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PersistentVolumeClaim rebase

PersistentVolumeClaim rebase ¶

Here is an example on how to use custom rebaseRules to “prefer” server chosen value for several annotations added by PVC controller (in other words, cluster owned fields), instead of removing them based on given configuration.

Let’s deploy via kapp deploy -a test -f config.yml -c with following configuration config.yml:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mysqlclaim
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 5Gi

Without additional rebase rules following diff will be presented upon next deploy, stating that several annotations will be removed (since they were not present in the initial configuration):

$ kapp deploy -a test -f config.yml -c

Target cluster 'https://x.x.x.x' (nodes: gke-dk-jan-9-default-pool-a218b1c9-55sl, 3+)

--- update persistentvolumeclaim/mysqlclaim (v1) namespace: default
  ...
  2,  2   metadata:
  3     -   annotations:
  4     -     pv.kubernetes.io/bind-completed: "yes"
  5     -     pv.kubernetes.io/bound-by-controller: "yes"
  6     -     volume.beta.kubernetes.io/storage-provisioner: kubernetes.io/gce-pd
  7,  3     creationTimestamp: "2020-03-08T22:17:29Z"
  8,  4     finalizers:
  ...
 24, 20     storageClassName: standard
 25     -   volumeMode: Filesystem
 26, 21     volumeName: pvc-1be63b2b-20de-429c-863a-9e7eb062f5d3
 27, 22   status:

Changes

Namespace  Name        Kind                   Conds.  Age  Op      Wait to    Rs  Ri
default    mysqlclaim  PersistentVolumeClaim  -       43s  update  reconcile  ok  -

Op:      0 create, 0 delete, 1 update, 0 noop, 0 exists
Wait to: 1 reconcile, 0 delete, 0 noop

Continue? [yN]:

To let kapp know that these annotations should be copied from the live resource copy, we can augment deploys with following configuration kapp-config.yml:

---
apiVersion: kapp.k14s.io/v1alpha1
kind: Config

rebaseRules:
- path: [metadata, annotations, pv.kubernetes.io/bind-completed]
  type: copy
  sources: [new, existing]
  resourceMatchers: &pvcs
  - apiVersionKindMatcher:
      apiVersion: v1
      kind: PersistentVolumeClaim

- path: [metadata, annotations, pv.kubernetes.io/bound-by-controller]
  type: copy
  sources: [new, existing]
  resourceMatchers: *pvcs

- path: [metadata, annotations, volume.beta.kubernetes.io/storage-provisioner]
  type: copy
  sources: [new, existing]
  resourceMatchers: *pvcs

- path: [spec, volumeMode]
  type: copy
  sources: [new, existing]
  resourceMatchers: *pvcs

$ kapp deploy -a test -f config.yml -f kapp-config.yml -c

Target cluster 'https://x.x.x.x' (nodes: gke-dk-jan-9-default-pool-a218b1c9-55sl, 3+)

Changes

Namespace  Name  Kind  Conds.  Age  Op  Wait to  Rs  Ri

Op:      0 create, 0 delete, 0 update, 0 noop, 0 exists
Wait to: 0 reconcile, 0 delete, 0 noop

Succeeded

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