Fix waiting for daemonset when desired number of pods is 0 (#756) (#762)

This is a backport of PR #756 as merged into main (b07fbd6).
Fixes #755
SUMMARY
Because we don't have any node with non_exisiting_label (see code below) desired number of Pods will be 0. Kubernetes won't create .status.updatedNumberScheduled field (at least on version v1.27), because we still are not going to create any Pods. So that if .status.updatedNumberScheduled doesn't exist we should assume that number is 0
Code to reproduce:
- name: Create daemonset
  kubernetes.core.k8s:
    state: present
    wait: true
    definition:
      apiVersion: apps/v1
      kind: DaemonSet
      metadata:
        name: my-daemonset
        namespace: default
      spec:
        selector:
          matchLabels:
            app: my-app
        template:
          metadata:
            labels:
              app: my-app
          spec:
            containers:
              - name: my-container
                image: nginx
            nodeSelector:
              non_exisiting_label: 1
ISSUE TYPE

Bugfix Pull Request

COMPONENT NAME
kubernetes.core.plugins.module_utils.k8s.waiter
ADDITIONAL INFORMATION



TASK [Create daemonset] **********************************************************************************************************************************
changed: [controlplane] => {"changed": true, "duration": 5, "method": "create", "result": {"apiVersion": "apps/v1", "kind": "DaemonSet", "metadata": {"annotations": {"deprecated.daemonset.template.generation": "1"}, "creationTimestamp": "2024-06-28T08:23:41Z", "generation": 1, "managedFields": [{"apiVersion": "apps/v1", "fieldsType": "FieldsV1", "fieldsV1": {"f:metadata": {"f:annotations": {".": {}, "f:deprecated.daemonset.template.generation": {}}}, "f:spec": {"f:revisionHistoryLimit": {}, "f:selector": {}, "f:template": {"f:metadata": {"f:labels": {".": {}, "f:app": {}}}, "f:spec": {"f:containers": {"k:{\"name\":\"my-container\"}": {".": {}, "f:image": {}, "f:imagePullPolicy": {}, "f:name": {}, "f:resources": {}, "f:terminationMessagePath": {}, "f:terminationMessagePolicy": {}}}, "f:dnsPolicy": {}, "f:nodeSelector": {}, "f:restartPolicy": {}, "f:schedulerName": {}, "f:securityContext": {}, "f:terminationGracePeriodSeconds": {}}}, "f:updateStrategy": {"f:rollingUpdate": {".": {}, "f:maxSurge": {}, "f:maxUnavailable": {}}, "f:type": {}}}}, "manager": "OpenAPI-Generator", "operation": "Update", "time": "2024-06-28T08:23:41Z"}, {"apiVersion": "apps/v1", "fieldsType": "FieldsV1", "fieldsV1": {"f:status": {"f:observedGeneration": {}}}, "manager": "kube-controller-manager", "operation": "Update", "subresource": "status", "time": "2024-06-28T08:23:41Z"}], "name": "my-daemonset", "namespace": "default", "resourceVersion": "1088421", "uid": "faafdbf7-4388-4cec-88d5-84657966312d"}, "spec": {"revisionHistoryLimit": 10, "selector": {"matchLabels": {"app": "my-app"}}, "template": {"metadata": {"creationTimestamp": null, "labels": {"app": "my-app"}}, "spec": {"containers": [{"image": "nginx", "imagePullPolicy": "Always", "name": "my-container", "resources": {}, "terminationMessagePath": "/dev/termination-log", "terminationMessagePolicy": "File"}], "dnsPolicy": "ClusterFirst", "nodeSelector": {"non_exisiting_label": "1"}, "restartPolicy": "Always", "schedulerName": "default-scheduler", "securityContext": {}, "terminationGracePeriodSeconds": 30}}, "updateStrategy": {"rollingUpdate": {"maxSurge": 0, "maxUnavailable": 1}, "type": "RollingUpdate"}}, "status": {"currentNumberScheduled": 0, "desiredNumberScheduled": 0, "numberMisscheduled": 0, "numberReady": 0, "observedGeneration": 1}}}

