CODEWITHSUNDEEP
kubernetesyaml
learner
learner

Reputation: 2840

Correct YAML format for kubernetes migration

I have a YAML file as like below which I have exported from an existing cluster:

apiVersion: v1
items:
- apiVersion: v1
  kind: ServiceAccount
  metadata:
    creationTimestamp: 2019-03-20T23:17:42Z
    name: default
    namespace: dev4
    resourceVersion: "80999"
    selfLink: /api/v1/namespaces/dev4/serviceaccounts/default
    uid: 5c6e0d09-4b66-11e9-b4e3-0a779a87bb40
  secrets:
  - name: default-token-tl4dd
- apiVersion: v1
  kind: ServiceAccount
  metadata:
    annotations:
      kubectl.kubernetes.io/last-applied-configuration: |
        {"apiVersion":"v1","kind":"ServiceAccount","metadata":{"annotations":{},"name":"pod-labeler","namespace":"dev4"}}
    creationTimestamp: 2020-04-21T05:46:25Z
    name: pod-labeler
    namespace: dev4
    resourceVersion: "113455688"
    selfLink: /api/v1/namespaces/dev4/serviceaccounts/pod-labeler
    uid: 702dadda-8393-11ea-abd9-0a768ca51346
  secrets:
  - name: pod-labeler-token-6vgp7
kind: List
metadata:
  resourceVersion: ""
  selfLink: ""

If I do the above YAML and apply to a new cluster, I get an error, which is out of the scope of this question.

In summary, I have to get rid of the below attributes:

uid:
selfLink:
resourceVersion:
creationTimestamp:

So I got a sed command like below which does the trick

sed -i '/uid: \|selfLink: \|resourceVersion: \|creationTimestamp: /d' dev4-serviceaccounts.yaml

The final YAML file is like below:

apiVersion: v1
items:
- apiVersion: v1
  kind: ServiceAccount
  metadata:
    name: default
    namespace: dev4
  secrets:
  - name: default-token-tl4dd
- apiVersion: v1
  kind: ServiceAccount
  metadata:
    annotations:
      kubectl.kubernetes.io/last-applied-configuration: |
        {"apiVersion":"v1","kind":"ServiceAccount","metadata":{"annotations":{},"name":"pod-labeler","namespace":"dev4"}}
    name: pod-labeler
    namespace: dev4
  secrets:
  - name: pod-labeler-token-6vgp7
kind: List
metadata:

My question is, is it the correct YAML file as it erases the empty tag and values for metadata...(AT the very much last of the YAML file)

I can create objects - serviceaccounts in this instance, but I just want to ensure if I am doing is correct or any other better approach.

Upvotes: 1

Views: 369

Answers (1)

Matt
Matt

Reputation: 8142

In this specific case this is correct but you need to be carefull with it since there is no consistent way to do this for all types of resources.

Historically kubectl had --export flag that was generating yamls ready to apply, but it got depricated because of many bugs. Check out the issue on k8s github repo for more details.

There is also another way to export the resources if you used kubectl apply to create it.

kubectl apply view-last-applied <api-resource> <name> -oyaml
e.g.:
kubectl apply view-last-applied serviceaccount pod-labeler -oyaml

But remember that this won't work for resources created with helm or other tools.

The best thing you could do is to always keep all your source files in git or similar, so you don't ever need to export it.

Upvotes: 1

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