See https://integration.wikimedia.org/ci/job/wikimedia-toolhub-pipeline-test/2/console for an example failure of this type.

I'm actually unsure now if the problem is exactly the set +x injection or instead that the ${build-npm.imageID} is possibly not being expanded properly...

In T266196#6570255, @bd808 wrote:

I'm actually unsure now if the problem is exactly the set +x injection or instead that the ${build-npm.imageID} is possibly not being expanded properly...

Yeah, I totally misread the Jenkins output and Groovy code. The problem I am having is that the image id is not being expanded. It is instead being passed literally to the runner as shown in exec docker run --rm sha256:'${build-npm.imageID}' 'lint'. Does this mean that my .pipeline/config.yaml is malformed?

pipelines:
  test:
    blubberfile: blubber.yaml
    stages:
      - name: build-python
        build: dev-python
        run: false
      - name: lint-python
      - name: test-python
        run:
          env:
            DJANGO_SECRET_KEY: dummy value for use in tests
            DB_ENGINE: django.db.backends.sqlite3
            DB_NAME: ":memory:"

      - name: build-npm
        build: npm-run
        run: false
      - name: lint-npm
        run:
          image: '${build-npm.imageID}'
          arguments:
            - lint
      - name: test-npm
        run:
          image: '${build-npm.imageID}'
          arguments:
            - test

    execution:
      - [build-python, lint-python]
      - [build-python, test-python]
      - [build-npm, lint-npm]
      - [build-npm, test-npm]

Change 635672 had a related patch set uploaded (by BryanDavis; owner: Bryan Davis):
[wikimedia/toolhub@main] .pipeline: Stop reusing a built container for npm

https://gerrit.wikimedia.org/r/635672