Le lundi 19 février 2018, 09:25:13 CET Adam Sandor a écrit : > Hello Maven people, > > Can someone at least give me some feedback on why this one is not > getting any answers? Asked the question in a wrong way? Is it not > clear? Not interesting? I suppose this is a mix that not many people are fluent with I'll try to help.
> > I think supporting Docker-based builds is very important today. I'm > thinking of contributing code to solve this issue, but I first want to > confirm I didn't miss some solution that is already available. > > Adam > > On Sun, Feb 4, 2018 at 12:57 PM, Adam Sandor > > <adam.san...@container-solutions.com> wrote: > > I’m trying to figure out how to create a two-stage Docker build using > > Maven > > that would properly utilise Docker layer caching. Containing the whole > > build in a Docker container without external dependencies on volume > > mounts (for .m2 cache) has a lot of advantages. > > The only missing piece of the puzzle I can’t figure out is how to force > > Maven to download ALL dependencies just by using the pom file and not > > executing any compilation. The idea behind is to: > > 1. copy the pom file into the image > > 2. use maven to download all dependencies > > 3. copy the sources to the image > > 4. use maven to build the final artifact > > This way Docker will reuse the layer containing the dependencies if the > > pom > > file didn’t change. So dependency caching would be implemented in a > > Docker-ish way that works anywhere the Docker daemon is present as opposed > > to relying on Maven being installed and artifacts getting stored in a > > shared .m2/repository directory. > > > > Now the problem - Maven’s lazy downloading of dependencies. Even if I try > > to execute “mvn dependency:go-offline” Maven still doesn’t download > > plugins and other dependencies, which would only be required during the > > packaging phase. Maven Dependency Plugin is supposed to download plugins: that's surprising you don't get one plugin downloaded. There is one classical cause I imagine: did you define a version for every plugin used? You should be able to have a diagnostic through "mvn versions:display-plugin- updates" Regards, Hervé > > So the following Docker file doesn’t work as intended: > > > > FROM maven AS build > > WORKDIR /build > > ADD pom.xml /build > > RUN mvn dependency:go-offline > > ADD src /build/src > > RUN mvn -o package > > FROM openjdk:8-jdk > > WORKDIR /app > > COPY --from=build /build/target/app.jar /app > > CMD java -jar /app/app.jar > > > > Maven will still start downloading more dependencies on line 6. > > > > I found a workaround for this - execute “mvn package” with a single fake > > main class on line 4, but this is not a nice solution. Can anyone give me > > some option I’m missing or confirm that this is the way things are? In > > that > > case I can go ahead write a blog post showing my workaround to help other > > struggling with the same problem. Thank you! > > > > Adam Sandor from Container Solutions > > > > > > -- > > > > Ádám Sándor > > > > Senior Engineer / Consultant > > > > Container Solutions > > > > 0680126174 > > --------------------------------------------------------------------- > To unsubscribe, e-mail: users-unsubscr...@maven.apache.org > For additional commands, e-mail: users-h...@maven.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@maven.apache.org For additional commands, e-mail: users-h...@maven.apache.org
