Support context/matrix variables and Composite Actions inputs in steps of type 'uses' #1479
Description
Describe the enhancement
It is currently not possible to use variables from the matrix (in a regular workflow), or inputs (in a Composite Action) to define the Actions to be used in steps of type uses. The workflow won't start because of a parser/syntax issue: the uses' attribute must be a path, a Docker image, or owner/repo@ref`.
Code Snippet
See https://github.com/hdl/containers/blob/GHA-MWEs/.github/workflows/MWE-1479.yml and https://github.com/hdl/containers/blob/GHA-MWEs/utils/mwe-input-var-in-uses/action.yml:
matrix-var-in-uses-name:
runs-on: ubuntu-latest
strategy:
fail-fast: false
matrix:
action:
- actions/checkout
steps:
- uses: ${{ matrix.action }}@v2
matrix-var-in-uses-version:
runs-on: ubuntu-latest
strategy:
fail-fast: false
matrix:
version:
- v1
- v2
steps:
- uses: actions/checkout@${{ matrix.version }}
matrix-var-in-uses-docker:
runs-on: ubuntu-latest
strategy:
fail-fast: false
matrix:
img:
- debian:bullseye-slim
- debian:buster-slim
steps:
- uses: docker://${{ matrix.img }}
matrix-var-in-uses-docker-tag:
runs-on: ubuntu-latest
strategy:
fail-fast: false
matrix:
img:
- bullseye-slim
- buster-slim
steps:
- uses: docker://debian:${{ matrix.img }}
matrix-var-in-uses-action:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v2
- uses: ./utils/mwe-input-var-in-uses
name: '[HDLC] MWE Input variable in uses'
description: 'Minimal Working Example to reproduce a bug when using an input in a uses step of a Composite Action.'
inputs:
version:
description: 'Version of actions/checkout to use.'
default: 'v2'
required: false
image:
description: 'Name of the container image.'
default: 'asciidoctor/docker-asciidoctor'
required: true
runs:
using: 'composite'
steps:
- uses: actions/checkout@${{ inputs.version }}
- uses: docker://${{ inputs.image }}
with:
args: doc/make.shAdditional information
The inability to use Composite Action inputs in steps of type uses: docker:// is particularly uncomfortable, because it forces using the docker CLI explicitly. Therefore, environment variables and binds need to be manually and explicitly described. See, for instance, the following workaround to the Composite Action above: https://github.com/VUnit/vunit_action/blob/master/action.yml.
Being able to use the context would be a suitable solution to using a local action without explicitly checking out the repository, as discussed in #646 (comment). Precisely, uses: ${{ github.repository }}/.github/myaction@${{ github.ref_name }} would be equivalent to:
- uses: actions/checkout@v2
- uses: ./.github/myaction/cc @thboop, per #646 (comment)
/cc @aramfe