Exec KRM functions with relative paths don't resolve when base kustomization is in use

[seh]

Description

Following up from #4117, while #4125 made it possible to use relative paths to specify the location of an exec KRM function, that resolution only works correctly when the kustomization containing the KRM function does not use any bases, and instead includes only resources—specifically, references to files below that kustomization root.

The following kustomization.yaml files demonstrate the possibilities:

No resources

Relative KRM function paths work as expected.

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

resources:

Only resources

Relative KRM function paths work as expected.

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

resources:
- deployment.yaml
- pdb.yaml

Only bases

Relative KRM function paths do not work as expected.

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

resources:
- ../../base

Bases and resources

Relative KRM function paths do not work as expected.

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

resources:
- ../../base
- hpa.yaml

Reproduction

Please consult the archive of a base kustomization and an overlay kustomization, where the overlay includes a KRM function.

kustomize-fn-defect.tar.gz

Preparation

mkdir -p /tmp/kustomize-demo
cd /tmp/kustomize-demo
tar zxf ~/Downloads/kustomize-fn-defect.tar.gz
kustomize build ./overlays/fn --enable-exec --enable-alpha-plugins

Expected Output

apiVersion: v1
data:
  color: red
kind: ConfigMap
metadata:
  name: settings

Actual Output

Error: couldn't execute function: fork/exec ./plugins/change-color: no such file or directory 

Environment

Kustomize Version

{Version:kustomize/v4.4.1 GitCommit:b2d65ddc98e09187a8e38adc27c30bab078c1dbf BuildDate:2021-11-11T23:27:14Z GoOs:darwin GoArch:amd64}

Platform

macOS 11.6 (Darwin Kernel Version 20.6.0)

Additional Context

If you change the "exec.path" field (embedded in the "config.kubernetes.io/function" annotation) in the krm-functions.yaml file to the absolute path to the change-color program (e.g. /tmp/kustomize-demo/overlays/fn/plugins/change-color), then kustomize build works as expected. Likewise, if you use a relative path to the change-color file and comment out the resource ../../base in the overlay kustomization.yaml file and instead include the ConfigMap content in a file within the overlay's directory (effectively changing the overlay into a base), then kustomize build works as expected.

[k8s-ci-robot]

@seh: This issue is currently awaiting triage.

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[seh]

I confirmed that if you specify a relative path to the exec KRM function file from the base kustomization root, it works. That is, in the example introduced here, if the "exec.path" field's value is ../overlays/fn/plugins/change-color, then kustomize finds the change-color file. Clearly it's using the base kustomization directory as its working directory. Instead, it should use the directory of the overlay kustomization that includes the function.

[seh]

See #4347 for a similar complaint.

[KnVerey]

/triage duplicate
/close

Thank you for the detailed report. Since this was opened slightly after #4347 (crazy timing!), let's continue there.

[k8s-ci-robot]

@KnVerey: Closing this issue.

In response to this:

/triage duplicate
/close

Thank you for the detailed report. Since this was opened slightly after #4347 (crazy timing!), let's continue there.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.