GitLab: Ignore username from Git credential input when looking up and generating credentials

[tjuchniewicz]

Version

2.7.0.0

Operating system

Windows

OS version or distribution

Windows 11

Git hosting provider(s)

GitLab

Other hosting provider

No response

(Azure DevOps only) What format is your remote URL?

None

Can you access the remote repository directly in the browser?

Yes, I can access the repository

Expected behavior

Expected Behavior

The GitLab provider should:

1. Completely ignore the username from Git's credential input with OAuth

Rationale

• Using the input username can cause incorrect credential lookups and confusing authentication prompts

Actual behavior

Current Behavior

When Git passes a username in the credential request (e.g., username=test when remote.origin.url=https://test@repo.git), the GitLab provider:

1. User runs git pull
2. GCM checks for token for user test - token is missing (not in cache, that's OK)
3. GCM asks user to login using browser
4. GCM Stores token in cache with user oauth (not test)
5. git pull is successful
6. User runs git pull again
7. GCM checks for token for user test - token is not found due to invalid user!
8. GCM asks user again to login using browser

Logs

No response

[tjuchniewicz]

Simple workaround is to remove user name from Git url. Not sure if it's worth to fix this issue. Maybe just add more logging to easily debug such issue.

[mjcheetham]

Hello! This is expected behaviour. Git credential helpers should respect the username field when passed by Git. You'll also find this the case with the contrib helpers such as wincred or osxkeychain.

Is there a reason why you're including a username (that is not the correct user) in the remote URL?

[tjuchniewicz]

We migrated from the legacy repository to GitLab.
In the legacy setup, users had to include a username in the repository URL. During migration, some users copied and pasted the old URL (changing host part only), not realizing that the embedded username is no longer valid in GitLab.

If changing this behavior is not feasible, we should add trace-level logging to make this issue easier to diagnose.
In my case, I had to add custom logs to the GCM source code, then compile and distribute a custom GCM build to identify the root cause.

This is expected behaviour. Git credential helpers should respect the username field when passed by Git.

But currently credential helper does it only partially, when storing token in cache, username is ignored and oauth is always used as username.