Here we show a way to build RPMs with Jenkins using a Makefile. Now we will show a Jenkins based build (without create Makefle).

So, you can directly create a new Job in your Jenkins using the Free Style creation method and adding a shell build step. Inside the text area you can put something like this:

testrel=$(/usr/bin/git diff HEAD~1 | awk '/[\t ]+[\t ]Release/ {
print "NEWREL"; exit 0 }')
if [ "$testrel" != "NEWREL" ]; then
    echo "There is no new release in the rpm spec files - do not rebuild."
    exit 0
fi
rm -rf rpmbuild ${JOB_NAME}.tar.gz
mkdir -p rpmbuild/{BUILD,RPMS,SOURCES/${JOB_NAME},SPECS,SRPMS}
tar --exclude-vcs --exclude='rpmbuild' -cp  | (cd
rpmbuild/SOURCES/${JOB_NAME} ; tar xp)
cd ${WORKSPACE}/rpmbuild/SOURCES
tar -cvzf ${JOB_NAME}.tar.gz ${JOB_NAME}
cd ${WORKSPACE}
cp misc/specs/.spec rpmbuild/SPECS/
sed -i "s/^[\t ]Source0:./Source0: ${JOB_NAME}.tar.gz/g" rpmbuild/SPECS/.spec
sed -i "s/^[\t ]%setup[\t ]+-n[\t ]+./%setup -n ${JOB_NAME}/g"
rpmbuild/SPECS/.spec
rpmbuild --define "_topdir %(pwd)/rpmbuild" -ba rpmbuild/SPECS/.spec

The first line of the script checks for git log to find if Release* is changed inside the spec file (that should be naturally committed as resources of your project); the project will be built only if you modified the Release inside the spec!

After that the operation is like the one proposed in the Makefile: creation of tar.gz source archive, creation of rpm-build directories, build rpm.

So, you can choose to put your build code completely inside Jenkins or create a Makefile and link your build process with your project (changes in project that requires build process changes won't impact Jenkins configuration.