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Troubleshooting Git Clone Authentication Failures Inside Docker

Use this when git clone works on the host but fails inside a Docker build or running container.

Quick Read

  • Symptom: Use this when git clone works on the host but fails inside a Docker build or running container.
  • Check first: Verify if the correct Git repository URL is being used.
  • Risk: Changes system state

Symptoms

Git clone fails due to authentication errors when executed inside a Docker container.

Environment

Docker container running a Linux distribution with Git installed.

Most Likely Causes

Incorrect Git credentials or SSH keys not configured properly within the Docker container.

What to Check First

  1. Verify if the correct Git repository URL is being used.
  2. Check if the Docker container has access to the necessary SSH keys or credentials.

Fix Steps

  1. Check the Git repository URL for correctness.

    Ensure the URL format is correct (e.g., https:// or git@).

    Example pattern only. Adjust for your environment before running.

    echo 'Repository URL: <your-repo-url>'
  2. Verify if SSH keys are present in the Docker container.

    Check for the presence of SSH keys in the default location.

    Safe to run: read-only

    ls -la ~/.ssh
  3. Add SSH keys to the Docker container if missing.

    Copy the SSH keys from the host to the container.

    Safe to run: read-only

    docker cp ~/.ssh/id_rsa <container_id>:/root/.ssh/id_rsa
docker cp ~/.ssh/id_rsa.pub <container_id>:/root/.ssh/id_rsa.pub
  4. Set the correct permissions for the SSH keys.

    Ensure that the SSH private key has the correct permissions.

    Changes system state: review before running

    docker exec <container_id> chmod 600 /root/.ssh/id_rsa
  5. Test SSH connection to the Git server.

    Verify that the SSH connection works without issues.

    Safe to run: read-only

    docker exec <container_id> ssh -T git@<git-server>
  6. Attempt to clone the repository again.

    Retry the git clone command after resolving authentication issues.

    Safe to run: read-only

    docker exec <container_id> git clone <your-repo-url>

Validation

  • Confirm that the repository has been cloned successfully.
  • Check for the presence of the cloned directory.

Logs to Check

  • /var/log/syslog
  • /var/log/auth.log

Rollback and Escalation

    Escalate When

    • If the issue persists after following all steps, escalate to the DevOps team for further investigation.

    Edge Cases

    • Using a different user than root inside the container may require additional permissions.
    • If using HTTPS, ensure that the correct username and password/token are used.

    Notes from the Field

    • Always ensure that the Docker container has network access to the Git server.
    • Consider using Docker secrets for managing sensitive information like SSH keys.