How to trigger a build only if changes happen on particular set of files

Question

How do I tell Jenkins Hudson to trigger a build only for changes on a particular project in my Git tree

User · Answer

I answered this question in another post:

How to get list of changed files since last build in Jenkins/Hudson

#!/bin/bash

set -e

job_name="whatever"
JOB_URL="http://myserver:8080/job/${job_name}/"
FILTER_PATH="path/to/folder/to/monitor"

python_func="import json, sys
obj = json.loads(sys.stdin.read())
ch_list = obj['changeSet']['items']
_list = [ j['affectedPaths'] for j in ch_list ]
for outer in _list:
  for inner in outer:
    print inner
"

_affected_files=`curl --silent ${JOB_URL}${BUILD_NUMBER}'/api/json' | python -c "$python_func"`

if [ -z "`echo \"$_affected_files\" | grep \"${FILTER_PATH}\"`" ]; then
  echo "[INFO] no changes detected in ${FILTER_PATH}"
  exit 0
else
  echo "[INFO] changed files detected: "
  for a_file in `echo "$_affected_files" | grep "${FILTER_PATH}"`; do
    echo "    $a_file"
  done;
fi;

You can add the check directly to the top of the job's exec shell, and it will exit 0 if no changes are detected... Hence, you can always poll the top level for check-in's to trigger a build.

User · Answer

While this doesn t affect single jobs  you can use this script to ignore certain steps if the latest commit did not contain any changes         Check a folder if changed in the latest commit     Returns true if changed  or false if no changes      def checkFolderForDiffs path        try              git diff will return 1 for changes  failure  which is caught in catch  or            0 meaning no changes          sh  git diff --quiet --exit-code HEAD 1  HEAD   path           return false       catch  err            return true          if   checkFolderForDiffs  api              API folder changed  run steps here

User · Answer

The Git plugin has an option  excluded region  to use regexes to determine whether to skip building based on whether files in the commit match the excluded region regex   Unfortunately  the stock Git plugin does not have a  included region  feature at this time  1 15   However  someone posted patches on GitHub that work on Jenkins and Hudson that implement the feature you want   It is a little work to build  but it works as advertised and has been extremely useful since one of my Git trees has multiple independent projects   https   github com jenkinsci git-plugin pull 49  Update  The Git plugin  1 16  now has the  included  region feature

User · Answer

I wrote this script to skip or execute tests if there are changes      bin bash  set -e -o pipefail -u  paths    while     1      --     do     paths      1     shift done shift  if git diff --quiet --exit-code    BASE BRANCH -origin master    HEAD   paths      then     echo  No changes in   paths      skipping        1 gt  amp 2     exit 0 fi echo  Changes found in   paths      running        1 gt  amp 2  exec        So you can do something like     scripts git-run-if-changed sh  cmd vendor go mod go sum fixtures  tools  -- go test

User · Answer

Basically  you need two jobs  One to check whether files changed and one to do the actual build   Job  1  This should be triggered on changes in your Git repository  It then tests whether the path you specify   src  here  has changes and then uses Jenkins  CLI to trigger a second job   export JENKINS CLI  java -jar  var run jenkins war WEB-INF jenkins-cli jar  export JENKINS URL http   localhost 8080  export GIT REVISION  git rev-parse HEAD  export STATUSFILE  WORKSPACE status  BUILD ID txt    Figure out  whether  src  has changed in the last commit git diff-tree --name-only HEAD   grep src    Exit with success if it didn t       exit 0    Trigger second job  JENKINS CLI build job2 -p GIT REVISION  GIT REVISION -s   Job  2  Configure this job to take a parameter GIT REVISION like so  to make sure you re building exactly the revision the first job chose to build

User · Answer

If you are using a declarative syntax of Jenkinsfile to describe your building pipeline  you can use changeset condition to limit stage execution only to the case when specific files are changed  This is now a standard feature of Jenkins and does not require any additional configruation software   stages       stage  Nginx             when   changeset  nginx             steps               sh  make build-nginx              sh  make start-nginx                      You can combine multiple conditions using anyOf or allOf keywords for OR or AND behaviour accordingly   when       anyOf           changeset  nginx             changeset  fluent-bit             steps       sh  make build-nginx      sh  make start-nginx

User · Answer

You can use Generic Webhook Trigger Plugin for this   With a variable like changed files and expression   commits      modified   added   removed        You can have a filter text like  changed files and filter regexp like  folder subfolder         if folder subfolder is the folder that should trigger builds

User · Answer

If the logic for choosing the files is not trivial  I would trigger script execution on each change and then write a script to check if indeed a build is required  then triggering a build if it is

[git] How to trigger a build only if changes happen on particular set of files

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