Multi-account AWS CodeCommit access

Our developers access internally owned git CodeCommit repos across multiple AWS accounts. These AWS accounts are owned by us. It is important to qualify AWS/CodeCommit ownership here. Client owned CodeCommit access best practice is through IAM roles (out of scope for this post).

Scope of this post:

  1. organizational CodeCommit access spanning two AWS accounts
  2. concurrent access to repos in both AWS accounts

Solution options:

  1. Access CodeCommit in both accounts using git-remote-codecommit
  2. Access CodeCommit in 1st account using SSH & the 2nd using git-remote-codecommit.

A “no-no-option” worth noting: accessing CodeCommit in both AWS accounts using SSH.

Our reference implementation addresses both viable solution options.

  1. Generate AWS access key and secret access key for an IAM entity having AWSCodeCommitFullAccess
  2. Create AWS cli profile(s)
    aws --profile account1-gov configure
    ...
    Default region name [None]: us-gov-west-1
    Default output format [None]: json
  3. Install git-remote-codecommit
    pip3 install git-remote-codecommit
  4. Clone repos. Enjoy!
    git clone codecommit://account1-gov@repo-name repo-name-gc

Important

Do not use GRC HTTP clone URL without profile (e.g., account1-gov) when concurrent access to account2 with SSH is in place.

AWS instance profile-based private Git repository access

Secure and private Git repository access enables teams. However, using an IAM user with SSH keys authenticating to private Git repository is not recommended. Why?

  1. Long lived key storage violates just-in-time access.
  2. IAM-user driven git SSH key management does not enable CI/CD.

IAM roles and git-remote-codecommit to the rescue!

Our AWS reference implementation:

  1. A private subnet with external connectivity, i.e., NAT’d subnet. No IGW.
  2. Two IAM roles with AWSCodeCommitReadOnly for CI/CD and AWSCodeCommitPowerUser for developers
  3. AWS CodeCommit repository
  4. Jenkins Docker image with git-remote-codecommit

CI/CD setup process:

  1. Configure the GRC HTTPS CodeCommit URLs in Jenkins Dockerfile. CodeCommit:
  2.  Provision AWS infrastructure for Jenkins with the instance profile or EKS role leveraging policy with AWSCodeCommitReadOnly
  3. Run Jenkins pipeline leveraging git clone.
  4. Done!
This process is repeatable for developer access via IAM role with AWSCodeCommitPowerUser policy.