title: Container builder dockerfile with gcloud commands
body: <p>I have a container builder step</p>
  
  <pre><code>steps:
  - id: dockerbuild
    name: gcr.io/cloud-builders/docker
    entrypoint: 'bash'
    args:
    - -c
    - |
      docker build . -t test 
  images: ['gcr.io/project/test']
  </code></pre>
  
  <p>The Dockerfile used to create this test image has gsutil specific commands like</p>
  
  <pre><code>FROM gcr.io/cloud-builders/gcloud
  RUN gsutil ls
  </code></pre>
  
  <p>When I submit a docker build to container builder service using</p>
  
  <pre><code>gcloud container builds submit --config cloudbuild.yml
  </code></pre>
  
  <p>I see the following error</p>
  
  <pre><code>You are attempting to perform an operation that requires a project id, with none configured. Please re-run gsutil config and make sure to follow the instructions for finding and entering your default project id.
  The command '/bin/sh -c gsutil ls' returned a non-zero code: 1
  ERROR
  ERROR: build step 0 "gcr.io/cloud-builders/docker" failed: exit status 1
  </code></pre>
  
  <p>My question is, how do we use gcloud/gsutil commands inside the DockerFile so that I can run inside a docker build step ?</p>