Docker Bash Helpers

As I have started to dive into the world of Docker I found myself using a new plethora of commands in my terminal. Thanks to a combination of my terminal multiplexer (tmux), history search (reverse-i-search) and fuzzy finder (fzf) it is relatively easy to retrieve previous commands. When you need to replay a combination of commands this starts to become inefficient. Here is a collection of Bash aliases and functions I use to utilize my daily work with Docker:

Kill all running Docker container

alias docker-killall='docker kill $(docker ps -q)'

Here docker ps lists all running containers where the -q (quiet) option only displays the numeric identifier. With command substituion the results of one command can be passed to the next one. I use this command primarily when I want to make sure that there are no Docker containers left running in the background.

Remove all Docker container

alias docker-rm='docker rm $(docker ps -a -q)'

The -a (all) option displays in addition to running containers also stopped containers.

Remove all Docker images

alias docker-rmi='docker rmi $(docker images -q)'

Sometimes it is also necessary to get rid of all images to start fresh. Here docker images is used to list the images stored in the local Docker repository.

Inspect a running Docker container

With the release of Docker 1.3.0 the command docker exec was added which allows to spawn a process inside a running Docker container and even though I live by the following principle

If you have to ssh into one of your instances your automation has failed.

it is arguable invaluable for development and debugging purposes to create a new Bash session inside a Docker container which can be achieved with the following command:

$ docker exec -it CONTAINER bash

I just found it increasingly annoying to look up the container identifier each time with docker ps and copy-paste it into the command string. In order to automatize this I created a Bash function and alias it:

function find_docker_container() {
  docker ps | grep "$1 " | cut -d ' ' -f1
}

function inspect_docker_container() {
  docker exec -it `find_docker_container $1` bash
}

alias docker-inspect=inspect_docker_container

With grep $1 the container with the name we are looking for is parsed and with cut -d ' ' -f1 the first column (ID) is selected. This makes it nice and easy to quickly jump into one of your containers:

$ docker-inspect redis
root@29892c13c29d:/#

While it is surely fun to create your own aliases to automate tedious tasks it might become problematic when you actually have to use these commands on a remote instance where you cannot import your Bash profile so make sure you understand the underlying commands before seeking comfort.