User Story:

As a (user persona), I want to be able to:

• Specify the use of GCP marketplace images in the install config

so that I can achieve

• create compute nodes using marketplace images without:
  • editing manifests
  • knowing the details of the particular images

Acceptance Criteria:

Description of criteria:

• worker machinesets are populated with correct marketplace image
• if a field is added to machine pools, openshift explain and repo docs should be updated
• validation to prevent trying to use images for masters

Engineering Details:

• Set the compute node manifest  https://github.com/openshift/installer/blob/master/pkg/asset/machines/gcp/machines.go#L105 
• https://github.com/openshift/installer/blob/master/pkg/asset/machines/gcp/machines.go#L105
• It should be possible to simply have a boolean in the machine pool. For example we could have a field such as compute[0].platform.gcp.useMarketplaceImage. If that is set, pipe the data from above into the worker machine provider spec image field