spring-boot-cloud-native

Number of ways to create a spring boot container image.

Summary

Method	Layers	Size	Dockerfile
Buildpack	15	261 MB	NA
Jib	8	227 MB	NA
Dockerfile - jdk - fat jar	4	455 MB	rest-server-dockerfile:0.0.1
Dockerfile - jre - fat jar	4	262 MB	rest-server-dockerfile-jre:0.0.1
Dockerfile - jre - multistage	8	262 MB	rest-server-dockerfile-multistage-layered
Dockerfile - jdk - ubi	4	455 MB	rest-server-dockerfile-ubi-openjdk11

Buildpaks

Spring Boot 2.3.0.M1 and above includes buildpack support directly for both Maven and Gradle. Using the buildpack approach, a Dockerfile does not need to be created. The buildpack provides the Java runtime for the application.

Build docker image:

./mvnw spring-boot:build-image

The name of the published image will be your application name and the tag will be the version.

Run the image:

docker run -it -p8080:8080 rest-service:0.0.1-SNAPSHOT

Test the image:

curl http://localhost:8080/greeting

Inspect the image:

dive -j rest-service-buildpack-dive.txt rest-service:0.0.1-SNAPSHOT

Size of image: 261MB

Sources:

• https://spring.io/blog/2020/01/27/creating-docker-images-with-spring-boot-2-3-0-m1
• https://spring.io/guides/topicals/spring-boot-docker/
• https://www.baeldung.com/docker-layers-spring-boot

Jib

Jib builds optimized Docker and OCI images for Java applications with a Docker Daemon.

To use JIB, you need to add a maven plugin:

<plugin>
    <groupId>com.google.cloud.tools</groupId>
    <artifactId>jib-maven-plugin</artifactId>
    <version>2.6.0</version>
</plugin>

Build docker image:

./mvnw compile jib:dockerBuild -Dimage=rest-server-jib:0.0.1

Run the image:

docker run -it -p8080:8080 rest-server-jib:0.0.1

Test the image:

curl http://localhost:8080/greeting

Size of image: 227MB

Source:

• https://github.com/GoogleContainerTools/jib
• https://cloud.google.com/blog/products/application-development/introducing-jib-build-java-docker-images-better

Dockerfile - one stage

This is the traditional approach where a fat jar is built using mvn package that contains all the java artifacts such as application code, spring boot libraries and any dependencies. A Dockerfile needs to be created.

Build docker image:

docker build -t rest-server-dockerfile:0.0.1 .

Run docker image:

docker run -it -p8080:8080 rest-server-dockerfile:0.0.1

Test the image:

curl http://localhost:8080/greeting

Inspect the image:

dive -j rest-server-dockerfile.dive rest-server-dockerfile:0.0.1

Size of image: 455MB

Dockerfile - jre

This is the traditional approach where a fat jar is built using mvn package that contains all the java artifacts such as application code, spring boot libraries and any dependencies. A Dockerfile needs to be created.

Build docker image:

docker build -f Dockerfile.jre -t rest-server-dockerfile-jre:0.0.1 .

Run docker image:

docker run -it -p8080:8080 rest-server-dockerfile-jre:0.0.1

Test the image:

curl http://localhost:8080/greeting

Inspect the image:

dive -j rest-server-dockerfile-jre.dive rest-server-dockerfile-jre:0.0.1

Size of image: 262MB

Dockerfile - multistage layered

To list the java layers to include in the Dockerfille.multistage-layered file run this command:

java -Djarmode=layertools -jar target/rest-service-0.0.1-SNAPSHOT.jar list

Build docker image:

docker build -f Dockerfile.multistage-layered -t rest-server-dockerfile-multistage-layered:0.0.1 .

Run docker image:

docker run -it -p8080:8080 rest-server-dockerfile-multistage-layered:0.0.1

Inspect the image:

dive -j rest-server-dockerfile-multistage-layered.dive rest-server-dockerfile-multistage-layered:0.0.1

Size of image: 262MB

Dockerfile ubi image - one stage

Build docker image:

docker build -f Dockerfile.ubi-openjdk11 -t rest-server-dockerfile-ubi-openjdk11:0.0.1 .

Run docker image:

docker run -it -p8080:8080 rest-server-dockerfile-ubi-openjdk11:0.0.1

Inspect the image:

dive -j rest-server-dockerfile-ubi-openjdk11.dive rest-server-dockerfile-ubi-openjdk11:0.0.1

Size of image: 455MB