What is Docker used for?
With Docker technology, you can treat containers as very lightweight, modular virtual machines. In addition, these containers offer you great flexibility: you can create, deploy, copy and move them from one environment to another, allowing you to optimise your applications for the cloud.
Images Docker, conteneurs, Dockerfile
Image Docker
The Docker image is a template required to run an application. It consists of application code, libraries, tools, dependencies, etc.
Docker images are read-only immutable files, sometimes also called snapshots. You do not start or run a Docker image; you build a container through it. When a container is created from a Docker image, it creates a layer of containers on top of the image layer.
There must be a base docker image that is used to create several other docker images with some modifications to the base image.
Docker Hub is a repository of Docker images for almost every technology stack. You can pull a Docker image from DockerHub and start creating containers.
Docker Containers
Docker containers are executable software packages that include all the dependencies required to run an application. With Docker containers, applications can run efficiently in different computing environments.
Here are the features of Docker containers:
- Lightweight
- Minimal overhead (CPU / E / S / network)
- Faster deployments
- Easily scalable
- Decrease storage consumption
- Portable, run it anywhere.
- Minimal base operating system
- Application isolation
Dockerfile
Dockerfile is a shell script that defines all the tasks to be performed. From a docker file, you create a docker image; from the docker image, you create a docker container.
Installing Docker
Docker can be easily installed on various Linux, Windows or macOS platforms. See this post on How to install Docker on Ubuntu, CentOS, Debian and Windows.
Also, Docker Desktop is available for Windows and Mac machines. It is a very easy to install executable application that allows you to create and containerise applications on Windows and Mac environments.
Docker editions and prices
There are two editions of Docker:
- Community Edition (CE)
- Enterprise Edition (EE)
The Docker Community Edition is open source and free. Docker CE aims at a “do it yourself” approach where DevOps engineers can containerise their application by themselves.
The Docker Enterprise Edition comes with three versions – Essential, Standard, and Advanced. The Basic Edition comes with Docker platform, support and certification, while the Standard and Advanced Editions come with Docker container management and security analysis features added to the Basic Edition features.
Most techies use Docker for free. But if you need advanced features, you can use the paid version of Docker. The price depends on features such as repository management, CI/CD features, user management, development tools and support options.
Here are the details of the Docker plan:
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