~$ kubectl get ds
NAME           DESIRED   CURRENT   READY   UP-TO-DATE   AVAILABLE   NODE SELECTOR           AGE
my-daemonset   0         0         0       0            0           non_exisiting_label=1   30s

Reviewed-by: Mike Graves <mgraves@redhat.com>

changelogs/fragments/756-fix-daemonset-waiting.yaml

@@ -0,0 +1,2 @@
+bugfixes:
+  - waiter - Fix waiting for daemonset when desired number of pods is 0. (https://github.com/ansible-collections/kubernetes.core/pull/756).

plugins/module_utils/k8s/waiter.py

@@ -51,7 +51,7 @@ def daemonset_ready(daemonset: ResourceInstance) -> bool:
     return bool(
         daemonset.status
         and daemonset.status.desiredNumberScheduled is not None
-        and daemonset.status.updatedNumberScheduled
+        and (daemonset.status.updatedNumberScheduled or 0)
         == daemonset.status.desiredNumberScheduled
         and daemonset.status.numberReady == daemonset.status.desiredNumberScheduled
         and daemonset.status.observedGeneration == daemonset.metadata.generation

tests/integration/targets/k8s_waiter/defaults/main.yml

@@ -5,6 +5,7 @@ k8s_pod_metadata:
 
 k8s_pod_spec:
   serviceAccount: "{{ k8s_pod_service_account }}"
+  nodeSelector: "{{ k8s_pod_node_selector }}"
   containers:
     - image: "{{ k8s_pod_image }}"
       imagePullPolicy: Always
@@ -33,6 +34,8 @@ k8s_pod_ports: []
 
 k8s_pod_env: []
 
+k8s_pod_node_selector: {}
+
 k8s_pod_template:
   metadata: "{{ k8s_pod_metadata }}"
   spec: "{{ k8s_pod_spec }}"

tests/integration/targets/k8s_waiter/tasks/main.yml

@@ -127,6 +127,48 @@
           - ds.result.status.currentNumberScheduled == ds.result.status.desiredNumberScheduled
           - updated_ds_pods.resources[0].spec.containers[0].image.endswith(":3")
 
+    - name: Create daemonset with nodeSelector and not existing label
+      k8s:
+        definition:
+          apiVersion: apps/v1
+          kind: DaemonSet
+          metadata:
+            name: wait-daemonset-not-existing-label
+            namespace: "{{ wait_namespace }}"
+          spec:
+            selector:
+              matchLabels:
+                app: "{{ k8s_pod_name }}"
+            template: "{{ k8s_pod_template }}"
+        wait: yes
+        wait_sleep: 5
+        wait_timeout: "{{ k8s_wait_timeout | default(omit) }}"
+      vars:
+        k8s_pod_name: wait-daemonset-not-existing-label
+        k8s_pod_image: gcr.io/kuar-demo/kuard-amd64:1
+        k8s_pod_command:
+          - sleep
+          - "600"
+        k8s_pod_node_selector:
+          nonExisitingLabel: test-not-exiting-label
+      register: ds_not_existing_label
+
+    - name: Get updated pods
+      k8s_info:
+        api_version: v1
+        kind: Pod
+        namespace: "{{ wait_namespace }}"
+        label_selectors:
+          - app=wait-daemonset-not-existing-label
+      register: updated_ds_pods_not_existing_label
+
+    - name: Check that daemonset wait worked (when desired number is 0)
+      assert:
+        that:
+          - ds_not_existing_label.result.status.currentNumberScheduled == ds_not_existing_label.result.status.desiredNumberScheduled
+          - ds_not_existing_label.result.status.desiredNumberScheduled == 0
+          - updated_ds_pods_not_existing_label.resources | length == 0
+
     - name: Add a statefulset
       k8s:
         definition: