Docker Basics

source: cto.ai

Docker is a platform for developers and sysadmins to develop, deploy, and run applications with containers.

• Container: A container is a standard unit of software that packages up code and all its dependencies so the application runs quickly and reliably from one computing environment to another.
• Image: An image is a read-only template with instructions for creating a Docker container.
• Dockerfile: A Dockerfile is a text document that contains all the commands a user could call on the command line to assemble an image.

General Commands

• docker --version - Show the Docker version information
• docker info - Display system-wide information
• docker --help - Show help
• docker system df - Show Docker disk usage

Images

Build

• docker build -t <image_name> . - Build an image from a Dockerfile
  • -t flag is used to tag the image with a name
  • . is the path to the Dockerfile
• docker build -t <image_name> -f <Dockerfile_name> . - Build an image from a specific Dockerfile
• docker build -t <image_name> --no-cache .
  • --no-cache flag can be used to build the image without cache, for more info check FreeCodeCamp's tutorial here.
• docker buildx prune - Remove build cache

Manage

• docker images - List all images
• docker image rm <image_id> - Remove an image
  • Alias: docker rmi <image_id>
• docker image prune - Remove all dangling images
  • Dangling images are images that have no tag and are not used by any container
• docker image prune -a - Remove all images that are not used by any container
• docker pull <image_name> - Pull an image from the registry
  • e.g.: Getting IoTDB official image docker pull apache/iotdb:1.0.1-standalone

Containers

Create and Run

• docker run --name <container_name> <image_name> - Create and run a container
• docker run -p <host_port>:<container_port> <image_name> - Map a host port to a container port
• docker run -d <image_name> - Run a container in detached mode (background)

<image_name> should always be the last argument in the command.

Start and Stop

• docker start <container_id> - Start a container
• docker stop <container_id> - Stop a container

Manage

• docker ps - List all running containers
• docker ps -a - List all containers (running and stopped)
• docker rm <container_id> - Remove a container
• docker container prune - Remove all stopped containers
• docker container stats - Display a live stream of container(s) resource usage statistics
• docker logs <container_id> - Fetch the logs of a container
• docker exec -it <container_id> CONTAINER COMMANDS - Execute a command in a running container
  • -it flags are used to open an interactive terminal
  • bash is the command to execute
  • e.g.: docker exec -it <container_id> bash