Trigger specific job on push to specific directory - jenkins

Question

We have 12 different projects inside the same repository and have a different job to run for each of these.
I want to know how I can trigger a job only when a change has happened in a specific folder, since running all 12 on every push takes too long to finish.

Answer 1

Well I have hacked a solution that works for us.
First, add an Execute Shell Build Step:
#!/bin/bash
export DIRS="api objects"
DIFF=`git diff --name-only develop`
echo "export RUN_TEST=0" > "$WORKSPACE/RUN_TEST"
for DIR in $DIRS; do
for LINE in $DIFF; do
# Is this file inside an interesting directory?
echo $LINE | grep -e "^$DIR/"
# Checking if it is inside
if [ $? -eq 0 ]; then
echo "export RUN_TEST=1" > "$WORKSPACE/RUN_TEST"
fi
done
done
Here:
api and objects are the 2 directories I want to trigger this Job
develop is the main branch we use, so I want to know how my directories compare to that branch in particular
I create a file $WORKSPACE/RUN_TEST to set a variable if I should or not run it
Then in the time-consuming build steps add:
#!/bin/sh
. "$WORKSPACE/RUN_TEST"
if [ $RUN_TEST -eq 1 ]; then
# Time consuming code here
fi
That way the job is triggered but runs as fast as if it wasn't triggered.
Now I modified it to:
#!/bin/bash
export DIRS="api objects"
DIFF=`git diff --name-only origin/develop`
RUN_TEST=111
for DIR in $DIRS; do
for LINE in $DIFF; do
# Is this file inside an interesting directory?
echo $LINE | grep -e "^$DIR/"
# Checking if it is inside
if [ $? -eq 0 ]; then
RUN_TEST=0
fi
done
done
echo "RUN_TEST=$RUN_TEST"
echo "return $RUN_TEST" > "$WORKSPACE/RUN_TEST"
exit $RUN_TEST
And set Exit code to set build unstable to 111 on all build steps. Then, in all following build steps I did:
#!/bin/bash
# Exit on any error
set -euo pipefail
. "$WORKSPACE/RUN_TEST"
# Rest of build step