Is the `env` context available in `jobs.<job-name>.container` or not?

I’m setting up my first ever workflow and I’m getting a bit confused.

My workflow definition looks like this:

# Inspired by:
# <https://docs.github.com/en/actions/publishing-packages/publishing-docker-images>
# and the "Django test" workflow template from GitHub.

name: Build and test

on:
  push:
    branches:
      - master
      - development
      - "feature/**"

env:
  REGISTRY: ghcr.io
  IMAGE_NAME: ${{ github.repository }}

jobs:
  build-and-push-docker-image:
    runs-on: ubuntu-latest
    permissions:
      contents: read
      packages: write

    steps:
      - name: Checkout repository
        uses: actions/checkout@v2

      - name: Log in to the Container registry
        uses: docker/login-action@f054a8b539a109f9f41c372932f1ae047eff08c9
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Extract metadata for Docker image
        id: meta
        uses: docker/metadata-action@98669ae865ea3cffbcbaa878cf57c20bbf1c6c38
        with:
          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}

      - name: Build and push Docker image
        uses: docker/build-push-action@ad44023a93711e3deb337508980b4b5e9bcdc5dc
        with:
          context: .
          file: ./Dockerfile-www
          push: true
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}

  run-django-tests:
    needs: build-and-push-docker-image
    runs-on: ubuntu-latest
    container:
      image: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
      credentials:
        username: ${{ github.actor }}
        password: ${{ secrets.GITHUB_TOKEN }}
    steps:
      - name: Run tests
        run: python ./manage.py test

The first job, build-and-push-docker-image, runs just fine. It builds and pushes a docker image to GHCR. The second job is causing problems for me.

When I started working on this last week, I first assumed that the env context is available in jobs.<job-name>.container, which I use for getting the correct REGISTRY and IMAGE_NAME.

After digging around, I found out that the env context isn’t available there. Today when I resumed work, The Context Availability documentation suddenly listed env as available there. I first thought I was either mad or didn’t read things properly (or both). But it looks like it was recently added to the docs.

Now my question is: Is it actually avaliable? I’ve found this answer to another post, where @blueskyjunkie seems to have been able to access the env context from within there.

But when I try, I get the following error:

The workflow is not valid. .github/workflows/workflow.yml (Line: 55, Col: 14): Unrecognized named-value: ‘env’. Located at position 1 within expression: env.REGISTRY

Line 55 is: image: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}

Can somebody help me? Am I doing something wrong in my workflow definition? Has the env only recently been made available and my job runners are for some reason not up to date? Do I need to toggle a switch somewhere to make it available? What is going on?