Docker
Docker
Docker is a containerization platform that enables the development, deployment, and scaling of applications in isolated, lightweight containers. The key components of Docker include:
Docker Engine
The core of Docker that runs and manages containers. This Consists of a daemon process (dockerd) and a command-line interface (CLI) tool (docker).
docker --version: Display Docker version.docker info: Display system-wide information.docker help: Display help information.
Images
A lightweight, standalone, and executable package that includes everything needed to run a piece of software, such as the code, runtime, libraries, and system tools. Images are built from a Dockerfile and can be shared and versioned through Docker registries.
docker images: List all images.docker pull <image>: Download an image from a repository.docker build -t <tag> .: Build an image from the current directory's Dockerfile.
Containers
An instance of a Docker image that runs as a process on the host machine. Containers are isolated from each other and the host system, providing consistency across different environments.
docker ps: List running containers.docker ps -a: List all containers (running and stopped).docker run <image>: Create and start a container from an image.docker exec -it <container> <command>: Execute a command in a running container.
Networking
Enables communication between Docker containers and between containers and the host system. Docker provides various network drivers, and users can create custom networks to isolate and control traffic.
docker network ls: List all networks.docker network create <name>: Create a network.docker run --network=<network> <image>: Run a container in a specific network.
Volumes
A persistent data storage mechanism in Docker. Volumes can be used to share data between containers, persist data beyond the lifecycle of a container, and facilitate easy data backup and restore.
docker volume ls: List all volumes.docker volume create <name>: Create a volume.docker run -v <volume>:<container_path> <image>: Mount a volume to a container.
Compose
A tool for defining and managing multi-container Docker applications using a YAML file (docker-compose.yml). Allows you to define the services, networks, and volumes required for an application, making it easier to manage complex deployments.
docker-compose up: Start services defined indocker-compose.yml.docker-compose down: Stop and remove containers defined indocker-compose.yml.
Dockerfile Directives
A text file containing instructions for building a Docker image. Defines the base image, adds application code, specifies dependencies, and configures runtime settings.
- FROM: Base image for building.
- COPY: Copy files or directories into the image.
- RUN: Execute commands in the image.
- EXPOSE: Specify ports to expose.
- CMD: Default command to run when the container starts.
Docker Registry
A centralized repository for storing and sharing Docker images. Examples include Docker Hub, a public registry, and private registries that organizations set up for their specific needs.
docker login: Log in to a Docker registry.docker push <image>: Push an image to a registry.docker pull <registry>/<image>: Pull an image from a registry.
Cleanup
docker system prune: Remove all stopped containers, unused networks, and dangling images.docker volume prune: Remove all unused volumes.
Docker Hub
A cloud-based registry service provided by Docker for sharing and managing Docker images. Developers can push and pull images to and from Docker Hub, making it a central hub for the Docker community.