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Docker Commands

Introduction

This is a comprehensive cheat sheet of commonly used Docker commands.

Installing Docker

Here are the commands to install Docker on different operating systems:

# Ubuntu/Debian:
sudo apt-get update
sudo apt-get install docker.io

# MacOS (using Homebrew):
brew install docker

# Windows OS (using choco)
choco install docker-desktop

Docker Install Verify

To check if Docker is installed:

which docker

# output
/usr/bin/docker

Check the version installed on your machine:

docker --version

General Commands

Start the Docker daemon:

docker -d

Get help with Docker (can also use --help on all subcommands):

docker --help

Display system-wide information:

docker info

Docker Image

A Docker image is a lightweight, standalone, and executable package that contains everything needed to run a piece of software, including the code, runtime, system tools, libraries, and dependencies..

# List local images
docker images

# Delete an image
docker rmi <image_name>

# Remove all unused images
docker image prune

Docker Build

Build an image from a Dockerfile:

# Build an image from a Dockerfile and tag it with a specified name
docker build -t <image_name> .

# Build an image and tag with naming conventions
docker build -t projectname/domainname/appname:yyyymmdd.sequence .
# Example
docker build -t sample/aspnet-api:20230226.1 .

# Build an image from a Dockerfile without the cache
docker build -t <image_name> . --no-cache

Docker Run

# Create and run a container from an image with a custom name
docker run --name <container_name> <image_name>

# Run a container and publish a container's port(s) to the host
docker run -p <host_port>:<container_port> <image_name>

# Run a container in the background
docker run -d <image_name>

# Remove a stopped container
docker rm <container_name>

# Example with auto-remove and port mapping
docker run --rm -p 8080:80 project1/domain1/app1:20230226.1
  • --rm: Automatically removes the container when it exits. Ensures the container is cleaned up after it finishes running. Useful for temporary or disposable containers.
  • -p 8080:80: Maps the host machine's port 8080 to the container's port 80. Establishes a network connection between the host and container, allowing access to the containerized application via port 8080 on the host.

Exit the container:

exit

Docker Push

# Publish an image to Docker Hub
docker push <username>/<image_name>

Docker container

A Docker container is a lightweight, standalone, and executable runtime instance of a Docker image. It represents a running process that is isolated from the host system and other containers. Docker containers provide a consistent and reproducible environment for running applications. Containers are highly portable and can be easily moved and deployed across different environments, such as development, testing, staging, and production.

Docker Hub

Docker Hub is a cloud-based registry service provided by Docker that allows developers to store and share container images. It serves as a centralized repository for Docker images.

# Login to Docker
docker login -u <username>

# Publish an image to Docker Hub
docker push <username>/<image_name>

# Search Docker Hub for an image
docker search <image_name>

# Pull an image from Docker Hub
docker pull <image_name>

Docker Network

Create a new bridge network named "network1" that containers can connect to for networked communication:

docker network create -d bridge network1

Clean up resources

you can use the docker system prune command to clean up all dangling or unused resources, including images, containers, volumes, and networks that are not tagged or connected to a running container. This command is helpful for freeing up disk space and removing unnecessary resources.

# before cleaning up Docker, first check all the available resources using the following commands:

docker container ls
docker image ls
docker volume ls
docker network ls
docker info

docker system prune
# or
docker system prune -a

If you need to clean up all containers and images locally in Docker Desktop, you can use the following commands:

# To delete all containers including its volumes use,
docker rm -vf $(docker ps -aq)

# To delete all volumes use,
docker volume rm $(docker volume ls -q)

# To delete all the images,
docker rmi -f $(docker images -aq)

Docker Compose Commands

Below are some commonly used Docker Compose commands:

Starts services

docker-compose up

Starts the services defined in your docker-compose.yml file. It creates and starts containers as specified in the configuration.

docker-compose up -d

Starts the services in the background (detached mode).

Stops services

docker-compose down
Stops and removes containers, networks, volumes, and other services defined in your docker-compose.yml file.

docker-compose down -v
Stops and removes containers, networks, volumes, and other services while also removing volumes.

docker-compose down --volumes --rmi all
Stops and removes containers, networks, volumes, and other services, while also removing volumes and images. 

docker-compose stop

Stops the services defined in your docker-compose.yml file without removing them.

Lists the containers

docker-compose ps

Lists the containers that are part of your Docker Compose setup, showing their status.

docker-compose ps -a
Lists all containers, including stopped ones, that are part of your Docker Compose setup.

Displays log

docker-compose logs
Displays log output from services. You can use the -f option to follow the logs in real-time.

docker-compose logs webserver

Displays logs for a specific service.

Executes a command

docker-compose exec webserver ls -l
Executes a command in a running service container.

Builds services

docker-compose build
Builds or rebuilds services defined in your docker-compose.yml file.

Restarts services

docker-compose restart
Restarts services.

Displays configuration

docker-compose config
Validates and displays the configuration of your docker-compose.yml file.

Pauses services

docker-compose pause
Pauses all services. Containers remain running, but they stop processing requests.

docker-compose unpause
Unpauses services after they have been paused.

docker-compose top
Displays the running processes of a service.

Scales service

docker-compose scale webserver=3
Scales a service to the specified number of instances.

Display events

docker-compose events

Streams real-time events from your services.

Docker Compose Config

Parse, resolve and render compose file in canonical format:

docker-compose config

Docker commands Summary

Basic Commands

  • docker run [image]: Start a new container from an image
  • docker ps: List all running containers
  • docker stop [container]: Stop a running container
  • docker rm [container]: Remove a container
  • docker images: List all available images
  • docker pull [image]: Download an image from a registry
  • docker push [image]: Upload an image to a registry
  • docker build [options] [path]: Build an image from a Dockerfile

Advanced Commands

  • docker exec [container] [command]: Run a command inside a running container
  • docker-compose up: Start a Docker Compose application
  • docker network [subcommand]: Manage Docker networks
  • docker volume [subcommand]: Manage Docker volumes
  • docker logs [container]: View the logs of a container
  • docker inspect [container]: Inspect a container
  • docker diff [container]: Show changes to the filesystem of a container
  • docker commit [container] [image]: Create a new image from a container's changes
  • docker save [image]: Save an image to a tar archive
  • docker load: Load an image from a tar archive

References