Question

I’d like to have a way in which ‘mvn install’ puts files in a repository folder under my source (checkout) root, while using 3rd party dependencies from ~/.m2/repository.

So after ‘mvn install’, the layout is:

/work/project/
    repository
      com/example/foo-1.0.jar
      com/example/bar-1.0.jar
    foo
      src/main/java
    bar
      src/main/java

~/.m2/repository
    log4j/log4j/1.2/log4j-1.2.jar

(In particular, /work/project/repository does not contain log4j)

In essense, I’m looking for a way of creating a composite repository that references other repositories

My intention is to be able to have multiple checkouts of the same source and work on each without overwriting each other in the local repository with ‘install’. Multiple checkouts can be because of working on different branches in cvs/svn but in my case it is due to cloning of the master branch in git (in git, each clone is like a branch). I don’t like the alternatives which are to use a special version/classifier per checkout or to reinstall (rebuild) everything each time I switch.

Answer 1

Maven can search multiple repositories (local, remote, “fake” remote) to resolve dependencies but there is only ONE local repository where artifacts get installed during install. It would be a real nightmare to install artifacts into specific locations and to maintain this list without breaking anything, that would just not work, you don’t want to do this.

But, TBH, I don’t get the point. So, why do you want to do this? There might be alternative and much simpler solutions, like installing your artifacts in the local repository and then copying them under your project root. Why wouldn’t this work? I’d really like to know the final intention though.

UPDATE: Having read the update of the initial question, the only solution I can think of (given that you don’t want to use different versions/tags) would be to use two local repositories and to switch between them (very error prone though).

To do so, either use different user accounts (as the local repository is user specific by default).

Or update your ~/.m2/settings.xml each time you want to switch:

<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0
                      http://maven.apache.org/xsd/settings-1.0.0.xsd">
  <localRepository>${user.home}/.m2/repository</localRepository>
  <!--localRepository>${user.home}/.m2/repository2</localRepository-->
  ...
</settings>

Or have another settings.xml and point on it using the --settings option:

mvn install --settings /path/to/alternate/settings.xml

Or specify the alternate location on the command line using the -Dmaven.repo.local option:

mvn -Dmaven.repo.local=/path/to/repo

These solutions are all error prone as I said and none of them is very satisfying. Even if you might have very good reasons to work on several branches in parallel, your use case (not rebuilding everything) is not very common. Here, using distinct user accounts migh be the less worse solution IMO.