mvnw with sub-modules

[ksperling]

As @dsyer mentioned in #4 mvnw doesn't play well with sub-modules.

I'm currently using this little helper script, a copy of which I drop into every sub-module. It traverses up the directories to find the root project (a directory that contains pom.xml, mvnw, and .mvn/wrapper). It then runs the top level mvnw, passing the sub-module it was executed from and --also-make (to build dependencies as well).

As workarounds go this has been working well for me for the last 10 months or so, but it would be neat if mvnw supported this out of the box.

In it's simplest form "support" could mean mvnw ships this script and provides a way to drop a copy into a sub-module on request (having the script in each module is quite nice in that you can always say ./mvnw ... rather than having to supply the right number of ../....

Alternatively some of this logic could be integrated into mvnw directly so that when run from a sub-directory the relevant maven arguments are injected automatically. The per-module mvnw script could then potentially be replaced with a symlink.

#!/bin/bash
# child-mvnw: Finds the top-level project and invokes a reactor build there

path=""; cd "$(dirname "$0")"
while true; do
  if [ "$PWD" = "/" ]; then echo "Unable to find project root" >&2; exit 1; fi
  path="$(basename "$PWD")/$path"; cd ..
  [ -f pom.xml -a -f mvnw -a -d .mvn/wrapper ] && break
done
exec ./mvnw --projects "${path%/}" --also-make "$@"

If there's interest in this I'd be happy to provide a pull request (for non-Windows platforms at least, don't have a Windows machine on hand to test with), but I wanted to see if anybody else cares about this feature and/or other ideas to approach it.

[dsyer]

What I do is create a bash alias/function that does the same thing. You can't really integrate this into mvnw because it won't be on the PATH. The whole point of the wrapper is that it is self-contained. Here's my alias in case anyone else wants to use it:

function mvn {
         dir=`pwd`
         while [ -e $dir/pom.xml ] && ! [ -e $dir/mvnw ] && ! [ -z $dir ]; do dir=${dir%/*}; done
         if [ -e $dir/mvnw ]; then
              echo "Running wrapper at $dir"
              $dir/mvnw $@
              return $?
         fi
         echo No wrapper found, running native Maven
         `which mvn` $@
}

I put that in my .bashrc (and a similar one for gradle).

[ksperling]

Thanks, that's a neat way of switching between mvnw and stand-alone mvn.

The feature of my script that I was wondering if mvnw could support directly is running mvn with --projects pointed to the current sub-module (i.e. it actually runs a reactor build on the top-level project, but limited to the current module and it's dependencies).

I suppose I would have the same problem with standalone mvn rather than mvnw, so maybe it's not a feature that mvnw should provide directly.

[mosabua]

Not really a mvnw problem as stated in the comments above.