No merge base found between HEAD and refs/heads/master for PR analysis

[jessk (Jessie Kim)]

Hello, I’m still relatively new to SonarQube so forgive me if there are any mistakes/misinterpretations.

Whenever the scan job from the GitLab CI/CD pipeline runs for a pull request, I want the sonar scanner to find the common ancestor between the PR and master and use that to find the new or changed code to scan for SonarQube. However, it sometimes doesn’t find this merge base, resulting in the new code on the PR analysis report being completely wrong because the PR branch is behind the master branch analysis report on the SonarQube portal (the new code is set to “Previous Version”).

I first run git checkout branch_name_here and make dummy changes, then I push onto GitLab as a PR (Merge Request in Gitlab’s case) and run the scan job (as it is manual).

To run sonar scanner, it is unzipped using the Dockerfile so that it can be run in the docker build environment and then is run in the Gitlab CI/CD pipeline as part of a scan job after the build wrapper is finished observing the clean build.

What I tried so far in the .gitlab-ci.yml file to try to fix the issue:

1. Make the GIT_DEPTH variable set to 0
2. Run the git fetch --all command within the scan job
3. Run git fetch origin
4. Make dummy changes on one file and push onto the pipeline (Sometimes works, sometimes not. For example, we made a dummy PR with this change, and it did find the merge base, the second commit and run on the pipeline it did not find a merge base)
5. Run the pipeline on various runners (sometimes they find the merge base, most of the time they do not, regardless of runner)

Job log before actual analysis:

INFO: Load project repositories
INFO: Load project repositories (done) | time=44ms
INFO: SCM collecting changed files in the branch
WARN: No merge base found between HEAD and refs/heads/master
INFO: SCM collecting changed files in the branch (done) | time=7159ms

Job log at the near end of the scan job:

INFO: SCM writing changed lines
WARN: No merge base found between HEAD and refs/heads/master
INFO: SCM writing changed lines (done) | time=8703ms
INFO: Analysis report generated in 8914ms, dir size=11.3 MB

The version of SonarQube I’m using is 9.9.1 developer edition. Java version is v17.
If there is any information I missed sharing please let me know, thank you!

[ganncamp (G Ann Campbell)]

Hi,

Welcome to the community!

You mentioned GitLab. Is it doing a merge commit before analysis? If so, that’s likely the problem.

If not, here are some other possibilities:

SonarCloud finds files that are not related to a Pull Requests as "new code"

I had this issue as well. Thought I would reply here with my solution in case it helps anyone. What happens was that in the CI server machine in the git repo there was an old local branch of the same name as the branch provided to the sonar-scanner -Dsonar.pullrequest.base parameter. In my case it was a branch called “develop”. So even though at the time of the build the local “develop” was not checked out, per the comment above sonar-scanner gives priority first to checking refs/heads/deve…

'New Code' on feature branch being polluted with details from mainline

Problem popped up again allowing me to refine the work-around. Good News. I think the problem is resolved via forcing a ‘git fetch’ on the branch when Jenkins builds it. What worked this time: Problem occurred. A build died at the sonarqube quality gate. I manually logged into build box, went to workspace for the affected build. ran the ‘git merge …’ command - confirmed it indicated an old commitid ran a ‘git fetch’ - saw a bunch of stuff come over ran the ‘git merge …’ command - confirme…

 
Ann