I have two or more Docker images where the latter ones are based on the first image. I want to build them all with Google Cloud Build and have the following multi-step cloudbuild.yaml:

steps:
  - name: 'gcr.io/cloud-builders/docker'
    args: ['build', '-t', 'gcr.io/$PROJECT_ID/lh-build', './src']

  - name: 'gcr.io/cloud-builders/docker'
    args: ['build', '-t', 'gcr.io/$PROJECT_ID/lhweb', './src/LHWeb']


images:
  - gcr.io/$PROJECT_ID/lh-build
  - gcr.io/$PROJECT_ID/lhweb

When I run this build config, I can see the following error:

Step 1/6 : FROM eu.gcr.io/logistikhelden/lh-build manifest for eu.gcr.io/logistikhelden/lh-build not found

I then tried to push the image after the first step:

...
  - name: 'gcr.io/cloud-builders/docker'
    args: ['push', 'gcr.io/$PROJECT_ID/lh-build']
...

The same problem remains, though. Any idea whats wrong here?