Docker is a containerization platform that enables developers to package applications and their dependencies into lightweight, portable containers. These containers run consistently across different environments, from a developer's laptop to production servers.
Core Components
- Docker Engine: The runtime that enables containerization functionality.
- Docker Images: Read-only templates that contain the application code, libraries, dependencies, and system tools needed to run the application.
- Docker Containers: Runnable instances of Docker images that execute the application in an isolated environment.
- Dockerfile: A text document containing instructions for building a Docker image.
- Docker Hub: A cloud-based registry service for sharing and distributing Docker images.
Key Benefits
- Consistency: Ensures applications run the same regardless of where they're deployed.
- Isolation: Applications run in isolated environments preventing conflicts between dependencies.
- Efficiency: Containers share the host OS kernel, making them more lightweight than virtual machines.
- Portability: Applications can run on any system with Docker installed.
- Fast Deployment: Reduces the time between writing code and running it in production.
- Version Control: Docker images can be versioned and managed like code.
Common Commands
docker run: Creates and starts a new container from an imagedocker build: Builds an image from a Dockerfiledocker pull: Downloads an image from a registrydocker push: Uploads an image to a registrydocker ps: Lists running containersdocker logs: Shows output from a container
Use Cases
- Microservices architecture
- Continuous integration and deployment (CI/CD)
- Development environment standardization
- Application modernization
- Hybrid and multi-cloud deployments