Dockerize Spring Boot REST API Application

Step-1: Pre-requsites - Create Simple SpringBoot HelloWorld REST API

• Create a simple Helloworld rest api
• In our case, we will downloas this from our course artifacts during project setup.
• Run locally and test
  • Access Helloworld REST API
  • http://localhost:8080/hello
  • http://localhost:8080/hello-bean

{
  "message": "Hello World Bean",
  "appversion": "V1"
}

Step-2: Create Dockerfile

• Create Dockerfile on Application root folder

FROM openjdk:8-jdk-alpine
VOLUME /tmp
EXPOSE 8080
ADD target/*.jar app.jar
ENV JAVA_OPTS=""
ENTRYPOINT [ "sh", "-c", "java $JAVA_OPTS -Djava.security.egd=file:/dev/./urandom -jar /app.jar" ]

Step-3: Update pom.xml with spotify plugin

• Update the pom.xml with Spotify plugin
• For additional reference, please refer below link
• **Important Note: **
  • In the below pom.xml, please ensure we replace "stacksimplify" in repository tag with your docker hub id.
  • stacksimplify/${project.name}
• https://github.com/spotify/dockerfile-maven
• https://mvnrepository.com/artifact/com.spotify/dockerfile-maven-plugin

			<!-- Docker Spotify Plugin -->
			<plugin>
				<groupId>com.spotify</groupId>
				<artifactId>dockerfile-maven-plugin</artifactId>
				<version>1.4.13</version>
				<executions>
					<execution>
						<id>default</id>
						<goals>
							<goal>build</goal>
						</goals>
					</execution>
				</executions>
				<configuration>
					<repository>stacksimplify/${project.name}</repository>
					<tag>${project.version}</tag>
					<skipDockerInfo>true</skipDockerInfo>
				</configuration>
			</plugin>

Step-4: Package as Docker image and Run locally on Docker Desktop.

• Run the below command from application root folder or run the same from Spring Tool Suite IDE

mvn clean package  

• Execute docker commands
  • List docker images
  • Run the docker image locally

docker images
docker run -p 80:8080 stacksimplify/springboot-helloworld-rest-api:1.0.0-RELEASE

• Access Helloworld REST API
  • http://localhost/hello
  • http://localhost/hello-bean

{
  "message": "Hello World Bean",
  "appversion": "V1"
}

Step-5: Push Docker Image to Docker Hub

• Pre-requisites
  • Create an account on docker hub
  • https://hub.docker.com/
• Login to docker hub
• Push the newly created image to docker hub.

docker login
docker push stacksimplify/springboot-helloworld-rest-api:1.0.0-RELEASE
docker push **YOUR DOCKERHUB REPO NAME**/springboot-helloworld-rest-api:1.0.0-RELEASE

• Verify the new repository with 1.0.0-RELEASE tag should be displayed on Docker Hub.

Step-6: Spring Boot - Docker Image Versioning

• Update version tag in pom.xml

	<version>2.0.0-RELEASE</version>

• Package the new image

mvn clean package

• Run the docker image locally (if required to test)

docker images
docker run -p 80:8080 stacksimplify/springboot-helloworld-rest-api:2.0.0-RELEASE

• Push the docker image to Docker Hub

docker push stacksimplify/springboot-helloworld-rest-api:2.0.0-RELEASE

• Verify the same in Docker Hub. New release tag 2.0.0-RELEASE should bedisplayed

Step-7: Run docker image in detached mode

• Run docker image in detached mode (no console output of spring boot application)
• So far we are running in foreground mode where we get the spring boot application console output.

docker run -d -p 80:8080 stacksimplify/springboot-helloworld-rest-api:2.0.0-RELEASE
docker ps

Step-8: Docker Essentinal commands

• The belowa are the list of essential commands we are in need

Commands	Description
docker ps	List all running containers
docker ps -a	List all containers stopped, running
docker stop container-id	Stop the container which is running
docker start container-id	Start the container which is stopped
docker restart container-id	Restart the container which is running
docker port container-id	List port mappings of a specific container
docker rm container-id or name	Remove the stopped container
docker rm -f container-id or name	Remove the running container forcefully
docker pull image-info	Pull the image from docker hub repository
docker pull stacksimplify/springboot-helloworld-rest-api:2.0.0-RELEASE	Pull the image from docker hub repository
docker exec -it container-name /bin/sh	Connect to linux container and execute commands in container
docker rmi image-id	Remove the docker image
docker logout	Logout from docker hub
docker login -u username -p password	Login to docker hub
docker stats	Display a live stream of container(s) resource usage statistics
docker top container-id or name	Display the running processes of a container
docker version	Show the Docker version information

Troubleshooting

• Docker Desktop on mac has an issue with MAC "osxkeychain"
• To fix it perform the below steps.
• Pre-requisite: Refer below link for additional understanding
  • https://medium.com/@dakshika/error-creating-the-docker-image-on-macos-wso2-enterprise-integrator-tooling-dfb5b537b44e
• Step-1: Docker Desktop changes
  • Open Docker Desktop --> Preferences
  • Uncheck the option named Securely store Docker logins in macOS keychain
• Step-2: Go to config.json file in .docker folder
  • Sample Reference Location:
    • /Users//.docker/config.json
    • ~/.docker/config.json
  • Remove the line “credSstore” : “osxkeychain”, in config.json