docker+docker-compose

Docker + Docker Compose

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Commands

Docker

• docker pull <image>: Pull Image from Docker Hub
• docker create <image>: Create a container from an Image
• docker start <container_name/container_id>: Start a container
• docker stop <container_name/container_id>: Stop a container
• docker kill <container_name/container_id>: Kill the entrypoint process of the container
• docker rm <container_name/container_id>: Remove a container
• docker ps: Get all running containers
• docker ps -a: Get all containers
• docker stop $(docker ps -a -q): Stop all containers
• docker rm $(docker ps -a -q): Remove all containers
• docker image rm $(docker image ls -q): Remove all images
• docker run --name <container_name> -p <host_port>:<container_port> <image>: Pull, create, start and run a container
• docker run -d <image>: Run in detached mode
• docker run -e <key>=<value> <image>: Run with environment variable
• docker run -it <image> <command>: Run a container and overwrite the default command
• docker run -it --entrypoint <entrypoint_command> <image>: Run a container and overwrite the default entrypoint
• docker inspect <container_name>: Get details about the container
• docker exec -it <image_name> <command>: Execute a command in a running container with interactive mode
• docker -v <volume_name>:<path_in_container> <image>: Bind path in the container to a Docker volume
• docker -v <path_in_host>:<path_in_container> <image>: Bind path in the container to another path in the host
• docker volume ls: List all volumes
• docker volume create <volume_name>: Create a Docker volume
• docker network create <network_name>: Create a user-defined network
• docker run --network=<network_name> <image>: Run a docker container in a certain network
• docker run --link=<container> <image>: Run a docker container and link network it with another container (legacy)
• docker build <path>: Build docker image
• docker build --tag <image_name> <path>: Build docker image with a tag
• docker build --platform linux/amd64 <path>: Build for a specific target platform. This is used when building on M1 Macbook but target is linux.
• docker build - < <custom_path>: Build docker image when the name is not Dockerfile
• docker tag <image_name> <company>/<new_image_name>:<version>: Add a Docker Repository tag to an image. It can be also used for adding more tags
• docker login: Log into a Docker Repository
• docker push <company>/<new_image_name>:<version>: Push to a Docker repository, ex: DockerHub
• docker commit <container_name/container_id> <image>: Create an image from a running container
• docker logs -f --tail <lines_count> <container_name>: Print number of lines of the container logs and keep streaming

Docker Compose

• docker compose build: Build services of the docker compose
• docker compose build <service>: Build a service of the docker compose
• docker compose create: create services
• docker compose start: start services
• docker compose run: Run a command in a services
• docker compose restart: Restart services
• docker compose restart <service>: Restart a service
• docker compose pause: Pause services
• docker compose unpause: Unpause services
• docker compose stop: Stop services
• docker compose rm: Remove stopped containers
• docker compose up: Create and start containers
• docker compose pull: Pull all services' images. It's good when updating services images
• docker compose up -d: Create and start containers in detached mode
• docker compose up -d <service>: Create and start containers in detached mode for a certain service
• docker compose up --scale <service>=<count>: Create and start containers and scale the number of a service
• docker compose down: Stop and remove containers
• docker compose logs -f --tail <lines_count>: Print the logs for all services
• docker compose logs -f --tail <lines_count> <service>: Print the logs for a certain services

DockerFile

• FROM <image>: Based image
• FROM <image> as <stage>: Based image, also assign name to be used for multi-stage image building
• RUN <command>: Runs a certain command inside the image
• Expose <port>/<protocol>: Used for documentation purposes to available ports
• COPY <source> <destination>: Copys file from host to image
• COPY --from=<stage> <source> <destination>: Copys file from host to image. Cross stage copy.
• ADD <source> <destination>: Similar to COPY but can also download and extract tar files
• ENV <key>=<value>: Define an environment variables
• USER <user>:<group>: Used to define a user to run the commands
• WORKDIR <destination>: Set working directory to avoid many cd
• CMD <command> <param1> ... or CMD ["<command>", "<param1>"]: The default command to run for the container
• ENTRYPOINT <command> <param1> ... or ENTRYPOINT ["<command>", "<param1>"]: The required command to run for the container.

Docker Compose File

• services: Array of services to start
  • image: Docker image name
  • build: Path to a Dockerfile
  • port: Array of exposed ports
  • environment: Array of environment variables
  • volumes: mapping of volumes
  • networks: Define used network
  • restart: Restart policy for the container. no, on-failure, always, unless-stopped
• networks: Defines available networks

Questions?

• ADD vs COPY?

  They both have similar functionality but ADD can also extract tar file and also download from the network

• CMD vs ENTRYPOINT?

  They both execute commands. Use CMD when you want the user of your image to have the flexibility to run whichever executable they choose when starting the container. Use ENTRYPOINT when you want the container to behave exclusively as if it were the executable it's wrapping.

We can combine both of them and use ENTRYPOINT when we need a command to always run when the container starts and CMD to pass the parameters. We can then allow our users to overwrite the paramters when using docker run.

Diagrams

Source: Docker Docs

Source: Docker Internals

Extra links

• Docker API Reference
• How Docker internally works
• Containers From Scratch by Liz Rice
• Valuable Docker Articles