"/workspace" in the path of "output resource"

[vincent-pli]

I'm confuse, maybe missing something.
I have a task with output resource and targetpath, like this:

apiVersion: tekton.dev/v1alpha1
kind: Task
metadata:
  name: build-push
spec:
  outputs:
    resources:
    - name: builtImage
      type: image
      targetPath: /pengli/builtImage
  steps:
  - name: build-and-push
    image: docker
    args: ["touch", "$(outputs.resources.builtImage.path)/README.md"]

Simple, but get error: touch: /workspace/pengli/builtImage/README.md: No such file or directory
I checked the env, actually /pengli/builtImage/ is created.

I have no idea if it's a mistake, but I think /workspace/* should be the correct one, since containers in pod shared file system only with several mount points, /workspace/* is one of them. we expect sharing in containers.

Expected Behavior

Taskrun sucess

Actual Behavior

Failed

Steps to Reproduce the Problem

Additional Info

[chmouel]

/label bug

I think you only need a workingDir: /workspace in the container spec ?

[vdemeester]

/kind question
I am not actually sure if it's a bug, I would have thought if you specify the targetPath it shouldn't be prepended by /workspace.

/cc @dlorenc @bobcatfish

[vincent-pli]

@vdemeester
I figure out the problem.
The workingDir of Container in our Pod is /workspace, so the mkdir will create directory based that path.

So there are two scenario:

1. Targetpath is AP， then the path will be create as what it look like, for example: /pengli/builtImage
2. Targetpath is relative path (no "/" at beginning), then a prefix /workspace will be added.

The outputs.resources.builtImage.path believe the targetpath is always relative path, so it alway add /workspace, that's why error raised.

I think, we should document it at least.

[afrittoli]

@vdemeester
I figure out the problem.
The workingDir of Container in our Pod is /workspace, so the mkdir will create directory based that path.

So there are two scenario:

1. Targetpath is AP， then the path will be create as what it look like, for example: /pengli/builtImage
2. Targetpath is relative path (no "/" at beginning), then a prefix /workspace will be added.

The outputs.resources.builtImage.path believe the targetpath is always relative path, so it alway add /workspace, that's why error raised.

I think, we should document it at least.

Thanks for looking into this. The inconsistent behaviour sounds like a bug to me.

@vdemeester @bobcatfish @dlorenc @skaegi do we want to support mounting resources outside of /workspace?
I would say yes, so the absolute path should be honoured by outputs.resources.builtImage.path

[vincent-pli]

@vdemeester @afrittoli
So should we fix this issue at outputs.resources.builtImage.path side?

[ghost]

@vincent-pli Yes, I think the right solution is for outputs.resources.builtImage.path to correctly report the directory instead of prepending /workspace to the target path.

I see that your current PR to solve this issue prepends /workspace - do you want to close that PR and start a new one for this fix or update it to correct the variable interpolation value?

[vincent-pli]

@sbwsg
Sure, I can do that.

[bobcatfish]

For whatever reason targetPath has always been relative to /workspace https://github.com/tektoncd/pipeline/blob/master/docs/resources.md#controlling-where-resources-are-mounted

Admittedly very confusing 😅