Unused CustomConfigMap revisions are not purged

[surendar-b]

Describe the bug
Configurator purges all the unused CustomConfigMap (CCM) revisions that were once referenced by a deployment or statefulset revision. Based on the revision history configured for a deployment/statefulset, Kubernetes automatically removes the unused deployment/statefulset revisions. If a CCM version was referenced in one of those unused deployment/statefulset revisions, then Configurator purges those unused CCMs periodically (once in every 15 mins). However, if a CCM has never been referenced in any of the deployment/statefulset revisions from the time of its creation, then Configurator does not purge those CCM revisions.

To Reproduce
Steps to reproduce the behavior:
1.Create a file named ConfigMap.yaml with the below contents and create a ConfigMap.

apiVersion: v1
kind: ConfigMap
metadata:
    name: demo-config
data:
  # property-like keys; each key maps to a simple value
  player_initial_lives: "3"
  ui_properties_file_name: "user-interface.properties"

  # file-like keys
  game.properties: |
    android.apk=free fire,bgmi
    computer=stambled guys    
  user-interface.properties: |
    color.good=purple
    color.bad=yellow
    allow.textmode=tru

$ kubectl apply -f ConfigMap.yaml

2.Edit the contents of the ConfigMap and save the ConfigMap. This will create a new CCM revision.

$ kubectl edit cm demo-config

3.List the CCM. It will show the 2 CCM versions.

$ kubectl get ccm 
NAME                     AGE
demo-config-ifoiu        28s
demo-config-sg1cl        3m30s

4.Wait for 15 minutes. After 15 minutes, the automatic purge functionality is invoked. But it doesn't delete the unused CCM versions.
5.List the CCM again. Note that there are 2 CCM revisions still.

$ kubectl get ccm 
NAME                     AGE
demo-config-ifoiu        14m
demo-config-sg1cl        17m

6.Create a new ConfigMap with the below contents.

$ vi ConfigMap-2.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: demo2-config
data:
  names: |
    paul
    peter

$ kubectl apply -f ConfigMap-2.yaml

7.Create a deployment using the new ConfigMap, and set the max revision to be maintained as 1 in ‘spec.revisionHistoryLimit’ level.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: demo-deployment
spec:
  replicas: 1
  revisionHistoryLimit: 1
  selector:
    matchLabels:
      app: service-nginx
  template:
    metadata:
      labels:
        app: service-nginx
    spec:
      containers:
        - name: nginx
          image: nginx:1.14
          ports:
            - containerPort: 80
          volumeMounts:
           - name: nginx
             mountPath: "/config"
             readOnly: true
      volumes:
      - name: nginx
        configMap:
          name: demo2-config

$ kubectl apply -f deployment.yaml

8.List the versions of ccm using

$kubectl get ccm 
NAME                     AGE
demo-config-ifoiu        16m
demo-config-sg1cl        19m
demo2-config-4c897       52s

$ kubectl get replicaset
NAME                                              DESIRED   CURRENT   READY   AGE
demo-deployment-57d8c679b7                        1         1         1       109s

9.Get new ConfigMap demo2-config as yaml. In annotation level deployment reference will be available

$ kubectl get cm demo2-config -o yaml
apiVersion: v1
data:
  names: |
    paul
    peter
kind: ConfigMap
metadata:
  annotations:
    currentCustomConfigMapVersion: 21iu3
    customConfigMap-name: demo2-config-21iu3
    deployments: demo-deployment
    updateMethod: ignoreWhenShared
  creationTimestamp: "2022-02-25T08:33:29Z"
  name: demo2-config
  namespace: default
  resourceVersion: "59171"
  uid: 371d2f53-8d8a-4c9b-999f-21482502655c

10.Edit the new ConfigMap using $ kubectl edit cm demo2-config
11.Check for replicaset

$ kubectl get replicaset
NAME                            DESIRED   CURRENT   READY   AGE
demo-deployment-57d8c679b7        0         0         0    4m19s
demo-deployment-5b6c7b5f57        1         1         1     40s

12.Wait for 15 mins. Check the older version is removed. The latest will be the second CCM and it will be retained. The first CCM version will be purged.

