To build for Android (from the root of the rr source tree):
docker build .android -t rr-android mkdir -p obj/dist docker run -it --rm \ -u $UID:$GID \ -v $(pwd):/src/rr \ -v $(pwd)/obj/dist:/dist \ rr-android
-u $UID:GID
ensures that the build runs with your current UID/GID, which is necessary to avoid the output being only writable by root.
-v $(pwd):/src/rr
mounts the source tree in the container so it can be built.
-v $(pwd)/obj/dist:/dist
sets the output directory for the container to the current directory. The last step of the build will copy the rr tarball to the directory on the left of :
.