======Docker======
  * best source of docker wisdom: https://github.com/wsargent/docker-cheat-sheet

===== Building a docker image =====
  - Create Dockerfile or clone docker repository
  - Run:<code>docker build -t YourImage /path/to/dir/with/dockerfile</code>

===== Running docker container =====
<code>docker run -v /srv/elgoog:/mnt -d algoo</code>
  * -d   detached
  * -v   volumes to bind in format /path/at/host:/path/in/container
  * -m  memory limit
  * -c   cpu limit

===== Attach to the running container (docker >= 1.3) =====
<code>docker exec -it <containerIdOrName> bash</code>

===== Attach to the running container (docker < 1.3) =====
  * first discover all running containers on host <code>
docker ps </code>
  * output: <code>
root@xen-docker:~# docker ps
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
d5e31d1cbe9c        algoo:latest        supervisord -n      3 seconds ago       Up 2 seconds        80/tcp              furious_hopper       
ec704ed40100        algoo:latest        supervisord -n      4 seconds ago       Up 3 seconds        80/tcp              distracted_babbage </code>
  * attach to the container  by id (works only if COMMAND = bash)<code>
docker attach d5e31d1cbe9c
</code>
===== Copying files between host and container =====
  * The cleanest way how to copy files between host and container is to mount an image to the container <code>docker run -v /path/to/hostdir:/mnt $container
cp /mnt/sourcefile /path/to/destfile</code>

===== Delete old docker images and keep the running ones =====
  * remove images from docker<code>docker ps -a | grep 'Exited' | awk '{print $1}' | xargs --no-run-if-empty docker rm </code>
  * delete them physically<code>docker images --no-trunc| grep none | awk '{print $3}' | xargs -r docker rmi </code>

====== Docker networking ======
  * http://blog.oddbit.com/2014/08/11/four-ways-to-connect-a-docker/