Docker Cheat Sheet

Dockerfile

A Dockerfile is a script used to build Docker images. It consists of a series of commands:

FROM

FROM image_name:tag

Description: Specifies the base image used to build the new image.

RUN

RUN command

Description: Executes a command in the new image's filesystem during the build process.

CMD

CMD command

Description: Specifies the default command to run when a container is launched from the image.

WORKDIR

WORKDIR /path/to/directory

Description: Sets the working directory for subsequent instructions.

COPY

COPY source destination

Description: Copies files or directories from the host system into the image.

ADD

ADD source destination

Description: Similar to COPY, but can also extract tarballs or fetch URLs.

EXPOSE

EXPOSE port

Description: Informs Docker that the container listens on specific network ports at runtime.

ENV

ENV key=value

Description: Sets environment variables in the image.

ENTRYPOINT

ENTRYPOINT command

Description: Configures the container to run as an executable.

ARG

ARG variable_name

Description: Defines a variable that users can pass at build-time to the builder with the docker build command.

USER

USER username

Description: Sets the user the application will run as within the container.

Docker Registry

Login to a Docker registry:

docker login

Description: Logs in to a Docker registry interactively.

Logout from a Docker registry:

docker logout

Description: Logs out from a Docker registry.

Build an image from a Dockerfile:

docker build -t image_name .

Description: Builds a Docker image from a Dockerfile in the current directory.

Push an image to a Docker registry:

docker push image_name

Description: Pushes a Docker image to a Docker registry.

Docker Containers

Run a container interactively:

docker run -it image_name

Description: Starts a new container interactively using the specified image.

Run a detached container:

docker run -d image_name

Description: Starts a new container in detached mode (background).

Run a container with a custom name:

docker run --name custom_name image_name

Description: Starts a new container with a specific name.

Run a container with environment variables:

docker run -e "VAR=value" image_name

Description: Sets environment variables in the container.

Run a container and map ports:

docker run -p host_port:container_port image_name

Description: Maps a container port to a host port.

Run a container and mount a volume:

docker run -v /host/path:/container/path image_name

Description: Mounts a host directory into the container.

Stop a running container:

docker stop container_id

Description: Stops a running container.

Start a stopped container:

docker start container_id

Description: Starts a stopped container.

Pause a running container:

docker pause container_id

Description: Pauses the execution of a container.

Unpause a paused container:

docker unpause container_id

Description: Resumes a paused container.

Restart a container:

docker restart container_id

Description: Restarts a running or stopped container.

Attach to a running container:

docker exec -it container_id /bin/bash

Description: Attaches to a running container and opens a shell.

Remove a stopped container:

docker rm container_id

Description: Deletes a stopped container.

Remove a running container:

docker rm -f container_id

Description: Forces removal of a running container.

Show container resource usage:

docker stats container_id

Description: Displays live resource usage statistics of a container.

Show container logs:

docker logs container_id

Description: Displays logs from a container.

Copy files from/to a container:

docker cp /local/path container_id:/container/path

Description: Copies files between a container and the local filesystem.

Inspect a container:

docker inspect container_id

Description: Shows detailed information about a container.

Create a container without starting it:

docker create image_name

Description: Creates a new container without starting it.

Docker Networking

List networks:

docker network ls

Description: Lists all networks created on the Docker host.

Create a network:

docker network create my_network

Description: Creates a user-defined bridge network named 'my_network'.

Inspect a network:

docker network inspect my_network

Description: Displays detailed information about the 'my_network' network.

Remove a network:

docker network rm my_network

Description: Removes the 'my_network' network.

Connect a container to a network:

docker network connect my_network container_name

Description: Connects a container to the 'my_network' network.

Disconnect a container from a network:

docker network disconnect my_network container_name

Description: Disconnects a container from the 'my_network' network.

Attach a container to multiple networks:

docker network connect my_network_2 container_name

Description: Attaches the container to an additional network 'my_network_2'.

Create an overlay network:

docker network create --driver overlay my_overlay_network

Description: Creates a multi-host overlay network 'my_overlay_network'.

Remove all unused networks:

docker network prune

Description: Removes all networks not used by at least one container.

Set up a custom bridge network:

docker network create --driver bridge --subnet=192.168.5.0/24 --gateway=192.168.5.1 my_custom_network

Description: Creates a custom bridge network 'my_custom_network' with specified subnet and gateway.

Limit container bandwidth on a network:

docker network create --driver bridge --subnet=192.168.5.0/24 --gateway=192.168.5.1 --opt "com.docker.network.bridge.enable_icc=false" my_secure_network

Description: Creates a secure bridge network 'my_secure_network' disabling inter-container communication.

Docker Volumes

List volumes:

docker volume ls

Description: Lists all volumes on the Docker host.

Create a volume:

docker volume create my_volume

Description: Creates a named volume named 'my_volume'.

Inspect a volume:

docker volume inspect my_volume

Description: Displays detailed information about the 'my_volume' volume.

Remove a volume:

docker volume rm my_volume

Description: Removes the 'my_volume' volume.

Remove all unused volumes:

docker volume prune

Description: Removes all volumes not used by at least one container.

Mount a volume while running a container:

docker run -v my_volume:/path/in/container image_name

Description: Mounts the 'my_volume' volume to a specific path inside the container.

Mount a host directory as a volume:

docker run -v /host/path:/container/path image_name

Description: Mounts a directory from the host system into the container.

Specify volume driver:

docker volume create --driver my_driver my_volume

Description: Creates a volume using a specific volume driver 'my_driver'.

Copy files from a container volume to the local host:

docker cp container_id:/path/in/container /local/host/path

Description: Copies files from a container volume to a directory on the local host.

Mount a read-only volume:

docker run -v my_volume:/path/in/container:ro image_name

Description: Mounts the 'my_volume' volume as read-only inside the container.

Mount a named volume with specific options:

docker run -v my_volume:/path/in/container:options image_name

Description: Mounts the 'my_volume' volume with specific options (e.g., read-write permissions).

Backup a volume to a tar archive:

docker run --rm -v my_volume:/data -v /backup:/backup ubuntu tar cvf /backup/my_volume_backup.tar /data

Description: Creates a tar archive of the 'my_volume' volume in the /backup directory.

Docker Compose

Create and start containers:

docker-compose up

Description: Builds, (re)creates, starts, and attaches to containers for a service.

Stop and remove containers:

docker-compose down

Description: Stops and removes containers, networks, volumes, and images created by 'up' command.

Build services:

docker-compose build

Description: Builds or rebuilds services defined in the docker-compose.yml file.

Start services:

docker-compose start

Description: Start services defined in the docker-compose.yml file.

Stop services:

docker-compose stop

Description: Stops services defined in the docker-compose.yml file without removing containers.

Restart services:

docker-compose restart

Description: Restarts services defined in the docker-compose.yml file.

Pause services:

docker-compose pause

Description: Pauses all services in the docker-compose.yml file.

Unpause services:

docker-compose unpause

Description: Unpauses all paused services in the docker-compose.yml file.

View service logs:

docker-compose logs

Description: Displays log output from services.

Scale services:

docker-compose scale service_name=num_of_instances

Description: Scale services to a specified number of instances.