Add support for waiting on a StatefulSet. (#195)

Add support for waiting on a StatefulSet.

SUMMARY
This PR implements support for waiting on StatefulSet for readiness similar to how the other waiters currently work.
ISSUE TYPE

Feature Pull Request

ADDITIONAL INFORMATION
This was designed to (mostly) mimic the behaviour of the StatefulSetStatusViewer used by kubectl rollout status -w.

Reviewed-by: Abhijeet Kasurde <None>
Reviewed-by: Joshua K <None>
Reviewed-by: None <None>
Reviewed-by: Mike Graves <mgraves@redhat.com>
Reviewed-by: None <None>

molecule/default/tasks/waiter.yml

@@ -140,6 +140,111 @@
           - ds.result.status.currentNumberScheduled == ds.result.status.desiredNumberScheduled
           - updated_ds_pods.resources[0].spec.containers[0].image.endswith(":3")
 
+    - name: Add a statefulset
+      k8s:
+        definition:
+          apiVersion: apps/v1
+          kind: StatefulSet
+          metadata:
+            name: wait-statefulset
+            namespace: "{{ wait_namespace }}"
+          spec:
+            selector:
+              matchLabels:
+                app: "{{ k8s_pod_name }}"
+            template: "{{ k8s_pod_template }}"
+        wait: yes
+        wait_sleep: 5
+        wait_timeout: 180
+      vars:
+        k8s_pod_name: wait-sts
+        k8s_pod_image: gcr.io/kuar-demo/kuard-amd64:1
+        k8s_pod_command:
+          - sleep
+          - "600"
+      register: sts
+
+    - name: Check that statefulset wait worked
+      assert:
+        that:
+          - sts.result.spec.replicas == sts.result.status.readyReplicas
+
+    - name: Update a statefulset in check_mode
+      k8s:
+        definition:
+          apiVersion: apps/v1
+          kind: StatefulSet
+          metadata:
+            name: wait-statefulset
+            namespace: "{{ wait_namespace }}"
+          spec:
+            selector:
+              matchLabels:
+                app: "{{ k8s_pod_name }}"
+            updateStrategy:
+              type: RollingUpdate
+            template: "{{ k8s_pod_template }}"
+        wait: yes
+        wait_sleep: 3
+        wait_timeout: 180
+      vars:
+        k8s_pod_name: wait-sts
+        k8s_pod_image: gcr.io/kuar-demo/kuard-amd64:2
+        k8s_pod_command:
+          - sleep
+          - "600"
+      register: update_sts_check_mode
+      check_mode: yes
+
+    - name: Check that check_mode result contains the changes
+      assert:
+        that:
+          - update_sts_check_mode is changed
+          - "update_sts_check_mode.result.spec.template.spec.containers[0].image == 'gcr.io/kuar-demo/kuard-amd64:2'"
+
+    - name: Update a statefulset
+      k8s:
+        definition:
+          apiVersion: apps/v1
+          kind: StatefulSet
+          metadata:
+            name: wait-statefulset
+            namespace: "{{ wait_namespace }}"
+          spec:
+            selector:
+              matchLabels:
+                app: "{{ k8s_pod_name }}"
+            updateStrategy:
+              type: RollingUpdate
+            template: "{{ k8s_pod_template }}"
+        wait: yes
+        wait_sleep: 3
+        wait_timeout: 180
+      vars:
+        k8s_pod_name: wait-sts
+        k8s_pod_image: gcr.io/kuar-demo/kuard-amd64:3
+        k8s_pod_command:
+          - sleep
+          - "600"
+      register: sts
+
+    - name: Get updated pods
+      k8s_info:
+        api_version: v1
+        kind: Pod
+        namespace: "{{ wait_namespace }}"
+        label_selectors:
+          - app=wait-sts
+        field_selectors:
+          - status.phase=Running
+      register: updated_sts_pods
+
+    - name: Check that statefulset wait worked
+      assert:
+        that:
+          - sts.result.spec.replicas == sts.result.status.readyReplicas
+          - updated_sts_pods.resources[0].spec.containers[0].image.endswith(":3")
+
     - name: Add a crashing pod
       k8s:
         definition: