With Docker in Docker (DinD), by Jérôme Petazzoni, you can easily emulate a production, multi-container setup in a development environment. At Container Solutions we use Docker in Docker frequently, for example as part of our Mini-Mesos project.
But there was something missing, namely, easy access to the output of inner containers. So to celebrate Amsterdam Gay Pride 2015 we integrated DinD with logspout (an excellent tool by Glider Labs) and gave containers the freedom to speak in all the colors of the rainbow!
Hopefully our pull request will get to mainline (please upvote). For now enjoy our custom 'echte Amsterdamse' distribution!
# run dind
docker run -e LOG=file -d --name mydind --privileged containersol/dind
# start a few noisy containers
for i in {1..20}
docker exec mydind docker run -d alpine sh -c 'while sleep .3; do echo Amsterdam Gay Pride!; done' &
done
# and listen what they have to say!
docker logs -f mydind