MY Docker Cheat Sheet

a breif selection of essential commands, tips and notes about working with docker, as a personal reference. use at your own risk.

Working with containers

create and start a container

• docker run [-a] <container-name> <override>

essentially runs the following two commands

• docker create <container-name> <override>
• docker start [-a] <container-id>

list all running containers

• docker ps

list all containers

• docker ps --all

delete everything

• docker system prune

output logs for a running container

• docker logs <container-id>

gracefully stop a running container

• docker stop <container-id>

forcefully, and immediately, stop a container

• docker kill <container-id>

run a command in a running contianer (optionally interactive)

• docker exec [-it] <container-id> <command>

Exiting an interactive session can usually be accomplished cmd+c will exit, if not try ctrl+d, or simply type exit

Dockerfile

• FROM : specifty a base image to start from
• LABEL : add arbitrary labels, such as author with author=<you-name>
• WORKDIR : specify a working directory in the container (all commands after, use this as root)
• COPY : copy somePath into the container working directory
• RUN : run arbitrary commands
• CMD : set an initial start command for when your container builds

Here is an example Dockerfile

# use a base image
FROM alpine

# dl and install deps
RUN apk add --update redis

# tell it what to do when it starts
CMD ["redis-server"]

this is a very basic container, here's another, thats slightly more complete:

FROM node:alpine
LABEL author="my-docker-id"

WORKDIR /usr/app

COPY ./package.json ./
RUN npm install
COPY ./ ./

CMD ['npm', 'start']

as each instruction is cached, the order is important, to avoid unneccessary rebuild steps and cache busting.

Building containers

after creating your Dockerfile run the following in your project dir:

• docker build -t <username/name> .

not that this will name your build with the <username/name> . . then run the following to start that container, notice we're parsing in the -p flag to specify the port, and are able to run the container by name, rather than id.

• docker run -p <external-port>:<container-port> <container-id or name>