Feature Request: Nested array/object parameters

[lbernick]

Feature request

Support specifying array and object params within object params, e.g.:

params:
- name: event
  value:
    repository:
      owner: tektoncd
      name: pipelines

Use case

• putting full event bodies into parameters, which could be helpful for supporting FRs like Provide a mechanism to more easily access the "event" in a workspace in pipelines triggers#1574 (FYI @skaegi)
• producing results from matrixed taskruns of type array of array (where the matrixed taskrun produces array results) or array of object (where the matrixed taskrun produces object results) (FYI @pritidesai)

Challenges

• determining whether there should be a cap on level of nesting or param size

[pritidesai]

Thanks @lbernick for creating this feature request 👍

There is an additional use case from our users for an array of object in matrix.

matrix works great with an implicit and explicit combinations. But matrix does not support dynamic list of combinations specified by the users through the pipelineRun or a trigger.

For example, with a shared pipeline, some users would like to specify 2 combinations while some would like to initiate the same pipeline using 3 combinations.

The following example works great where the pipeline controller generates all possible combinations of both platform and browser. The users can specify a list of platforms and browsers at run time. The same pipeline can be invoked for 2 platforms and also for 3 platforms.

    matrix:
      params:
        - name: platform
          value: $(params.platforms[*])
        - name: browser
          value: $(params.browsers[*])
  ...

We are missing the same level of dynamism with an explicit combinations. Taking an example of matrix to build an image with a specific path for each image would not work if the list of images are specified at the pipelineRun level. The following example is part of the pipeline and the pipeline will always create three instances of the same build task.

    matrix:
        include:
          - name: build-1
            params:
              - name: IMAGE
                value: "image-1"
              - name: DOCKERFILE
                value: "path/to/Dockerfile1"
          - name: build-2
            params:
              - name: IMAGE
                value: "image-2"
              - name: DOCKERFILE
                value: "path/to/Dockerfile2"
          - name: build-3
            params:
              - name: IMAGE
                value: "image-3"
              - name: DOCKERFILE
                value: "path/to/Dockerfile3"
  ...

The concept of nested array and object param will help solve this use case where the same pipeline can be invoked with any number of explicit combinations.

matrix:
  params:
    - name: list-of-platform-browser-object
      value: $(params.list-of-platform-browser-object[*])