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Add node affinity support (zalando#1166)
* Adding nodeaffinity support alongside node_readiness_label * add documentation for node affinity * add node affinity e2e test * add unit test for node affinity Co-authored-by: Steffen Pøhner Henriksen <[email protected]> Co-authored-by: Adrian Astley <[email protected]>
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‎charts/postgres-operator/crds/postgresqls.yaml

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@@ -396,6 +396,97 @@ spec:
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type: string
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caSecretName:
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type: string
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nodeAffinity:
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type: object
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properties:
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preferredDuringSchedulingIgnoredDuringExecution:
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type: array
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items:
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type: object
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required:
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- weight
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- preference
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properties:
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preference:
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type: object
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properties:
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matchExpressions:
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type: array
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items:
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type: object
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required:
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- key
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- operator
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properties:
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key:
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type: string
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operator:
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type: string
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values:
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type: array
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items:
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type: string
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matchFields:
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type: array
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items:
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type: object
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required:
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- key
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- operator
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properties:
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key:
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type: string
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operator:
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type: string
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values:
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type: array
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items:
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type: string
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weight:
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format: int32
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type: integer
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requiredDuringSchedulingIgnoredDuringExecution:
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type: object
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required:
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- nodeSelectorTerms
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properties:
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nodeSelectorTerms:
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type: array
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items:
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type: object
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properties:
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matchExpressions:
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type: array
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items:
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type: object
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required:
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- key
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- operator
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properties:
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key:
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type: string
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operator:
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type: string
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values:
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type: array
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items:
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type: string
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matchFields:
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type: array
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items:
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type: object
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required:
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- key
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- operator
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properties:
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key:
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type: string
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operator:
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type: string
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values:
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type: array
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items:
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type: string
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tolerations:
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type: array
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items:

‎docs/user.md

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@@ -517,7 +517,7 @@ manifest the operator will raise the limits to the configured minimum values.
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If no resources are defined in the manifest they will be obtained from the
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configured [default requests](reference/operator_parameters.md#kubernetes-resource-requests).
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## Use taints and tolerations for dedicated PostgreSQL nodes
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## Use taints, tolerations and node affinity for dedicated PostgreSQL nodes
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To ensure Postgres pods are running on nodes without any other application pods,
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you can use [taints and tolerations](https://kubernetes.io/docs/concepts/configuration/taint-and-toleration/)
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effect: NoSchedule
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```
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If you need the pods to be scheduled on specific nodes you may use [node affinity](https://kubernetes.io/docs/tasks/configure-pod-container/assign-pods-nodes-using-node-affinity/)
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to specify a set of label(s), of which a prospective host node must have at least one. This could be used to
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place nodes with certain hardware capabilities (e.g. SSD drives) in certain environments or network segments,
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e.g. for PCI compliance.
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```yaml
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apiVersion: "acid.zalan.do/v1"
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kind: postgresql
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metadata:
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name: acid-minimal-cluster
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spec:
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teamId: "ACID"
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nodeAffinity:
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requiredDuringSchedulingIgnoredDuringExecution:
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nodeSelectorTerms:
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- matchExpressions:
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- key: environment
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operator: In
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values:
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- pci
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```
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## How to clone an existing PostgreSQL cluster
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You can spin up a new cluster as a clone of the existing one, using a `clone`

