Jenkins continuous deployment demo with Spring Boot

This is a demo application to show how to set up continuous deployment for a Spring Boot application via Jenkins. All values in square brackets below are placeholder values that should be replaced by the user.

This setup requires the manual creation of a database and database user on the application server.

The following shell script will also need to be created and saved as [APPLICATION_NAME].sh in /usr/local/bin/ on the application server:

#!/bin/sh
SERVICE_NAME=[APPLICATION_NAME]
PATH_TO_JAR=/apps/[APPLICATION_NAME].jar
PID_PATH_NAME=/tmp/[APPLICATION_NAME]-pid
LOG_FILE=/tmp/[APPLICATION_NAME].log
case $1 in
    start)
        echo "Starting $SERVICE_NAME ..."
        if [ ! -f $PID_PATH_NAME ]; then                    # Ignore the square brackets in this line
            nohup java -Dspring.profiles.active=prod -jar $PATH_TO_JAR /tmp 2>> $LOG_FILE >> $LOG_FILE &
                        echo $! > $PID_PATH_NAME
            echo "$SERVICE_NAME started ..."
        else
            echo "$SERVICE_NAME is already running ..."
        fi
    ;;
    stop)
        if [ -f $PID_PATH_NAME ]; then                      # Ignore the square brackets in this line
            PID=$(cat $PID_PATH_NAME);
            echo "$SERVICE_NAME stoping ..."
            kill $PID;
            echo "$SERVICE_NAME stopped ..."
            rm $PID_PATH_NAME
        else
            echo "$SERVICE_NAME is not running ..."
        fi
    ;;
    restart)
        if [ -f $PID_PATH_NAME ]; then                      # Ignore the square brackets in this line
            PID=$(cat $PID_PATH_NAME);
            echo "$SERVICE_NAME stopping ...";
            kill $PID;
            echo "$SERVICE_NAME stopped ...";
            rm $PID_PATH_NAME
        fi

        echo "$SERVICE_NAME starting ..."
        nohup java -Dspring.profiles.active=prod -jar $PATH_TO_JAR /tmp 2>> $LOG_FILE >> $LOG_FILE &
        echo $! > $PID_PATH_NAME
        echo "$SERVICE_NAME started ..."
    ;;
esac

Remember to run chmod +x [APPLICATION_NAME].sh to grant execution privileges.

Jenkins basics for maven-based deployments via Git

For this method of deployment to work, Jenkins should have the Git plugin installed.

Select Create new item from the left-hand menu of the Jenkins dashboard, enter your application name and select Maven project to continue.

Jenkins source code management steps

Under the header Source Code Management, enter the URL of your git repository. Decide if you would like to deploy from master or other branches in your repo.

Jenkins build triggers

Check Build whenever a SNAPSHOT dependency is built.

Check Poll SCM and enter * * * * * under Schedule. This tells Jenkins to check for updates to the chosen git branch(es) every minute. You can find out more about scheduling tasks at specific time intervals in the documentation for the Linux cron system.

Jenkins pre-build steps

Add the following shell command as a pre-build step:

echo "spring:
  jpa:
    show-sql: false
    hibernate:
      ddl-auto: update
  datasource:
    url: jdbc:mysql://localhost:3306/[DATABASE]
    username: [DATABASE_USERNAME]
    password: [DATABASE_PASSWORD]
server:
  port: [PORT]" > $WORKSPACE/src/main/resources/application-prod.yml;
  
  cp $WORKSPACE/src/main/resources/application-prod.yml $WORKSPACE/src/main/resources/application.yml

Jenkins build steps

Add package to the Goals and Options field.

Jenkins post-build steps

Add the following shell command as a post-build step:

cp target/[APPLICATION_NAME_STUB]*.jar /apps/[APPLICATION_NAME].jar
daemonize -E BUILD_ID=[APPLICATION_NAME]_${BUILD_NUMBER} /usr/local/bin/[APPLICATION_NAME].sh restart

Select Run only if build succeeds to ensure your application keeps running even when new builds fail.

wallabythree / jenkins-demo