Unable to use env variable in a container name

[lukasz-mitka]

Describe the bug
I'm trying to use env variable inside container name and I'm getting Startup Failures.

To Reproduce
Use env variable in a container name specifier. Example:

name: env in container name

on:
  push:

env:
  IMAGE: ubuntu:18.04

jobs:
  build:
    runs-on: ubuntu-latest
    container: ${{ env.IMAGE }}
    steps:
      - name: env
        run: echo ${{ env.IMAGE }}

Expected behavior
Workflow should start with container from env.IMAGE
env context should be available: https://docs.github.com/en/actions/learn-github-actions/contexts#context-availability

Runner Version and Platform

Can't tell, it doesn't start.

OS: Linux

What's not working?

Workflow doesn't start.

Status Startup failure

Invalid workflow file: .github/workflows/env_container_name.yaml#L12
The workflow is not valid. .github/workflows/env_container_name.yaml (Line: 12, Col: 16): Unrecognized named-value: 'env'. Located at position 1 within expression: env.IMAGE

Found this and it's missing env:

runner/src/Sdk/DTPipelines/workflow-v1.0.json

Lines 367 to 373 in ca7be16

	"container": {
	"context": [
	"github",
	"needs",
	"strategy",
	"matrix",
	"vars"

Job Log Output

n/a

Runner and Worker's Diagnostic Logs

n/a

[fhammerl]

Hey @lukasz-mitka, thanks for submitting this one. It does seem like there's a mismatch between what's documented and what's possible.

Since the process of parsing the yaml includes both runner- and server-side operations, we won't be able to resolve this issue immediately with just a runner PR / change.

I will post an update here once we're at that point.

[renakdup]

Jobs has no access to env variables, but steps can access. It's frustrated me.
I agree that we need to fix this issue, that looks unlogical, and a lot of developers waste time reinventing the wheel.

I found related issues, and this issue was not solved since 2021: #1189

Solving this problem can provide Github action more flexibility.