Docker is a powerful platform designed to make it easier to create, deploy, and run applications by using containers. Containers allow a developer to package up an application with all of the parts it needs, such as libraries and other dependencies, and ship it all out as one package. This means that the application will run on any other machine regardless of any customized settings that machine might have that could differ from the machine used for writing and testing the code.
Here's a breakdown of the key aspects of Docker:
1. Containers
Containers are at the heart of Docker. They are lightweight, standalone, executable packages that include everything needed to run a piece of software, including the code, runtime environment, libraries, environment variables, and configuration files. Containers are isolated from each other and the host system, but they share the host OS kernel, making them more efficient and smaller in size than traditional virtual machines.
2. Images
A Docker container is built from a Docker image. These images are the building blocks of containers. An image is essentially a snapshot of a container, capturing its specific configuration. Docker images are often created by combining and modifying standard images downloaded from public repositories such as Docker Hub.
3. Docker Hub
Docker Hub is a service provided by Docker for finding and sharing container images with your team. It is a huge library of over 100,000 applications packaged in containers and ready to be used.
4. Dockerfile
A Dockerfile is a text document that contains all the commands a user could call on the command line to assemble an image. Using docker build users can create an automated build that executes several command-line instructions in succession.
5. Portability
Since Docker containers can run on any Docker host, on any platform, and in any cloud, the portability and ease of deployment are huge advantages. This makes it easy for developers to develop on their laptops and be assured that their applications will run identically in any other environment.
6. Microservices
Docker is ideal for microservices architecture. You can build each component or module of your application in a separate container. This not only keeps the development organized but also allows each service to scale independently.