A template project to create a Docker image for a Java application. The example application uses Spring Boot to expose an HTTP endpoint.
Golang developer? Check out https://github.com/miguno/golang-docker-build-tutorial
Features:
- The Docker build uses a
multi-stage build setup
including a downsized JRE (built inside Docker via
jlink) to minimize the size of the generated Docker image, which is 130MB. - Supports Docker BuildKit
- Java 22 (Eclipse Temurin)
- JUnit 5 for testing, Jacoco for code coverage, SpotBugs for static code analysis
- Maven for build management, using Maven Wrapper
- GitHub Actions workflows for Maven and Docker
- Optionally, uses
just
for running common commands conveniently, see justfile.
- Uses .env as central configuration to set variables used by justfile and other helper scripts in this project.
Docker must be installed on your local machine. That's it. You do not need a Java JDK or Maven installed.
Step 1: Create the Docker image according to Dockerfile.
This step uses Maven to build, test, and package the Java application according
to pom.xml. The resulting image is 130MB in size, of which 44MB are
the underlying alpine image.
# ***Creating an image may take a few minutes!***
$ docker build --platform linux/x86_64/v8 -t miguno/java-docker-build-tutorial:latest .
# You can also build with the new BuildKit.
# https://docs.docker.com/build/
$ docker buildx build --platform linux/x86_64/v8 -t miguno/java-docker-build-tutorial:latest .Optionally, you can check the size of the generated Docker image:
$ docker images miguno/java-docker-build-tutorial
REPOSITORY TAG IMAGE ID CREATED SIZE
miguno/java-docker-build-tutorial latest b03be6e7dac4 4 minutes ago 130MBStep 2: Start a container for the Docker image.
$ docker run -p 8123:8123 miguno/java-docker-build-tutorial:latestStep 3: Open another terminal and access the example API endpoint of the running container.
$ curl http://localhost:8123/status
{"status":"idle"}If you have just installed, you can run the commands above more conveniently as per this project's justfile:
$ just
Available recipes:
audit # audit the code
benchmark-plow # benchmark the app's HTTP endpoint with plow (requires https://github.com/six-ddc/plow)
benchmark-wrk # benchmark the app's HTTP endpoint with wrk (requires https://github.com/wg/wrk)
build # alias for 'compile'
clean # clean (remove) the build artifacts
compile # compile the project
coverage # create coverage report
default # print available targets
docker-image-create # create a docker image (requires Docker)
docker-image-run # run the docker image (requires Docker)
docker-image-size # size of the docker image (requires Docker)
docs # generate Java documentation
evaluate # evaluate and print all just variables
format # format sources
format-check # check formatting of sources (without modifying)
infer # static code analysis with infer (requires https://github.com/facebook/infer)
mvnw-upgrade # upgrade mvnw a.k.a. maven wrapper
package # package the application to create an uber jar
pom # print effective pom.xml
run # run the application locally with live reload
run-jar # run the application's packaged jar locally (requires 'package' step)
send-request-to-app # send request to the app's HTTP endpoint (requires Docker and running app container)
site # generate site incl. reports for spotbugs, dependencies, javadocs, licenses
spotbugs # static code analysis with spotbugs
system-info # print system information such as OS and architecture
test # run unit tests
verify # run unit and integration tests, plus coverage check and static code analysisExample:
$ just docker-image-createYou can also build, test, package, and run the Java application locally
(without Docker) if you have JDK 22+ installed. You do not need to have Maven
installed, because this repository contains the
Maven Wrapper mvnw (use mvnw.cmd
on Windows).
# Build, test, package the application locally.
$ ./mvnw clean verify package
# Run the application locally.
$ java -jar target/app.jar
# Alternatively, you can run the application in development mode with hot reloading.
$ ./mvnw quarkus:dev