Fix waiting on StatefulSet scale down (#391)

Fix waiting on StatefulSet scale down

SUMMARY

When scaling a StatefulSet down to 0 replicas the wait will fail
because some properties of the status (readyReplicas, updatedReplicas)
will not exist. These are probably defined as omitempty in the API and
since the value is zero are not present in the response.

Fixes #203
ISSUE TYPE


Bugfix Pull Request

COMPONENT NAME

k8s_scale
ADDITIONAL INFORMATION

Reviewed-by: Gonéri Le Bouder <goneri@lebouder.net>

changelogs/fragments/391-fix-statefulset-wait.yaml

@@ -0,0 +1,2 @@
+bugfixes:
+  - k8s_scale - fix waiting on statefulset when scaled down to 0 replicas (https://github.com/ansible-collections/kubernetes.core/issues/203).

plugins/module_utils/common.py

@@ -633,6 +633,10 @@ class K8sAnsibleMixin(object):
             )
 
         def _statefulset_ready(statefulset):
+            # These may be None
+            updated_replicas = statefulset.status.updatedReplicas or 0
+            ready_replicas = statefulset.status.readyReplicas or 0
+
             return (
                 statefulset.status
                 and statefulset.spec.updateStrategy.type == "RollingUpdate"
@@ -640,8 +644,8 @@ class K8sAnsibleMixin(object):
                 == (statefulset.metadata.generation or 0)
                 and statefulset.status.updateRevision
                 == statefulset.status.currentRevision
-                and statefulset.status.updatedReplicas == statefulset.spec.replicas
-                and statefulset.status.readyReplicas == statefulset.spec.replicas
+                and updated_replicas == statefulset.spec.replicas
+                and ready_replicas == statefulset.spec.replicas
                 and statefulset.status.replicas == statefulset.spec.replicas
             )
 

tests/integration/targets/k8s_scale/tasks/main.yml

@@ -341,6 +341,54 @@
           - scale_out.changed
           - scale_out.results | map(attribute='result.status.replicas') | list | unique == [2]
 
+    - name: Create a StatefulSet
+      kubernetes.core.k8s:
+        wait: yes
+        wait_timeout: "{{ k8s_wait_timeout | default(omit) }}"
+        definition:
+          apiVersion: apps/v1
+          kind: StatefulSet
+          metadata:
+            namespace: "{{ scale_namespace }}"
+            name: scale-set
+          spec:
+            replicas: 2
+            selector:
+              matchLabels:
+                app: foo
+            template:
+              metadata:
+                labels:
+                  app: foo
+              spec:
+                terminationGracePeriodSeconds: 10
+                containers:
+                  - image: busybox
+                    name: busybox
+                    command:
+                      - sleep
+                      - "600"
+      register: output
+
+    - assert:
+        that:
+          - output.result.status.replicas == 2
+
+    - name: Wait for StatefulSet to scale down to 0
+      kubernetes.core.k8s_scale:
+        kind: StatefulSet
+        api_version: apps/v1
+        name: scale-set
+        namespace: "{{ scale_namespace }}"
+        replicas: 0
+        wait: yes
+        wait_timeout: "{{ k8s_wait_timeout | default(omit) }}"
+      register: output
+
+    - assert:
+        that:
+          - output.result.status.replicas == 0
+
   always:
     - name: Remove namespace
       k8s: