dsh: Docker shell

Run your shell inside docker and take docker with you.

Synopsis

$ sudo ./dsh
Docker image not found. Rebuilding.
Sending build context to Docker daemon 
Step 0 : FROM phusion/baseimage
[...]
Successfully built [...]
# docker ps
CONTAINER ID        IMAGE                       COMMAND                CREATED             STATUS
cdbab3de4ac7        dsh:latest              "/bin/sh -c 'cd /roo   3 seconds ago       Up 2 seconds
# exit
$

What it does

Docker shell (dsh) is a bash shell inside a container, and will bring any docker configuration along, making it possible to control docker from inside dsh.

The shell comes with a data container of its own that is persisted across invocations of dsh. Anything under /root (a symlink to /workspace) is persisted in the data container named dsh-ws.

Any running ssh agent will automatically be available inside dsh.

Parameters

-s|--samba:       start samba server for file sharing
-b|--build:       rebuild dsh image
--host-workspace: to specify a path used as workspace in stead of the
                  normal data container

Any options not on the list above will be passed to docker, for instance:

Use -- to indicate start of command line to run inside dsh:

$ dsh -- ls /
bin   dev  home  lib64	mnt  proc  run	 srv  tmp  var
boot  etc  lib	 media	opt  root  sbin  sys  usr  workspace
$

Examples

Take a peek into a data container

$ sudo ./dsh --volumes-from my-data -- ls
file1 file2 file3

Link a container by name and ping it

$ sudo ./dsh --link my-webserver -- ping my-webserver
PING stashdb (172.17.0.4) 56(84) bytes of data.
64 bytes from stashdb (172.17.0.4): icmp_seq=1 ttl=64 time=0.077 ms

Customizing dsh

Docker shell will create an image named dsh and use it for all invocations of dsh. If you want to customize dsh with extra packages or such, use the image name dsh-custom:

$ sudo ./dsh
# apt-get update && apt-get install some-awesome-package
....
# docker commit $(hostname) dsh-custom

The hostname of the docker shell is the id of the running container, which makes docker commit recognize the currently running container. Next time dsh is run, it will have some-awesome-package installed.

Caveats

Docker shell will try to detect how to connect to the docker daemon on the host, but this may fail. In this case dsh will work as usual, with the exception that the docker command fails. File a bug if this happens!

Docker shell installs a docker client inside dsh that matches the one on the host. If you upgrade your host docker engine, you may need to rebuild dsh (dsh -b). Note that this does not replace dsh-custom. You have to do that yourself if you have any.

Author

Written by Michael Zedeler michael@zedeler.dk

Copyright and license

Copyright Nota (http://nota.dk), licensed under the MIT license, see LICENSE.