Warn users about legacy /ci URL suffix in runner configuration
What does this MR do?
In GitLab Runner versions before 1.0.0, the runner URL was configured with a /ci suffix (e.g., https://gitlab.example.com/ci). This suffix was deprecated in 2016 via !289 (merged), but some legacy configurations still use it.
While the /ci suffix is automatically stripped in most contexts, it can cause Git submodule authentication failures when GIT_SUBMODULE_FORCE_HTTPS is enabled. The suffix interferes with Git URL rewriting rules, causing submodules to fail with "could not read Username" errors.
This commit adds:
- A WarnOnLegacyCIURL() method that logs a warning when a runner configuration contains the /ci suffix.
- The warning is triggered during configuration loading so users are notified at startup.
- Documentation explaining the issue and how to resolve it.
The warning message directs users to remove the /ci suffix from their config.toml and links to documentation with detailed resolution steps.
Related to gitlab#581678 (closed)
Why was this MR needed?
What's the best way to test this MR?
What are the relevant issue numbers?
Edited by Stan Hu