Value from YAML fragment that is embedded as multiline scalar value

[christian-2]

I would like to exact a value from a ConfigMap that contains a YAML fragment that is embedded inside another YAML fragment as multlline scalar value. ConfigMaps like this constitute a fairly common pattern with Kubernetes.

The relevant part of my ConfigMap looks as follows:

apiVersion: v1
kind: ConfigMap
metadata:
  name: config
data:
  config: |
    test:
      url: https://github.com

The relevant part of my kustomization.yaml looks as follows:

vars:
- name: URL
  objref:
    kind: ConfigMap
    name: config
    apiVersion: v1
  fieldref:
    fieldpath: data.config.test.url

This does not work for comprehensible reasons: It assumes that there is a single YAML fragment, not one that embeds another one as multiline string.

I guess what would be needed is support for fieldpaths such as yaml(data.config).test.url, conceptually speaking. Or am I missing something? Is there support for accessing such embedded values for the purpose of setting environment variables in kustomization.yaml and if so, how could this be accomplished in my concrete example.

[christian-2]

I have meanwhile taken note of the recommendation that one should migrate from vars to replacement. But even then the same question remains now with respect to source.fieldPath.

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[koba1t]

Hi @christian-2

I think your use case is covered in my enhancement proposal.
#4558

Could you check the above proposal and decide whether that is enough for your want?

[annasong20]

As @koba1t suggests, this feature seems to duplicate #3787 #4517

/kind feature
/triage duplicate

[christian-2]

@koba1t Sorry for the late response @annasong20 @koba1t Yes, I can see now that the same use case has come up before, and I'd like to support these earlier efforts. Hence I would not insist on my sketched solution (with yaml() in fieldpaths over an ability to specify merge behavior, say.) Please advise if you want me to close this issue.

[annasong20]

Defer to @koba1t

[koba1t]

Hi @christian-2
I prefer to close this issue, and please join the discussion for that Proposal if you want.

I want to get a lot of feedback for this function!
I am happy to get your comments!