Note_Tech

All technological notes.

---

Project maintained by simonangel-fong Hosted on GitHub Pages — Theme by mattgraham

Jenkins - Job

Back

• Jenkins - Job
  • Job
    • Trigger
  • Lab: Execute a bash script
  • Lab: Parameterized
    • String Parameters
    • Choose Parameters
    • Boolean Parameters
  • API Call
    • Lab: triger a job via API

---

Job

When creating a job in Jenkins, it creates a new directory in the /var/jenkins_home/workspace/

• /var/jenkins_home/workspace/<job_name>

---

Trigger

Trigger Method	Description
Manual trigger	clicks Build Now in Jenkins. Common for test, staging, or production deployment approval.
SCM polling	Jenkins checks Git regularly for changes, such as every 5 minutes.
Webhook trigger	Repo sends a request to Jenkins when code is pushed or a PR is created.
Scheduled trigger	Runs by cron schedule, such as nightly builds or weekly security scans.
Upstream/downstream trigger	One Jenkins job triggers another job after success or failure.
Parameterized trigger	User or another system starts a job with parameters, such as env=dev or version=1.2.0.
Remote/API trigger	External tools call Jenkins REST API to start a job.
Pull request trigger	Jenkins runs checks automatically when a PR is opened or updated. Common for validation before merge.

• Poll SCM
  • a build trigger mechanism that periodically checks (polls) your Source Control Management system (like Git or SVN) for code changes.
• Cron syntax:

Minute Hour Date Month weekday

---

Lab: Execute a bash script

• Env:
  • Host OS: ubuntu
  • Jenkins Deploy: Docker

---

• Create a shell script

cat > demo-script.sh <<'EOF'
#!/bin/bash

NICKNAME=$1
MSG=$2

echo "Hi, $NICKNAME. This is the message: $MSG"
EOF

chmod +x demo-script.sh

./demo-script.sh Adam "Mission completed."
# Hi, Adam. This is the message: Mission completed.

# copy to docker container
docker ps
# CONTAINER ID   IMAGE                       COMMAND                  CREATED          STATUS          PORTS                                                                                          NAMES
# c818c31087ad   jenkins/jenkins:lts-jdk21   "/usr/bin/tini -- /u…"   32 minutes ago   Up 32 minutes   0.0.0.0:8080->8080/tcp, [::]:8080->8080/tcp, 0.0.0.0:50000->50000/tcp, [::]:50000->50000/tcp   jenkins
docker cp demo-script.sh jenkins:/tmp/demo-script.sh
# Successfully copied 2.05kB to jenkins:/tmp/demo-script.sh

# test in container
docker exec -it jenkins /tmp/demo-script.sh Adam "Mission completed."
# Hi, Adam. This is the message: Mission completed.

• Update the job
  • shell script

/tmp/demo-script.sh Adam "Mission completed."

---

Lab: Parameterized

String Parameters

• Based on previous bash script
• Set parameters
  • “This project is parameterized” -> “String Parameter”

• Update job shell script

echo "NICKNAME: $NICKNAME"
echo "MSG: $MSG"
/tmp/demo-script.sh $NICKNAME $MSG

---

Choose Parameters

• Update shell script

/tmp/demo-script.sh $NICKNAME $MSG $SUBFIX

• execute

---

Boolean Parameters

• Update shell script

cat > demo-script.sh <<'EOF'
#!/bin/bash

NICKNAME=$1
MSG=$2
FLAG=$3

if [ "$FLAG" = "true" ]; then
  echo "Hi, $NICKNAME. This is the message: $MSG"
else
  echo "Flag is not true."
fi

EOF

# test locally
./demo-script.sh Adam "Mission completed." true
# Hi, Adam. This is the message: Mission completed.
./demo-script.sh Adam "Mission completed."
# Flag is not true.

docker cp demo-script.sh jenkins:/tmp/demo-script.sh
# Successfully copied 2.05kB to jenkins:/tmp/demo-script.sh

• Add boolean param

• Update job script

echo "NICKNAME: $NICKNAME"
echo "MSG: $MSG"
echo "FLAG: $FLAG"
/tmp/demo-script.sh $NICKNAME $MSG $FLAG

• Execute

---

API Call

• ref: https://www.jenkins.io/doc/book/using/remote-access-api/
• Job can be invoked by API call
• Common paths:
  • /job/<job_name>/build: build a job
  • /job/<folder>/job/<job_name>/build: with folder
  • /job/<pipeline>/job/<branch>/build: with pipeline and branch

---

Lab: triger a job via API

• Create user: jenkins_trigger
• Create global role: trigger
  • Overall: Read
  • Job: Build, Read
• Assign role
• Login as new user
• Create API token: User profile > Security > API Token > Add new token
• Test: build a job
• enable CSRF protection:
  • Manage Jenkins > Security: CSRF Protection = Crumb Issuer
• Trigger non-parameterized job

# Step 1: Get crumb
CRUMB=$(curl -u jenkins_trigger:<api_token> \
  http://<jenkins_host>/crumbIssuer/api/xml?xpath=concat(//crumbRequestField,":",//crumb))

# Step 2: Use crumb
curl -u jenkins_trigger:<api_token> \
  -H "$CRUMB" \
  -X POST http://<jenkins_host>/job/<job_name>/build?delay=0sec

• Parameterized jobs

curl -u jenkins_trigger:<api_token> \
  -X POST "http://<jenkins_host>/job/<job_name>/buildWithParameters"
  --data param1=value1 --data param2=value2

---