Is it possible for Jenkins to automatically detect and build newly created tags in a git repo?

Question

It would be nice for our Jenkins CI server to automatically detect, deploy and build tags as they are created in our Github repository.

Is this possible?

Answer 1

To overcome the drawback of @oberlies' answer that all tags will be built I'm using a special trigger build instead. The trigger build uses the same git repository and branch as the main build and the following (post) build steps.

Build -> Execute shell:

# Get the most recent release tag.
PATTERN="release-tag-[0-9][0-9]-[0-9][0-9][0-9][0-9]"
TAG=$(git log --tags=$PATTERN --no-walk --pretty="format:%d" | grep -m 1 -o $PATTERN)

# Due to a Jenkins limitation (https://issues.jenkins-ci.org/browse/JENKINS-8952)
# when passing environment variables we have to write the tag to a file and
# inject it later again.
mv release.properties release-old.properties || true
echo "TAG = $TAG" > release.properties

# Fail the build if the most recent release tag did not change.
! diff release.properties release-old.properties

Build -> Inject environment variables:

Properties File Path: release.properties

Post-build Actions -> : Trigger parameterized build on other projects

Projects to build: 
Trigger when build is: Stable
Parameters: TAG=$TAG

Finally, in your main build, tick "This build is parameterized" with the following string parameter

Name: TAG
Default Value: 

And in the "Source Code management" section use "$TAG" in the "Branches to build" field.