Results "interpolation" in embedded spec (or "results" propagation)

[vdemeester]

Expected Behavior

A "somewhat" consistent behavior when using results and embedded spec. Naively, I would assume the following would work (but it does not).

cat <<'EOF' | kubectl create -f -
---
apiVersion: tekton.dev/v1
kind: Task
metadata:
  name: uid-task
spec:
  results:
    - name: uid
  steps:
    - name: uid
      image: alpine
      command: ["/bin/sh", "-c"]
      args:
        - echo "1001" | tee $(results.uid.path)
---
apiVersion: tekton.dev/v1
kind: PipelineRun
metadata:
  name: uid-pipeline-run
spec:
  pipelineSpec:
    tasks:
    - name: add-uid
      taskRef:
        name: uid-task
    - name: show-uid
      taskSpec:
        steps:
          - name: show-uid
            image: alpine
            command: ["/bin/sh", "-c"]
            args:
              - echo $(tasks.add-uid.results.uid)
EOF

Actual Behavior

The above example fails with /bin/sh: tasks.add-uid.results.uid: not found. My guess is that, we do have params and workspace propagation on embedded spec, but we do not have them for results.

Steps to Reproduce the Problem

1. Run the command above
2. See it fail
3. …

Additional Info

• Kubernetes version: 1.25.0
• Tekton Pipeline version: v0.50.x

As said above, this might be more a feature request than a bug as, I feel this is mainly because we do not "propagate" results to embedded spec. This does feel inconsistent as we do it for other fields (like params and workspaces).

cc @jerop @lbernick

[jerop]

I also think it's a great idea to propagate results as well -- we descoped this as future work in TEP-0107 which proposed propagating parameters -- https://github.com/tektoncd/community/blob/main/teps/0107-propagating-parameters.md#passing-results

[chengjoey]

+1, Execute the above pipelinerun, the two tasks will be executed at the same time, the subsequent implementation of the passing-results function, dose need the user to explicitly specify runAfter, let the show-uid task execute after add-uid

[jerop]

@chengjoey I don't think the user should have to specify runAfter. Currently, we deduce that there's a dependency when a Result is used in Params or When Expressions without users having to specify runAfter. I'd prefer to maintain that behavior.

[chengjoey]

@chengjoey I don't think the user should have to specify runAfter. Currently, we deduce that there's a dependency when a Result is used in Params or When Expressions without users having to specify runAfter. I'd prefer to maintain that behavior.

in pr, i added task steps sub dependency expression to result references, so that the user does not need to specify runAfter`

[jerop]

sounds good, thank you @chengjoey

[vdemeester]

This is fixed by #7100.