Docker cache gradle dependencies

Question

I\'m trying to deploy our java web application to aws elastic beanstalk using docker, the idea is to be able to run the container locally for development and testing and eve

Answer 1

You might want to consider splitting your application image to two images: one for building the myapp.war and the other for running your application. That way, you can use docker volumes during the actual build and bind the host's ~/.gradle folder into the container performing the build. Instead of only one step to run your application, you would have more steps, though. Example:

builder image

FROM 

# Add project Source
# -> you can use a project specific gradle.properties in your project root
# in order to override global/user gradle.properties
ADD . /var/app/myapp

RUN mkdir -p /root/.gradle
ENV HOME /root
# declare shared volume path
VOLUME /root/.gradle
WORKDIR /var/app/myapp/ 

# Compile only
CMD ["./gradlew", "war"]

application image

FROM 

ADD ./ROOT.war /opt/tomcat/webapps/ROOT.war

# Start Tomcat
CMD ["/opt/tomcat/bin/catalina.sh", "run"]

How to use in your project root, assuming the builder Dockerfile is located there and the application Dockerfile is located at the webapp subfolder (or any other path you prefer):

$ docker build -t builder .
$ docker run --name=build-result -v ~/.gradle/:/root/.gradle/ builder
$ docker cp build-result:/var/app/myapp/myapp.war webapp/ROOT.war
$ cd webapp
$ docker build -t application .
$ docker run -d -P application

I haven't tested the shown code, but I hope you get the idea. The example might even be improved by using data volumes for the .gradle/ cache, see the Docker user guide for details.