Docker used to run “out of the box” only on Linux-based systems, but now it is available for
Windows and OS X as well, without
the need for third party tools. This makes it worthwhile to create a quick reference for often used
docker commands and tools. This post is a cheat sheet of commonly used
Docker shell commands. It is meant to serve as a quick reference that you
can consult when developing scripts or debugging. It is not a tutorial - if you haven’t used docker
before please refer to the official learning materials and documentation.
Docker 101 - Managing a Single Container
Inventory of Containers and Images
# Check Docker hub for images with a given name
docker search ubuntu
# Pull a container from Docker hub. To use an image tag - use [image-name]:[tag]
docker pull hello-world
docker pull ubuntu
docker pull ubuntu:12.10
# List all "pulled" images on your local system
# List all running containers
# List all containers (not running as well)
docker ps -a# List what is running in a container. Id/Name is taken from ps.
docker top 32c5a521c664
Start Containers, Run Commands and Shell (SSH-style)
# Start a container - pull it from Docker hub if not present. You can name it.# Standard output/error will be redirected to the current terminal
docker run hello-world
docker run --name=test-container-name hello-world
# Start in detached mode - standard output/error will NOT be redirected to the current terminal
docker run -d hello-world
# Start a container and run a specific command from within
docker run busybox echo"Test\n"
docker run ubuntu /bin/echo hello ubuntu container
run ubuntu /bin/bash -c"ls -l"# Start a container and run a bash sessions interactively (SSH-style)
docker run -it ubuntu bash
docker run -it ubuntu /bin/bash
docker run -it busybox sh
# Attach a shell into a running container (SSH-style). Id/Name is taken from ps.sudo docker exec-it b3a04a93f46f bash
sudo docker exec-it b3a04a93f46f sh
# Detach from a container's shell without killing it (keyboard shortcut):
Ctrl + p + q
# Reattach/reconnect to running shell (if doconnected with the above shortcut)
docker attach 32c5a521c664
# Run an arbitrary command within a running container
docker exec b3a04a93f46f /bin/echo "Hello again"
Networking and Persistent Volumes
# Start a web server in a container; map its port (80) to a localhost port (8080)
docker run -p 8080:80 nginx
# If containers can't access the hosts networking (run on host)
sysctl -w net.ipv4.ip_forward=1
# Force the container to use a specific DNS server
docker run --dns 184.108.40.206 ubuntu
# Mount a host folder '~/test-vol' to a container as '/host-test-vol'
docker run -it-v ~/test-vol:/host-test-vol ubuntu /bin/bash
Restart, Stop, and Delete Containers
# Start/restart a stopped/running container
docker start 33712928d6c5
docker restart 33712928d6c5
# Gracefully stop a running container by.# Sends SIGTERM to the root process.
docker stop b3a04a93f46f
# Forcefully stop a running container (SIGKILL)
docker kill b3a04a93f46f
# Remove a stopped container
docker rm b3a04a93f46f
# Remove a container regardless of its state (i.e. running, stopped)
docker rm -f b3a04a93f46f
Diff a Container and Create an Image
# Check the changes in a container, since it was started from an image
docker diff 60b4f89dfc7f
# Create an image from a container - it will include all new changes
docker commit 60b4f89dfc7f test-image-name
# Define base docker image - will be pulled from the repo if not present
# Metadata - Let people know who build this
MAINTAINER John Dockerson email@example.com
# Install and set-up the current image - run only when creating the image
RUN apt-get update
RUN apt-get install -y git nginx
# Default working directory of all containers from this image
# Set an env. variable 'APP-VER' for all containers from this image
ENV APP-VER 1.0
# Exposes port 80 - only to other containers! Can't be accessed from localhost.
# Mount a volume from the host - less flexible that '-v' option.# Can't specify custom mount point.
# Copy file(s) from the host to the image. If a folder - copies the content!
ADD folder /usr/local/
COPY folder /usr/local/
ADD folder /usr/local/folder
ADD file.txt /usr/local/
# Commands that will run when starting a container - e.g. start web/db server# If the caller passes a command - this will not run! You can have only 1 CMD command.
CMD service nginx start
# Like CMD, but can't be overridden if the caller passes a command!
ENTRYPOINT service nginx start
Working with Dockerfile
# Build a docker image from Dockerfile in the current folder
docker build .# Build a docker image from Dockerfile and name it
docker build -t nikolay/testimage .
docker build -t nikolay/testimage:ver1 .
# Use the latest version of docker composeversion:'2'# Define each container in the services sectionservices:# A container from an existing imagedb:image:postgres# A container from a custom image (defined in Dockerfile)web:# Build the image, map ports, volumes, etc. Specify a commandbuild:.command:python manage.py runserver 0.0.0.0:8000volumes:-.:/codeports:-"8000:8000"depends_on:-db
Run Docker Compose
# From the same folder - start all containers defined in docker-compose.yml.# If some of the containers are running - starts only the needed ones
# Force all containers to be restarted
docker-compose up --force-recreate# Stop all containers