Docker CLI Tips and Tricks

docker-cli-tips-and-tricks.md

Docker Cli Tips and Tricks

• bret@bretfisher.com
• https://twitter.com/BretFisher
• http://bretfisher.com

My favorite command line options and best practices

• Bash/zsh completion
  • use Tab to populate command line, narrows down options as you go, fills in container names, ID's, images, volumes. Huge time saver.
  • http://blog.alexellis.io/docker-mac-bash-completion/
  • https://github.com/docker/docker/blob/master/contrib/completion/bash/docker
  • https://docs.docker.com/compose/completion/
• Even without auto complete: you don't need type full container ID's
  • just type enough of ID to be unique
  • Example: docker rmi 7c9 2f 5cad will remove three images
• Name volumes to find/keep easier
  • Example: docker run --name psql -d -p 5432:5432 -v psql:/var/lib/postgresql sameersbn/postgresql
  • Then: docker volume ls
• Use ONBUILD Versions for easy development of Node, Ruby, and others
  • https://docs.docker.com/engine/userguide/eng-image/dockerfile_best-practices/#/onbuild
  • https://hub.docker.com/_/ruby/
  • https://hub.docker.com/_/node/
• Always use docker-compose down to cleanup properly (networks, containers)
  • To also remove unnamed containers and volumes: docker-compose down -v --rmi local

My favorite command line aliases (quick container management, usually for local dev)

• Only removes stopped containers, doesn't delete data volumes, mostly safe
  • alias drma='docker rm $(docker ps -aq)'
• Remove all images, doesn't remove images in use by containers, mostly safe
  • alias drmi='docker rmi $(docker images -q -f "dangling=true")'
• Remove all images, doesn't remove images in use by containers, mostly safe
  • alias drmai='docker rmi $(docker images -q)'
• For Docker Machine users, set docker cli to use the default VM
  • alias drdefault='eval "$(docker-machine env default)"'
• Execute interactive command in running container
  • alias drit='docker exec -it'
• Get the IP for eth0 inside the container
  • alias drip='docker inspect --format="{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}"'

Other lists/dotfiles/functions for less typing

• oh-my-zsh has a add-in, which I use always
• jessfraz has some next level shit as bash functions
• @tcnksm has a good list to start with

Cli filters for managing lots of images/containers

Filters

• Filtering the image list
  • Only list dangling images (built with no name): docker images --filter "dangling=true"
• Filtering the containers list
  • Only list containers that have exited successfully (without error): docker ps -a --filter 'exited=0'
  • Only list containers coming from nginx image: docker ps --filter ancestor=nginx

Formatting

• Change the columns shown in docker command, great for TPS Reports
• docker images --format "table {{.ID}}\t{{.Repository}}\t{{.Tag}}" > images.txt

Best list of all things Docker ecosystem

• https://github.com/veggiemonk/awesome-docker