Spring Boot 3 Deploy on Docker
Spring Boot 3 can be deployed on Docker with a jar file integrated with Dockerfile and docker-compose. The developer can pack a jar file and deploy it on Docker. Docker provides feature deployment through DockerFile and docker-compose, which help developers deploy applications quickly and manage multiple application clusters such as microservices.
The developer can read more about creating a spring boot application. link
In the example, using IntelliJ to create files and manage projects.
IntelliJ provides plugins to support deploying Spring boot applications to docker.
Read more about IntelliJ plugins link
For Docker GUI, using Docker Desktop to manage Docker helps the developer quickly learn about the Docker concept and become familiar with It. Docker Desktop supports OS MacOS, Windows, and Linux.
Read more about and download the Docker desktop. link
Spring boot project directory structure.
/workspaces/demo/
├── src/
│ ├── main/
│ │ ├── java/
│ │ │ └── com/
│ │ │ └── example/
│ │ │ └── demo/
│ │ │ ├── DemoApplication.java
│ │ │ ├── controller/
│ │ │ └── service/
│ │ ├── resources/
│ │ ├── application.properties
│ │ └── static/
│ └── test/
├── target/
├── Dockerfile
├── docker-compose.yml
├── pom.xml
└── README.mdFor example, build a jar file
Execute the command to create a jar file in the directory project.
cd D:\workspaces\demo
mvn clean package -DskipTestsA jar file has been created in the target folder.
For example, create an image from a jar file.
Create the DockerFile name “DockerFile” in the root of the project directory.
The developer can install plugins to support the DockerFile to identify and validate the structure. link
# Use a base image with Java installed
FROM openjdk:21
# Set the working directory in the container
WORKDIR /app
# Copy the JAR file into the container at /app
COPY target/*.jar app.jar
# Specify the command to run your application
CMD ["java", "-jar", "app.jar"]Read more about the OpenJDK tag. link
Execute the command line to create an image on Docker.
docker build -t demo-myapp .Check an image was created.
docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
demo-myapp latest 6f34bf16b0e9 About an hour ago 636MBThe images have been created and are ready to deploy. Execute the command line to deploy the image to the container.
docker run -d -p 8080:8080 --name myapp-container demo-myappThe developer can stop an application via shortcut crtl+c.
Alternatively, The developer can run the docker command for running application in the background process.
docker run -d -p 8080:8080 --name myapp-container demo-myapp -dWhen the developer runs the command in the background process, it closes or exits from the terminal. The application will not stop.
Check the container in which applications are deployed.
docker container ls
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
246b973734dc demo-myapp "java -jar /app.jar" 2 hours ago Up 2 hours 0.0.0.0:8080->8080/tcp myapp_containerThe Docker container shows information about applications in the container.
For example, Create a jar file and an image in a Dockerfile.
The Dockerfile provide a feature to create a jar file from a project using Apache Maven. The developer can build a jar file in Dockerfile.
Read more about Apache Maven. link
Create a Dockerfile with a create a jar file and build an image.
# Stage 1: Build the JAR file
FROM maven:3.9.7-amazoncorretto-21 AS build
WORKDIR /app
COPY pom.xml .
COPY src ./src
RUN mvn clean package -DskipTests
# Stage 2: Run the application
FROM openjdk:21
VOLUME /tmp
EXPOSE 8080
COPY --from=build /app/target/*.jar app.jar
ENTRYPOINT ["java", "-jar", "/app.jar"]Read more about maven tag. link
Execute the command line to create a jar file and then create an image on Docker.
docker build -t demo-myapp .Check an image was created.
docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
demo-myapp latest 344bdb7dd3b4 2 hours ago 636MBthe Docker show information about the image, such as tag, image ID and size.
Execute the command line to deploy the image to the container.
docker run -d -p 8080:8080 --name myapp-container demo-myapp -dCheck the container in which applications are deployed.
docker container ls
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
246b973734dc demo-myapp "java -jar /app.jar" 2 hours ago Up 2 hours 0.0.0.0:8080->8080/tcp myapp_containerThe developer can check an application has started by view logs.
docker logs myapp-containerDeploy Spring boot on Dokcer with docker-compose
Create docker-compose.xml in the directory project.
services:
myapp:
image: myapp:1.0.0
build:
context: .
dockerfile: Dockerfile
container_name: myapp_container
ports:
- "8080:8080"
environment:
SPRING_PROFILES_ACTIVE: docker
SPRING_DATASOURCE_URL: jdbc:postgresql://172.20.0.2:5432/demo
SPRING_DATASOURCE_USERNAME: admin
SPRING_DATASOURCE_PASSWORD: password
networks:
postgres_postgres-network:
ipv4_address: 172.20.0.4
networks:
postgres_postgres-network:
external: trueRead more about docker-compose link
In the docker-compose file, use the postgres_postgres-network networks because the Spring boot application inside Docker must use the same networks to connect to the database.
Read more about creating a database server link
In the environment, the attribute can override config from application.properties.
The developer can control the version of an application by using an “image” attribute <app_name>:<tag_name>
Execute the command line to deploy the Spring boot application to Docker.
docker compose upRead more about docker-compose CLI. link
Check an image was created.
>docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
myapp 1.0.0 223aaea0bcc6 20 minutes ago 636MBCheck the container in which applications are deployed.
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
d84c729e6857 myapp:1.0.0 "java -jar /app.jar" 28 minutes ago Up 28 minutes 0.0.0.0:8080->8080/tcp myapp_containerThe developer can stop the running containers and remove them, along with any networks created by the ‘up’ command.
docker compose downReduce Docker image size
The developer faces the problem of enormous image size. The size of a Docker image from a jar file and JDK. The developer can reduce the size of the Docker image by reducing the size of a jar file and changing OpenJDK.
