Leader election conflict with csi-resizer bug fix

[torredil]

Issue #, if available:

• Closes Leader election conflict with csi-resizer #13
• Leader election issues for csi-resizer and volumemodifier kubernetes-sigs/aws-ebs-csi-driver#1759

Description of changes:

This PR introduces modifications to ensure that the volumemodifier container sidecar initializes the controller service only if it is in the same pod as the csi-resizer leader. This determination is made by monitoring the leases object. If the controller service is running but the pod is not the leader, the controller service will be stopped.

Pod name will be supplied via downward API:

- name: POD_NAME
           valueFrom:
             fieldRef:
               fieldPath: metadata.name

Additionally, the following clusterrole will be necessary:

kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: ebs-external-modifier-role
  labels:
    {{- include "aws-ebs-csi-driver.labels" . | nindent 4 }}
rules:
  - apiGroups: [ "coordination.k8s.io" ]
    resources: [ "leases" ]
    verbs: [ "get", "list", "watch", "update", "patch" ]
  {{- with .Values.sidecars.attacher.additionalClusterRoleRules }}
    {{- . | toYaml | nindent 2 }}
  {{- end }}

Testing:

$ kubectl get leases -n kube-system
NAME                                       HOLDER                                                                  AGE
external-resizer-ebs-csi-aws-com           ebs-csi-controller-79cb7bc657-ch4zd                                     20m

$ kubectl logs  ebs-csi-controller-79cb7bc657-ch4zd -n kube-system -c volumemodifier   
I1003 14:37:53.657602       1 main.go:74] Version : v0.1.1
I1003 14:37:53.665513       1 common.go:111] Probing CSI driver for readiness
I1003 14:37:53.677936       1 main.go:116] CSI driver name: "ebs.csi.aws.com"
I1003 14:37:54.142566       1 main.go:179] "Starting controller" podName="ebs-csi-controller-79cb7bc657-ch4zd" currentLeader="ebs-csi-controller-79cb7bc657-ch4zd"
I1003 14:37:54.142627       1 controller.go:95] "Starting external modifier" name="ebs.csi.aws.com"

$ kubectl delete leases external-resizer-ebs-csi-aws-com -n kube-system

$ kubectl get leases -n kube-system
 external-resizer-ebs-csi-aws-com           ebs-csi-controller-79cb7bc657-lr6rw                                     1s

$ kubectl logs  ebs-csi-controller-79cb7bc657-lr6rw -n kube-system -c volumemodifier   
I1003 14:40:51.085418       1 main.go:74] Version : v0.1.1
I1003 14:40:51.087163       1 common.go:111] Probing CSI driver for readiness
I1003 14:40:51.090251       1 main.go:116] CSI driver name: "ebs.csi.aws.com"
I1003 15:02:30.527414       1 main.go:179] "Starting controller" podName="ebs-csi-controller-79cb7bc657-lr6rw" currentLeader="ebs-csi-controller-79cb7bc657-lr6rw"
I1003 15:02:30.527479       1 controller.go:95] "Starting external modifier" name="ebs.csi.aws.com"

$ kubectl logs ebs-csi-controller-79cb7bc657-ch4zd -n kube-system -c volumemodifier  
I1003 15:02:31.443715       1 main.go:74] Version : v0.1.1
I1003 15:02:31.450041       1 common.go:111] Probing CSI driver for readiness
I1003 15:02:31.469327       1 main.go:116] CSI driver name: "ebs.csi.aws.com"

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[torredil]

cc: @ConnorJC3 @AndrewSirenko

[ConnorJC3]

lgtm

[ConnorJC3]

Also, can we put "Closes" in the PR description in front of the issues in the Issue #, if available: section (so this PR will auto-link to them)?

[ConnorJC3]

lgtm

[AndrewSirenko]

/lgtm

[AndrewSirenko]

/approve