Docker is a popular platform used to develop, ship, and run applications within containers. Here are some basic concepts to understand about Docker:
▣ Containerization: Docker uses containerization technology to encapsulate applications and their dependencies into lightweight, portable containers. Containers are isolated environments that package everything needed to run an application, including the code, runtime, system tools, libraries, and settings.
▣ Docker Engine: Docker Engine is the core component of Docker. It is a client-server application with the following major components:
▣ Docker Daemon: A background process running on the host system responsible for managing Docker objects such as images, containers, volumes, and networks.
▣ Docker Client: A command-line interface (CLI) tool used to interact with the Docker Daemon via the Docker API.
▣ Images: An image is a read-only template used to create Docker containers. It contains the application code, runtime, libraries, and dependencies needed to run the application. Images are built using a Dockerfile, which specifies the instructions for creating the image layer by layer.
▣ Containers: A container is a runnable instance of an image. It encapsulates the application and its dependencies, providing an isolated environment for running the application. Containers can be started, stopped, paused, and deleted using Docker commands.
▣ Dockerfile: A Dockerfile is a text file that contains instructions for building a Docker image. It specifies the base image, environment variables, commands to run during the build process, and other configuration settings. Dockerfiles are used to automate the image creation process and ensure consistency across different environments.
▣ Docker Registry: Docker Registry is a repository for storing and distributing Docker images. The Docker Hub is the official public registry provided by Docker, where users can find and share Docker images. Organizations can also set up private registries to store their proprietary Docker images securely.
▣ Docker Compose: Docker Compose is a tool used to define and run multi-container Docker applications. It uses a YAML file (docker-compose.yml) to define the services, networks, and volumes required for the application. Docker Compose simplifies the management of complex applications with multiple interconnected containers.
▣ Volumes: Volumes are used to persist data generated by Docker containers. They provide a way to store and share data between containers and the host system. Docker volumes can be managed using Docker commands or defined in Docker Compose files.
▣ Networking: Docker provides networking capabilities to connect containers running on the same host or across multiple hosts. Each container can be assigned a unique IP address and connected to one or more networks. Docker also supports network drivers to enable advanced networking features such as overlay networks and network plugins.
These are some of the fundamental concepts of Docker that developers need to understand to effectively use Docker for containerization and application deployment.
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