‎e2e/tests/test_e2e.py

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@@ -929,6 +929,112 @@ def test_zzz_taint_based_eviction(self):
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new_master_node = nm[0]
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self.assert_distributed_pods(new_master_node, new_replica_nodes, cluster_label)
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@timeout_decorator.timeout(TEST_TIMEOUT_SEC)
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def test_node_affinity(self):
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'''
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Add label to a node and update postgres cluster spec to deploy only on a node with that label
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'''
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k8s = self.k8s
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cluster_label = 'application=spilo,cluster-name=acid-minimal-cluster'
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# verify we are in good state from potential previous tests
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self.eventuallyEqual(lambda: k8s.count_running_pods(), 2, "No 2 pods running")
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self.eventuallyEqual(lambda: len(k8s.get_patroni_running_members("acid-minimal-cluster-0")), 2, "Postgres status did not enter running")
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self.eventuallyEqual(lambda: self.k8s.get_operator_state(), {"0": "idle"}, "Operator does not get in sync")
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# get nodes of master and replica(s)
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master_node, replica_nodes = k8s.get_pg_nodes(cluster_label)
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self.assertNotEqual(master_node, [])
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self.assertNotEqual(replica_nodes, [])
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# label node with environment=postgres
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node_label_body = {
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"metadata": {
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"labels": {
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"node-affinity-test": "postgres"
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}
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}
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}
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try:
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# patch current master node with the label
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print('patching master node: {}'.format(master_node))
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k8s.api.core_v1.patch_node(master_node, node_label_body)
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# add node affinity to cluster
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patch_node_affinity_config = {
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"spec": {
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"nodeAffinity" : {
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"requiredDuringSchedulingIgnoredDuringExecution": {
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"nodeSelectorTerms": [
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{
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"matchExpressions": [
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{
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"key": "node-affinity-test",
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"operator": "In",
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"values": [
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"postgres"
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]
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}
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]
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}
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]
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}
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}
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}
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}
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k8s.api.custom_objects_api.patch_namespaced_custom_object(
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group="acid.zalan.do",
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version="v1",
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namespace="default",
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plural="postgresqls",
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name="acid-minimal-cluster",
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body=patch_node_affinity_config)
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self.eventuallyEqual(lambda: self.k8s.get_operator_state(), {"0": "idle"}, "Operator does not get in sync")
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# node affinity change should cause replica to relocate from replica node to master node due to node affinity requirement
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k8s.wait_for_pod_failover(master_node, 'spilo-role=replica,' + cluster_label)
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k8s.wait_for_pod_start('spilo-role=replica,' + cluster_label)
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podsList = k8s.api.core_v1.list_namespaced_pod('default', label_selector=cluster_label)
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for pod in podsList.items:
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if pod.metadata.labels.get('spilo-role') == 'replica':
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self.assertEqual(master_node, pod.spec.node_name,
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"Sanity check: expected replica to relocate to master node {}, but found on {}".format(master_node, pod.spec.node_name))
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# check that pod has correct node affinity
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key = pod.spec.affinity.node_affinity.required_during_scheduling_ignored_during_execution.node_selector_terms[0].match_expressions[0].key
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value = pod.spec.affinity.node_affinity.required_during_scheduling_ignored_during_execution.node_selector_terms[0].match_expressions[0].values[0]
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self.assertEqual("node-affinity-test", key,
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"Sanity check: expect node selector key to be equal to 'node-affinity-test' but got {}".format(key))
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self.assertEqual("postgres", value,
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"Sanity check: expect node selector value to be equal to 'postgres' but got {}".format(value))
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patch_node_remove_affinity_config = {
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"spec": {
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"nodeAffinity" : None
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}
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}
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k8s.api.custom_objects_api.patch_namespaced_custom_object(
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group="acid.zalan.do",
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version="v1",
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namespace="default",
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plural="postgresqls",
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name="acid-minimal-cluster",
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body=patch_node_remove_affinity_config)
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self.eventuallyEqual(lambda: self.k8s.get_operator_state(), {"0": "idle"}, "Operator does not get in sync")
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# remove node affinity to move replica away from master node
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nm, new_replica_nodes = k8s.get_cluster_nodes()
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new_master_node = nm[0]
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self.assert_distributed_pods(new_master_node, new_replica_nodes, cluster_label)
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except timeout_decorator.TimeoutError:
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print('Operator log: {}'.format(k8s.get_operator_log()))
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raise
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@timeout_decorator.timeout(TEST_TIMEOUT_SEC)
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def test_zzzz_cluster_deletion(self):
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'''

‎manifests/complete-postgres-manifest.yaml

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# When TLS is enabled, also set spiloFSGroup parameter above to the relevant value.
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# if unknown, set it to 103 which is the usual value in the default spilo images.
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# In Openshift, there is no need to set spiloFSGroup/spilo_fsgroup.
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# Add node affinity support by allowing postgres pods to schedule only on nodes that
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# have label: "postgres-operator:enabled" set.
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# nodeAffinity:
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# requiredDuringSchedulingIgnoredDuringExecution:
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# nodeSelectorTerms:
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# - matchExpressions:
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# - key: postgres-operator
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# operator: In
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# values:
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# - enabled

‎manifests/postgresql.crd.yaml

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type: string
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caSecretName:
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type: string
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nodeAffinity:
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type: object
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properties:
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preferredDuringSchedulingIgnoredDuringExecution:
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type: array
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items:
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type: object
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required:
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- weight
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- preference
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properties:
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preference:
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type: object
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properties:
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matchExpressions:
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type: array
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items:
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type: object
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required:
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- key
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- operator
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properties:
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key:
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type: string
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operator:
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type: string
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values:
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type: array
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items:
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type: string
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matchFields:
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type: array
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items:
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type: object
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required:
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- key
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- operator
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properties:
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key:
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type: string
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operator:
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type: string
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values:
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type: array
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items:
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type: string
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weight:
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format: int32
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type: integer
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requiredDuringSchedulingIgnoredDuringExecution:
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type: object
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required:
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- nodeSelectorTerms
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properties:
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nodeSelectorTerms:
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type: array
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items:
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type: object
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properties:
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matchExpressions:
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type: array
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items:
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type: object
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required:
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- key
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- operator
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properties:
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key:
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type: string
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operator:
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type: string
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values:
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type: array
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items:
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type: string
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matchFields:
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type: array
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items:
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type: object
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required:
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- key
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- operator
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properties:
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key:
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type: string
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operator:
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type: string
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values:
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type: array
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items:
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type: string
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tolerations:
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type: array
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items:

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