What is Docker?
Docker is an open-source platform used for packaging and distributing software applications into lightweight, portable, and scalable containers. Docker containers provide an isolated environment that includes both the application and all its dependencies, allowing the application to run seamlessly in different environments.
Key features of Docker include:
- Containerization: Docker packages applications into containers, which are lightweight and portable units. Each container provides an isolated environment containing the application and its dependencies.
- Portability: Docker containers enable applications to run smoothly in various environments, including local machines, the cloud, and private servers. This facilitates easy deployment of applications across different platforms.
- Fast Startup and Performance: Containers start faster and use fewer system resources compared to virtual machines. This enables rapid scaling and deployment of applications.
- Independence and Isolation: Each Docker container encapsulates its own file system, network, and processes, ensuring isolation from other containers and the host system.
- Docker Hub: Docker Hub serves as a central repository for sharing and using pre-built container images. This allows users to find ready-to-launch images for their applications.
Docker accelerates and standardizes software development and deployment processes, providing significant advantages to developers and system administrators.
Installing Docker on Linux:
To install Docker, you can follow the steps below. These steps are typically performed on a Linux-based operating system. If you are using a different operating system, you can find specific instructions for your OS on the official Docker website.
- Download Docker:
- Download Docker from the official website. The following commands download Docker on Debian-based systems:
sudo apt update sudo apt install docker.io
- Download Docker from the official website. The following commands download Docker on Debian-based systems:
- Start the Docker Service:
- Use the following command to start the Docker service:
sudo systemctl start docker
- Use the following command to start the Docker service:
- Automatically Start Docker at System Boot (Optional):
- To have Docker start automatically at system boot, use the following command:
sudo systemctl enable docker
- To have Docker start automatically at system boot, use the following command:
- Check if Docker is Running Correctly:
- The following command checks if Docker is installed and running correctly:
docker --version
- The following command checks if Docker is installed and running correctly:
- Allow Docker Commands without Root (Optional):
- To run Docker commands without using sudo, add the user to the “docker” group:
sudo usermod -aG docker $USERThen, either log out and log back in or run the following command:
newgrp docker
- To run Docker commands without using sudo, add the user to the “docker” group:
Docker is now successfully installed and ready to use. To run your first Docker container, you can use official images from Docker Hub or create your own images.
Docker Commands
Here are some commonly used basic Docker commands when working with Docker:
- List Docker Images:
docker images - List Docker Containers (Running and Stopped):
docker ps -a - List Running Docker Containers:
docker ps - Pull Docker Image:
docker pull <image-name> - Create and Run Docker Container:
docker run <image-name> - Run Docker Container Detached (in the Background):
docker run -d <image-name> - Run Docker Container Detached with Port Forwarding:
docker run -d -p <local-port>:<container-port> <image-name> - Stop Running Docker Container:
docker stop <container-id or container-name> - Remove Stopped Docker Container:
docker rm <container-id or container-name> - Remove Docker Image:
docker rmi <image-name> - Enter Docker Container (Exec):
docker exec -it <container-id or container-name> /bin/bash - View Docker Container Logs:
docker logs <container-id or container-name> - Build Docker Image:
docker build -t <image-name> <dockerfile-directory> - Export/Import Docker Container:
docker export <container-id or container-name> > file.tar docker import file.tar <image-name>
These commands are commonly used for basic Docker operations. Docker provides a more extensive range of specific commands, so using the docker --help command or referring to the Official Docker Documentation can provide more detailed information.