GNS3 has added docker support in the version 1.5. Since did not deal with docker in the past, I had not found a use-case for docker. Now was the right time to invest some time into docker. Found out there is a interesting article from Jessie Frazelle a former docker employee, she puts every application into a separate docker. Among the applicaton there are irssi, mutt, lynx, tor, chrome, skype etc. She has even routed the chrome docker traffic to the tor docker and now can use chrome with tor. Honestly I do not say this setup is favourable for everyone, but it is good to see what kind of setups are possible with docker containers.

After playing some time with docker I have noticed I want to remove certain docker containers. Up to now there is no easy way to handle this task. There is a stackoverflow question how to do this from CLI. This is how docker looks if listing the repository of availble docker containers

user@host ~ % docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS                    PORTS               NAMES
5ec3bcd3ee3a        centos              "bash"              20 hours ago        Exited (0) 20 hours ago                       small_chandrasekhar
4d0ff619db92        ubuntu              "bash"              20 hours ago        Exited (0) 20 hours ago                       naughty_joliot
efd9b96a0823        ubuntu              "bash"              20 hours ago        Exited (0) 20 hours ago                       backstabbing_jones
7292c2903a3c        hello-world         "/hello"            20 hours ago        Exited (0) 20 hours ago                       boring_thompson

As look at it, you will recognize I have been following the manual to get first experience with docker. There is the hello-world and the ubuntu container. To remove a unused containert I have used following command:

user@host ~ % docker rm $(docker ps -q -f status=exited)
5ec3bcd3ee3a
4d0ff619db92
efd9b96a0823
7292c2903a3c

After that routing all docker container have been removed:

user@host ~ % docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

This is only one of few ways described on how to remove an unused container. Read the article an find out more ways to accomplish this task.

The second difficulty I had to solve was, I needed to deal with the version 0.10 and 0.12 version. Installed docker files on 0.12 and downgraded to 0.10 because needed this to test CORE ''Common Open Research Enviroment'' which still does not work at a gentoo system- Finally after reverting to version 0.12 of docker, the docker service crashed. It did not want to start. No matter what I have done it crashed imidiatelly after a start with a failure message that I do not have now at hand...

However to make a long story short, the solution was to rm the /var/lib/docker directory. It is not a good solution even it is not a solution at all, more a workaround. That saved me a lot of time. Did not have any productive applications anyway. This did cost me around 60 minutes of researching howto solve the problem on a testing platfrom.