Reduce the size of a jar by removing unused libraries.
Modifiy Dockerfile for change OpenJDK.
Change from openjdk:21 to amazoncorretto:21-alpine.
# Stage 1: Build the JAR file
FROM maven:3.9.7-amazoncorretto-21 AS build
WORKDIR /app
COPY pom.xml .
COPY src ./src
RUN mvn clean package -DskipTests
# Stage 2: Run the application
FROM amazoncorretto:21-alpine
VOLUME /tmp
EXPOSE 8080
COPY --from=build /app/target/*.jar app.jar
ENTRYPOINT ["java", "-jar", "/app.jar"]Check an image size after changing the OpenJDK.
>docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
myapp 1.0.0 337af59f4fbf 7 minutes ago 449MBThe size of the Docker image was reduced from 636 MB to 449 MB. The developer can find OpenJDK from a link, which JDK is suitable for a project.
Regain disk space from the build cache.
When the developer builds the image multiple times, Docker leaves the build cache and consumes disk space. The developer can remove the build cache for clean Docker disk space.
docker builder pruneor specific time.
docker builder prune --filter=until=24hThe docker will remove the build cache to regain disk space.
>docker builder prune
WARNING! This will remove all dangling build cache. Are you sure you want to continue? [y/N] y
ID RECLAIMABLE SIZE LAST ACCESSED
tu4xgu6uncnf7lic40k1vudsg true 67.48MB 23 minutes ago
zesq2ddqempaztc5v4dmysutt* true 301.5MB 2 days ago
yqism4du5o6aar05qfs6frf56* true 99.63MB 17 minutes ago
1nao14f7mfic6rckq57pekqin* true 99.68MB 15 minutes ago
136upuos04ueg86698onqfz7x* true 98.45MB 18 minutes ago
1r6c6m5fi20dgwwhtxujpat9b true 131.8MB 2 days ago
vkmh4r9kr6uy9giqqu646a556* true 301.5MB 9 minutes ago
7t0xioew522nkpan7o7rbe3w2* true 96.63MB 20 minutes ago
41lk2v46fkdilxzcptnt68mr7 true 99.63MB 17 minutes ago
pujsd6l5s7b47crgdogw8sc9i true 98.45MB 18 minutes ago
7ake92a5q8ccrl0ugkzj2egno true 131.8MB 2 days ago
ie3t256s7ipvjliwcekb5rzj5 true 131.8MB 9 minutes ago
fanmm3qv2td7iin35es3dyj8w true 95.49MB 21 minutes ago
qaahv3dusdm5vyrt1hwchm8nz* true 67.48MB 23 minutes ago
r3iesxlco2iax1q04pm09n6xe true 96.63MB 20 minutes ago
36d9q7yhqoa7308f7z8e0psg6 true 117.9kB Less than a second ago
mapvhmejjxmfnbpelon93oo2p true 117.9kB 2 hours ago
wgklx2mlwhb446jy9oa6pndwt true 131.8MB 2 hours ago
ktkjpo4qlzclk62h3jado4k7c* true 0B 9 minutes ago
xht8tgnck2jr2pwgib2csunfs true 131.8MB 47 minutes ago
gh27uf7lzyxygjtmkl36zyy90 true 0B 47 minutes ago
ofd75ozsowyrg53rsgn638x2q* true 301.5MB 2 days ago
zq13t0q4qqndhszo1kdrs4gmh* true 318B 9 minutes ago
jv877s2g4oojx75hgxz2si19m* true 124.1kB 9 minutes ago
4od7l5iq5zqyx2edrys9a3p06 true 99.67MB 15 minutes ago
24t28fyhbjkgqvbo23bpisc5m* true 95.49MB 21 minutes ago
v17p3e7yx8xq14xfst2pl1o19 true 131.8MB 15 minutes ago
q4ctv7065iycz8g6xm2t9n5e1 true 0B 47 minutes ago
c9jl3hd0fa3i2nz46b98k8pxf true 0B Less than a second ago
540kiz4ttwocoj7l5fhn3bw84 true 117.8kB Less than a second ago
m4kf1nvaqeygcjm6k8wb6tndc true 0B Less than a second ago
td05cq5mgzl1awbh2urlwcp0m true 6.319kB Less than a second ago
vnao9xckt7jty3rpcp73x7s9q true 0B 23 minutes ago
ar41xz1odrpeh0313j4o3z9fc true 0B Less than a second ago
z3s9jy3aj4xj43q2bvwnw81ol true 0B 9 minutes ago
piul44hdxunnjo5lwdxjl3ki0 true 0B Less than a second ago
lilk5cwngipo0hl038xuhmzr5 true 0B Less than a second ago
i2rz2rdxix3dwqambmuiqlw2u true 0B 23 minutes ago
rw5y19yqqniqzn733bkif7taa true 0B Less than a second ago
qllnpgsz47ozsnjhdn2geil5r true 0B 23 minutes ago
f6ah0lfwwuql235byxze728qr true 0B Less than a second ago
w8vfc9pedlfmvn6gh0bxp7rza true 0B Less than a second ago
69427u9yuc1x3nettgrhpz622 true 0B Less than a second ago
jywrb9h68niooq37oisxzynzv true 0B Less than a second ago
9njysdc8ultvus3f1s03s1wqn true 0B Less than a second ago
Total: 2.811GBFinally, Docker helps the developer easily manage and deploy the application. It provides various features for managing Docker.
The developer should learn Docker to communicate with devOps and design the software architecture's CI/CD pipeline. The developer can use Docker integrated with Docker Swarm or Kubernetes to enhance the deployment, management, and scalability of containerized applications.
Thanks for reading.