Usually, there’s no change in
pom.xml file but just some other source code changes when you’re attempting to start docker image build. In such circumstance you can do this:
FROM maven:3-jdk-8 ENV HOME=/home/usr/app RUN mkdir -p $HOME WORKDIR $HOME # 1. add pom.xml only here ADD pom.xml $HOME # 2. start downloading dependencies RUN ["/usr/local/bin/mvn-entrypoint.sh", "mvn", "verify", "clean", "--fail-never"] # 3. add all source code and start compiling ADD . $HOME RUN ["mvn", "package"] EXPOSE 8005 CMD ["java", "-jar", "./target/dist.jar"]
So the key is:
mvn verify --fail-neverit, it will download maven dependencies.
add all your source file then, and start your compilation(
When there are changes in your
pom.xml file or you are running this script for the first time, docker will do 1 -> 2 -> 3. When there are no changes in
pom.xml file, docker will skip step 1、2 and do 3 directly.
This simple trick can be used in many other package management circumstances(gradle、yarn、npm、pip).
You should also consider using
mvn dependency:resolve or
mvn dependency:go-offline accordingly as other comments & answers suggest.