$ kubectl get replicaset demo-deployment-57d8c679b7  -o yaml

apiVersion: apps/v1
kind: ReplicaSet
metadata:
  annotations:
    deployment.kubernetes.io/desired-replicas: "1"
    deployment.kubernetes.io/max-replicas: "2"
    deployment.kubernetes.io/revision: "1"
  creationTimestamp: "2022-02-25T08:36:08Z"
  generation: 2
  labels:
    app: service-nginx
    pod-template-hash: 57d8c679b7
  name: demo-deployment-57d8c679b7
  namespace: default
  ownerReferences:
  - apiVersion: apps/v1
    blockOwnerDeletion: true
    controller: true
    kind: Deployment
    name: demo-deployment
    uid: 97589500-6569-4c61-a9c1-803769c0a864
  resourceVersion: "56630"
  uid: 52de3436-53a0-451c-aaf4-a36632ee1799
spec:
  replicas: 0
  selector:
    matchLabels:
      app: service-nginx
      pod-template-hash: 57d8c679b7
  template:
    metadata:
      annotations:
        ccm-demo2-config: 4c897
        config-sync-controller: configurator

$ kubectl get replicaset demo-deployment-5b6c7b5f57 -o yaml

apiVersion: apps/v1
kind: ReplicaSet
metadata:
  annotations:
    deployment.kubernetes.io/desired-replicas: "1"
    deployment.kubernetes.io/max-replicas: "2"
    deployment.kubernetes.io/revision: "2"
  creationTimestamp: "2022-02-25T08:39:47Z"
  generation: 1
  labels:
    app: service-nginx
    pod-template-hash: 5b6c7b5f57
  name: demo-deployment-5b6c7b5f57
  namespace: default
  ownerReferences:
  - apiVersion: apps/v1
    blockOwnerDeletion: true
    controller: true
    kind: Deployment
    name: demo-deployment
    uid: 97589500-6569-4c61-a9c1-803769c0a864
  resourceVersion: "56625"
  uid: 09796e75-e414-4342-a522-cec9c05b2f41
spec:
  replicas: 1
  selector:
    matchLabels:
      app: service-nginx
      pod-template-hash: 5b6c7b5f57
  template:
    metadata:
      annotations:
        ccm-demo2-config: we90z
        config-sync-controller: configurator

$  kubectl get ccm 
NAME                     AGE
demo-config-ifoiu        27m
demo-config-sg1cl        30m
demo2-config-4c897       11m
demo2-config-we90z       5m29s

$ kubectl edit cm demo2-config
configmap/demo2-config edited

$ kubectl get ccm 
NAME                     AGE
demo-config-ifoiu        29m
demo-config-sg1cl        32m
demo2-config-21iu3       33s
demo2-config-4c897       13m
demo2-config-we90z       7m8s
$ kubectl get replicaset
NAME                           DESIRED   CURRENT   READY   AGE
demo-deployment-5b6c7b5f57        0         0        0    7m35s
demo-deployment-8767c6b9b         1         1        1     60s

$ kubectl get replicaset demo-deployment-8767c6b9b -o yaml
apiVersion: apps/v1
kind: ReplicaSet
metadata:
  annotations:
    deployment.kubernetes.io/desired-replicas: "1"
    deployment.kubernetes.io/max-replicas: "2"
    deployment.kubernetes.io/revision: "3"
  creationTimestamp: "2022-02-25T08:46:22Z"
  generation: 1
  labels:
    app: service-nginx
    pod-template-hash: 8767c6b9b
  name: demo-deployment-8767c6b9b
  namespace: default
  ownerReferences:
  - apiVersion: apps/v1
    blockOwnerDeletion: true
    controller: true
    kind: Deployment
    name: demo-deployment
    uid: 97589500-6569-4c61-a9c1-803769c0a864
  resourceVersion: "59196"
  uid: 6d7052e6-34be-4363-8970-e13843d914df
spec:
  replicas: 1
  selector:
    matchLabels:
      app: service-nginx
      pod-template-hash: 8767c6b9b
  template:
    metadata:
      annotations:
        ccm-demo2-config: 21iu3
        config-sync-controller: configurator

$ kubectl get ccm 
NAME                     AGE
demo-config-ifoiu        41m
demo-config-sg1cl        44m
demo2-config-21iu3       12m
demo2-config-we90z       19m

Expected behavior
In step 5 : If a ConfigMap is not used in any deployment we must retain minimum 1 revision ie., latest revision

[gopaddle-io]

Please send pull requests to SODACODE-2022