How to determine which branch failed to build if I don't have build information?

With only limited information, indirect methods can be used:

1. Analysis of build logs: If access to CI/CD logs (e.g., Jenkins, GitLab CI, GitHub Actions) is available, they contain information about build runs, including branches and statuses.
2. Checking recent commits in branches: You can manually go through main branches (main, dev) and check the latest commits. Some commits may contain links to incomplete or failed builds.
3. Viewing pull/merge requests: Builds are often triggered when creating PR/MR. Viewing these requests can reveal a branch with a failed build.
4. Checking branch statuses in version control system: In interfaces like GitLab/GitHub/Bitbucket, the status of the last build for each branch is often displayed.

Example of analyzing GitLab CI logs using grep:

# Check logs in last_pipeline.log for failed builds in branches
grep 'status: failed' last_pipeline.log | grep 'ref:'

Example of checking branch statuses via Git:

# Get a list of all local branches
git branch

# Switch to a potentially problematic branch (e.g., feature/new-feature)
# and look for build mentions in commit logs
git checkout feature/new-feature
git log --grep="build failed"

Table of possible information sources:

Source	Advantages	Disadvantages
CI/CD Logs	Precise information about status and branch	Requires access to logs
Commit Messages	May contain explicit build mentions	Not always informative
Pull/Merge Requests	Explicitly links branch and build	Build may have succeeded, but PR/MR not closed
VCS Branch Status	Quick overview	May not show the full build history