Get Bash completion on Docker Mac

I don't know how I've managed without this for so long. Bash completion is a kind of plug-in for your terminal that lets you auto-complete or auto-suggest what to type in next by hitting tab.

Here's the kicker - it works for Docker too after running a few quick scripts.

If you are using a terminal every day then you probably hit tab after every few characters.. like this:

$ docker-com[tab]
docker-compose  
$ 

I use this for laziness, so I get to type less and make fewer mistakes. You also have bash completion for when you're not sure what commands are available.

Do I have bzip? What was it called again?

$ bz[tab]
bzcat         bzdiff        bzfgrep       bzip2         bzless  
bzcmp         bzegrep       bzgrep        bzip2recover  bzmore  

On to Docker

Now if you're running the Docker Mac beta and you have brew installed too, then it only takes a few moments. I learned this information by reading all the way to the bottom of the new Docker for Mac getting started page. This little nugget was hidden away there.

Docker: Installing bash completion

We will run through the instructions here and show a couple of examples of what it looks like when configured.

  • Set up Bash competition through brew
$ brew install bash-completion
$ brew tap homebrew/completions
  • Update your .bashrc or .bash_profile

This snippet will update your .bashrc file that is executed every time you open a terminal.

If you don't have a .bashrc file already then you may want to use chmod +x and to add an extra line at the top of the file #!/bin/bash

cat >> ~/.bashrc <<EOL  
if [ -f $(brew --prefix)/etc/bash_completion ]; then  
. $(brew --prefix)/etc/bash_completion
fi  
EOL  
  • Add Docker-specific completions
cd /usr/local/etc/bash_completion.d  
ln -s /Applications/Docker.app/Contents/Resources/etc/docker.bash-completion  
ln -s /Applications/Docker.app/Contents/Resources/etc/docker-machine.bash-completion  
ln -s /Applications/Docker.app/Contents/Resources/etc/docker-compose.bash-completion  

Profit

Now you can profit from doing things like this:

  • Figuring out commands
$ docker [tab]
attach   events   info     network  rename   service  unpause  
build    exec     inspect  node     restart  start    update  
commit   export   kill     pause    rm       stats    version  
cp       help     load     port     rmi      stop     volume  
create   history  login    ps       run      swarm    wait  
daemon   images   logout   pull     save     tag  
diff     import   logs     push     search   top  

Having done this myself I saw docker top - something brand new for me.

Display the running processes of a container

  • Auto-completing container names

Here I run an nginx container and then forget to give it a name.

$ docker run -d -P nginx
99b9505c7c18e51b1154e7d95f0e034eac4c9264ff2196501208ffd35644c37c  

Commands like docker inspect or docker kill take an ID or name as an input, so if you're new to Docker you would probably copy/paste the whole container ID. Fortunately these commands also work with a few unique characters like below:

99b9505c7c18e51b1154e7d95f0e034eac4c9264ff2196501208ffd35644c37c

$ docker inspect 99b9
$ docker inspect fd3564

For when you want to be explicit about naming then tab-completion helps you out and will attempt to finish off the name or ID you started typing in.

Here I type just the first letter and hit tab. This even works with some of the crazy automatically generated container names that Docker can create.

$ docker inspect 9[tab]
$ docker inspect 99b9505c7c18e51b1154e7d95f0e034eac4c9264ff2196501208ffd35644c37c 

Using names:

$ docker rm -f goof[tab]
$ docker rm -f goofy_curie

So I hope you found this useful - and I'm sure there are lots more ways you can take advantage of this. If you have more hints and hacks for completion let me know in the comments.

See also - swarm mode:

In Docker 1.12RC we get a native, built-in orchestration model called Swarm Mode. Check out my quick tutorials below:

Getting started with Swarm Mode

Alex Ellis

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United Kingdom http://alexellis.io/