Set auto build system in Docker Spring boot container

Hi, I’m Lovefield.

I wrote about how to use docker-compose to raise Spring boot the other day. Implementing and managing a microservice environment with Docker is a good thing, but for apps that require build, there is a pretty cumbersome process.You need to update the resources, build, and then restart the container. In the case of the build tool of Spring boot, if it is not cached, it will start downloading all modules. Caching is not possible due to the nature of the Docker that deletes and reconfigures the container.

So, You want to configure an environment that automatically builds and restarts spring boot containers using Docker volumes and Git hook file.

First, write the docker-compose.yml file.

…
spring:
       container_name: appname
       image: openjdk:11.0.7-jdk-slim
       volumes:
           - ./appname:/spring
           - ~/.gradle:/root/.gradle:rw # cache folder
       working_dir: /spring
       command: java -jar ./build/libs/appname-0.0.1-SNAPSHOT.jar
…

Using image openjdk:11.0.7-jdk-slim. What's important here is that you have to use “jdk” to have a tool for building. If you use “jre” for execution, the build will not run, so please be careful. Use the slim version to reduce image capacity.

In Mac ~/.gradle is the space where the cache used by Gradle when building is stored. And the container's /root/.gradle is where Gradle finds the cache when executing a command inside the container. It synchronizes caching data locally with the container.

The container is now synchronized with the Gradle cache with the local environment. When using pull and checkout with Git, I plan to build in the container and restart the container so that the change can be applied.

Create files post-checkout and post-merge of Git hook. The default Git hook path is .git/hooks. Write the following commands in each file:

docker exec appname ./gradlew build -x test && docker-compose restart spring

All settings are now complete. If you use pull or checkout in the spring repo, you can see the build and restart.