How to persist changes made by maven dependency:go-offline in docker image

Question

I'm Test Automation engineer and working in big product company. Companies big monolithic project being divided and parts are departuring into clouds. As part of such redesign Test Automation projects should also get cloudy. Our typical TA project based on groovy, selenium, testng and maven. Now I want to try the option of putting whole TA maven project into Docker image\container. Its works well, but on the very first run it starts download dependencies into local .m2 repository. I want to speed up and have this task done on a creation image stage.

Here is a my DOCKERFILE:

FROM maven:3.3-jdk-8
LABEL description="Embedded portal-web-testing"
MAINTAINER NNN
COPY ./settings.xml  /root/.m2/
COPY ./acceptance-tests  ./acceptance-tests
WORKDIR acceptance-tests
RUN mvn dependency:go-offline --debug >log
RUN ls /root/.m2/
#RUN mvn test
ENTRYPOINT ["bash"]

And here is a log:

Step 1 : FROM maven:3.3-jdk-8
 ---> 7addddbdd730
Step 2 : LABEL description "Embedded portal-web-testing"
 ---> Running in 1d195ccb9c57
 ---> f5372b024ca0
Removing intermediate container 1d195ccb9c57
Step 3 : MAINTAINER NNN
 ---> Running in 03ebbffda680
 ---> cb12da3d8ec6
Removing intermediate container 03ebbffda680
Step 4 : COPY ./settings.xml /root/.m2/
 ---> 164999e1f63a
Removing intermediate container 1e1778d2533b
Step 5 : COPY ./acceptance-tests ./acceptance-tests
 ---> 7d93fff4193e
Removing intermediate container a5d04eb30591
Step 6 : WORKDIR acceptance-tests
 ---> Running in f15111475fc6
 ---> beb4d090362b
Removing intermediate container f15111475fc6
Step 7 : RUN mvn dependency:go-offline --debug >log
 ---> Running in 2c09f1869143
 ---> 62326c2bb073
Removing intermediate container 2c09f1869143
Step 8 : RUN ls /root/.m2/
 ---> Running in 91b602f529da
settings.xml
 ---> b7bc32199ab3
Removing intermediate container 91b602f529da
Step 9 : ENTRYPOINT bash
 ---> Running in 3167f5a6d923
 ---> 94b3e0b146da
Removing intermediate container 3167f5a6d923
Successfully built 94b3e0b146da

On Step 7 surely files being downloaded, but looks like not stored. Following console command shows that there are no updates in local .m2 folder:

root@37f5a0d04232:/acceptance-tests# ls /root/.m2
settings.xml

If I try to run same command again from command line inside a container (when image is created and container had started):

root@37f5a0d04232:/acceptance-tests# mvn dependency:go-offline

Massive downloads starts and repository folder finally appeared under .m2

root@37f5a0d04232:/acceptance-tests# ls /root/.m2
repository  settings.xml

I struggle to understand why changes caused by maven command from Dockerbuild file did not stored as docker layer.

I am using Docker 1.12 and maven 3.3.3

Qasim Sarfraz · Answer 1 · 2017-03-28T18:48:43.610

/root/.m2 is a volume that is why it gets cleared when docker container is launched. This can be avoided by caching the content in a custom directory and then copying it to /root/.m2 when container is launched.

Fortunately maven image is pre-baked with all the copying logic so you just have to point repository as:

RUN mvn -B -f /tmp/pom.xml -s /usr/share/maven/ref/settings-docker.xml dependency:resolve

The entry-point will take care of setting local repository for you. It helped me hope it helps you as well.

Also, for reference visit.

How to persist changes made by maven dependency:go-offline in docker image

1 Answers1