingIgnoredDuringExecution:
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- labelSelector:
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matchExpressions:
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- key: security
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operator: In
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values:
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- s1
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topologyKey: kubernetes.io/hostname
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containers:
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- name: pod-antiaffinity
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image: docker.io/ocpqe/hello-pod
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----
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* The pod *pod-s2* cannot be scheduled on the same node as `pod-s1`.
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[id="nodes-scheduler-pod-affinity-example-no-labels_{context}"]
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== Pod Affinity with no Matching Labels
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The following example demonstrates pod affinity for pods without matching labels and label selectors.
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* The pod *pod-s1* has the label `security:s1`.
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[source,yaml]
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----
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$ cat pod-s1.yaml
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apiVersion: v1
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kind: Pod
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metadata:
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name: pod-s1
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labels:
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security: s1
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spec:
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containers:
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- name: ocp
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image: docker.io/ocpqe/hello-pod
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----
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* The pod *pod-s2* has the label selector `security:s2`.
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+
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[source,yaml]
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----
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$ cat pod-s2.yaml
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apiVersion: v1
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kind: Pod
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metadata:
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name: pod-s2
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spec:
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affinity:
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podAffinity:
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requiredDuringSchedulingIgnoredDuringExecution:
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- labelSelector:
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matchExpressions:
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- key: security
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operator: In
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values:
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- s2
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topologyKey: kubernetes.io/hostname
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containers:
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- name: pod-affinity
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image: docker.io/ocpqe/hello-pod
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----
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* The pod *pod-s2* is not scheduled unless there is a node with a pod that has the `security:s2` label. If there is no other pod with that label, the new pod remains in a pending state:
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+
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.Example output
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[source,terminal]
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----
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NAME READY STATUS RESTARTS AGE IP NODE
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pod-s2 0/1 Pending 0 32s <none>
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----
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