Spring PetClinic Sample Application

Understanding the Spring Petclinic application with a few diagrams

See the presentation here

Running petclinic locally using source code

Petclinic is a Spring Boot application built using Maven. You can build a jar file and run it from the command line (it should work just as well with Java 8, 11 or 17):

Running petclinic locally as docker container

Docker Hub Location for container images

https://hub.docker.com/repository/docker/devstartshop/spring-petclinic

Find tagname from this location and use it with below command to run the petclinic application as docker container

docker run -p8080:8080 devstartshop/spring-petclinic:<tagname>

You can then access petclinic here: http://localhost:8080/

Deployment Process

The project contains 2 files important for deployment

1. Dockerfile - used to build a docker image using the app.jar file that gets generated in target/ folder when application is build using maven build tool. the container is set to run with a non root user 1001 and exposes port 8080
2. Jenkinsfile - used to declare step-by-step stages to checkout, compile, test, build and publish the application. The Declarative pipeline defined in Jenkinsfile has some prerequisites to run successfully on the Jenkins server.

I have used a Jenkins DIND setup using a docker compose file. this runs Jenkins server as a docker container and enables us to run docker commands from within the container to build the application docker image.

I have configured below tools in Jenkins Global Tool Configuration:

1. All defaults plugins
2. Managed File plugin to define custom Maven settings.xml file that helps to resolve maven dependencies from JFrog Artifactory (JCenter Remote)
3. Maven Pipeline plugin for withMaven DSL commands
4. Docker pipeline plugin for withDockerRegistry DSL command.
5. JAVA 11
6. MAVEN 3.8.4
7. Credentials (Personal Access Token) for repository on the guthub.com to push code.

Additional Setup required for Executing Jenkins pipeline

Run Jenkins in a docker container with docker-dind as sidecar and then configure environment variables in jenkins to point to docker host in dind container. Files used:

1. Dockerfile
2. docker-compose.yaml Make sure both files a in the same directory and docker is running and docker-compose command is available.

Files used:

1. Dockerfile

FROM jenkins/jenkins:lts-jdk11
USER root
RUN apt-get update && apt-get install -y apt-transport-https \
       ca-certificates curl gnupg2 \
       software-properties-common
RUN curl -fsSL https://download.docker.com/linux/debian/gpg | apt-key add -
RUN apt-key fingerprint 0EBFCD88
RUN add-apt-repository \
       "deb [arch=amd64] https://download.docker.com/linux/debian \
       $(lsb_release -cs) stable"
RUN apt-get update && apt-get install -y docker-ce-cli

2. docker-compose.yaml

version: "3.7"

services:
  docker:
    image: docker:dind
    privileged: true
    ports:
      - "2376:2376"
    environment:
      - DOCKER_TLS_CERTDIR=/certs
    networks:
      - jenkins
    volumes:
      - jenkins-docker-certs:/certs/client
      - jenkins-data:/var/jenkins_home

  jenkins:
    build:
      dockerfile: ./Dockerfile
      context: ./
    networks:
      - jenkins
    environment:
      - DOCKER_HOST=tcp://docker:2376
      - DOCKER_CERT_PATH=/certs/client
      - DOCKER_TLS_VERIFY=1
    volumes:
      - jenkins-data:/var/jenkins_home
      - jenkins-docker-certs:/certs/client:ro
    ports:
      - "8080:8080"
      - "50000:50000"
    dns: ["8.8.8.8"]

networks:
  jenkins: { }

volumes:
  jenkins-docker-certs: { }
  jenkins-data: { }

Run below command to start the Jenkins server

docker-compose up

Follow the steps as guided by jenkins to complete the setup.

Once Jenkins server is up and running, install the Tools and Plugins mentioned above.

Steps to create a pipeline in Jenkins server

1. Add Docker registry credentials to credentials store using the credentialsId used in the declarative pipeline (Jenkinsfile)
2. Create New Item > Pipeline
3. Add Pipeline configuration as per below screenshot and click save.:
4. 

A Glance at Jenkins Stages:

Run Tests Report

Once the Jenkins build completes, we can see the test report generated by maven surefire plugin. Below screenshot shows Maven Test run report.