Building docker image for Java Maven Project using CircleCi

Before setup, we need to prepare to login circle with git account.

1. Go Add PROJECTS

2. Chose you desired project and setup or follow project

3. Prepare environment varaible in project setting. The variable are use in config.yml. If you don't want to put credentials info in config.yml, use environment variables. Eg:,

   • CIRCLE_PROJECT_REPONAME : https://hub.docker.com/
   • DOCKER_USER : exampleuser
   • DOCKER_PASS : examplepassword

1. circleci setup in project.

├── app-root
│   ├── .circleci
│   │   ├── config.yml
│   │   ├── setting.xml
│   ├── docker
│   │   ├── app  
│   │   │   ├── .gitkeep
│   │   ├── Dockerfile
│   │   └── wrapper.conf
└── mule-project.xml
└── pom.xml

Here config.yml configuration.

Prepare remote environment to build the project and to create the docker image. As circleci support the docker, build enviroment will be use docker as below. circleci/openjdk:8-jdk image already have maven with java.

version: 2
jobs:
  build:
    docker:
      # specify the version you desire here
      - image: circleci/openjdk:8-jdk  

Prepare working directory and environment

    working_directory: ~/repo

    environment:
      # Customize the JVM maximum heap limit
      MAVEN_OPTS: -Xmx3200m

Checkout git project and build remote environment

    steps:
      - checkout
      - setup_remote_docker

Pull/down and cache the dependencies lib. As there is no cache for firsttime build, it will be download/pull from public repo(Eg, maven-public)

      # Download and cache dependencies
      - restore_cache:
          keys:
          - v1-dependencies-{{ checksum "pom.xml" }}
          # fallback to using the latest cache if no exact match is found
          - v1-dependencies-

If you don't have custom/private repo, you can skip this.

      - run: mvn -s .circleci/settings.xml dependency:go-offline

save dependencies lib as cache. Next time, it will be pull/down the necessary lib.

      - save_cache:
          key: v1-dependencies-{{ checksum "pom.xml" }}
          paths:
            - ~/.m2

Build the project using maven and deploy artifact without snapshots-version, eg, 1.2.3-SNAPSHOT

      - 
        run: "mvn package"
      - 
        store_test_results: 
          path: target/surefire-reports
      - 
        store_artifacts: 
          path: target/<<your-project-name>>-0.0.1-SNAPSHOT.jar
      - 
        run: 
          name: "remove snapshot version"
          command: "if mvn -q -Dexec.executable=\"echo\" -Dexec.args='${project.version}' --non-recursive exec:exec | grep -q \"SNAPSHOT\"; then mvn versions:set -DremoveSnapshot; fi;\n\
              echo $(mvn -q -Dexec.executable=\"echo\" -Dexec.args='${project.version}' --non-recursive exec:exec)-$(echo $CIRCLE_SHA1 | cut -c -7)-$CIRCLE_BUILD_NUM > tempvers.txt\n\
              mvn versions:set -DnewVersion=$(cat tempvers.txt) \n"    

Build docker image according to Dockerfile which is under docker directory.

- 
        run: 
          name: "Build application Docker image"
          command: |
              cp target/*.war docker/app/
              docker login -u $DOCKER_USER -p $DOCKER_PASS
              docker build --no-cache -t $DOCKER_USER/$CIRCLE_PROJECT_REPONAME:$(cat tempvers.txt) docker

Finally, keep and save the created docker image to docker image registory. Example. Docker Hub, JFrog.

              docker push $DOCKER_USER/$CIRCLE_PROJECT_REPONAME:$(cat tempvers.txt)

2. Pull/Setup docker image

FROM tomcat:8.5.35
LABEL maintainer="Zaw Than Oo <zawthanoo.1986@gmail.com>"
COPY ./app/*.war /usr/local/tomcat/webapps

3. Deploy on kubernetes cluster

1. Create registrykey for docker private registery.

kubectl create secret docker-registry XXX_REG_KEY --docker-username=<your-name> --docker-password=<your-pword> --docker-email=<your-email> -n <your-namespace>

2. Create deployment config. Eg. spring-deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: spring-boot-deployment
  labels:
    app: spring-boot
spec:
  replicas: 1
  selector:
    matchLabels:
      app: spring-boot
  template:
    metadata:
      labels:
        app: spring-boot
    spec:
      containers:
      - name: spring-boot
        image: zawthanoo/spring-rest-helloworld:0.1.0-e943d29-21
        ports:
        - containerPort: 8080
      imagePullSecrets:
      - name: XXX_REG_KEY

kubectl create -f spring-deployment.yaml

2. TO export as NodePort, create service config file. Eg: spring-nodeprot.yaml

apiVersion: v1
kind: Service
metadata:
  name: spring-boot-svc
  labels:
    name: spring-boot-svc
spec:
  type: NodePort
  ports:
    - port: 8080
      nodePort: 30180
      name: http
    - port: 443
      nodePort: 31443
      name: https
  selector:
    app: spring-boot

kubectl create -f spring-nodeprot.yaml

Go browser : http://ip-address:30180

If you don't know ip-address, the below command to check node name....

$ kubectl get pods -o wide
$ <NODE_NAME> status