How to retrieve the git branch name that was built by Jenkins when using inverse branch selection strategy?

Question

We have one Jenkins job which builds every branch except master when there are new commits. This behavior can be configured via git plugin's 'choosing strategy:inverse' so that it listens to every branch except a specified branch.

This functions very nicely. But the problem is that GIT_BRANCH environment variable always refers to the excluded branch('origin/master' in our case). How to query the actual branch that was built by Jenkins?

Currently I am using a workaround that I grep it from generated changelog.xml. But it happens sometimes that changelog.xml is empty when Jenkins switches between different branches and I cannot find this info. What is the correct way of retrieving/querying from Jenkins the branch that was actually built?

Answer 1

Because git never checks out a branch just a commit directly you have to do the following:

To get the sha of the checked out commit:

git rev-parse HEAD

To get the all branches that commit is under:

git branch -a --contains SHA

The out put of the second command could look like this

master
remotes/origin/HEAD -> origin/master
remotes/origin/develop

Answer 2

I successfully used this syntax:

GIT_BRANCH=`git rev-parse HEAD | git branch -a --contains | grep remotes | sed s/.*remotes.origin.//`

Answer 3

Looks like it's a Jenkins bug? You can grab in your build script the name of the checked out branch with this:

git symbolic-ref -q --short HEAD

Actually Jenkins has the working copy in detached HEAD, which is why git branch returns "no branch". See this quite detailed answer for digging into reconciliation with between a detached HEAD and a branch.

Answer 4

I can't believe how hard this is. I'm doing this for Jenkins as well. I piggypacked off Piotr Kuczynski's solution:

branch=`git rev-parse HEAD | git branch -a --contains | grep remotes | sed s/.*remotes.origin.//`
branch=`echo $branch | awk '{print $NF}'`

Because sometimes, as Matt Kantor pointed out, Piotr's solution gives a lot of junk back. But the last word in that junk appears to always be correct. Note that this solution only works if the ref you're using corresponds exactly with a branch that exists on remote (so local branches will not work).