Cloud Build does not populate Git submodules

I have a Google Cloud Build trigger which I've set to a Github repo which has the option selected Cloud Build configuration file (yaml or json).

The repo has a submodule but I'm afraid the submodule is not populated by default. When I create a Compute VM from the resulting Docker image from the Cloud Build process, the logs show:

DEFAULT 2023-05-22T01 [resource.labels.instanceId: XXX-build] ImportError: cannot import name 'mysubmodule' from 'mysubmodule' (unknown location)

I believe the issue is the submodules do not pull like when using git clone on a desktop. So I add the git submodule update --init command in the cloudbuild.yaml file below but the issue is the Cloud Build process doesn't understand the submodule command.

I've tried:

Changing the path to SSH gitpath: Cloud build failing on git submodules

Adding git command in cloudbuild.yaml:

- name: "gcr.io/cloud-builders/git"
  args:
    - submodule update --init --recursive

Result

Step #0: git: 'submodule update --init --recursive' is not a git command. See 'git --help'.

There is also this bug: https://issuetracker.google.com/issues/123060361

Solution

2025 Update: The manage-dependencies feature in Cloud Build now supports submodules. My source lives in Github, so I'm providing some documentation for what I did. YMMV.

create Developer Connect connections to Github for the repository and its submodules.
service account needs the "Developer Connect Read Token Accessor" role
you can view your connections, click the three dots, and copy the resource path
modify your cloudbuild.yaml. Add the top-level dependencies key to clone the submodule and then the project. E.g.:

dependencies:
  - gitSource:
      repository:
        developerConnect: 'projects/my-project-0001/locations/us-central1/connections/github-kenberland/gitRepositoryLinks/kenberland-submodule'
      revision: master
      recurseSubmodules: false
      depth: 1
      destPath: submod
  - gitSource:
      repository:
        developerConnect: 'projects/my-project-0001/locations/us-central1/connections/github-kenberland/gitRepositoryLinks/kenberland-my-project'
      revision: master
      recurseSubmodules: true
      depth: 1
      destPath: .