TEP-0108: Mapping Workspaces

May 26, 2022 ยท View on GitHub

Summary

This proposal builds on this prior work to reduce verbosity in mapping Workspaces and improve usability of Tekton Pipelines.

Motivation

The verbosity of writing specifications in Tekton Pipelines is a common pain point that causes difficulties in getting-started scenarios. Tasks declare Workspaces they need, while Pipelines declare Workspaces that are shared among its PipelineTasks. The mapping of Workspaces from Pipelines to PipelineTasks is verbose, as shown below:

apiVersion: tekton.dev/v1beta1
kind: Pipeline
metadata:
  name: pipeline
spec:
  workspaces:
    - name: source
  tasks:
    - name: gen-code
      taskRef:
        name: gen-code # gen-code expects a Workspace named "source"
      workspaces:
        - name: source
          workspace: source
    - name: commit
      taskRef:
        name: commit # commit expects a Workspace named "source"
      workspaces:
        - name: source
          workspace: source
      runAfter:
        - gen-code

Proposal

We propose auto-mapping Workspaces from Pipelines to PipelineTasks when the names of the Workspaces declared in the Pipeline and PipelineTask are the same, as shown below:

apiVersion: tekton.dev/v1beta1
kind: Pipeline
metadata:
  name: pipeline
spec:
  workspaces:
    - name: source
  tasks:
    - name: gen-code
      taskRef:
        name: gen-code # gen-code expects a Workspace named "source"
      workspaces:
        - name: source
    - name: commit
      taskRef:
        name: commit # commit expects a Workspace named "source"
      workspaces:
        - name: source
      runAfter:
        - gen-code

The Workspaces will be bound to the Workspaces declared within the Tasks.

To meet conformance requirements, this solution does not mutate the Pipeline specification at runtime. In addition, the validation routine that confirms that Workspaces needed by PipelineTasks are provided will be expanded to handle this proposal.

Users can continue to explicitly map Workspaces, as shown below:

apiVersion: tekton.dev/v1beta1
kind: Pipeline
metadata:
  name: pipeline
spec:
  workspaces:
    - name: source
  tasks:
    - name: gen-code
      taskRef:
        name: gen-code # gen-code expects a Workspace named "output"
      workspaces:
        - name: output
          workspace: source
    - name: commit
      taskRef:
        name: commit # commit expects a Workspace named "source"
      workspaces:
        - name: source
      runAfter:
        - gen-code

References