Docker Basics

• Docker is a software that helps make the software development cycle more efficient by solving practical challenges.
• A lot of different objects work together to run an application inside Docker.
• An application requires objects such as Docker Images for the application code, Docker Containers to run the application, and Docker Registries to save and download Docker Images.
• Docker container is the place where the docker runs an image. You can think of it in this way as well for simplicity: Images become containers when they run on Docker Engine.
• A Docker image is a lightweight, executable package that consists of everything needed to run an application: code, libraries, third-party dependencies, environment variables, and configurations.
• A Dockerfile is a document that consists of all the commands a user wants to call on the command line to build an image.
• To be able to run the Docker Engine, you’ll need to have a supported version of CentOS. The latest version is recommended.
• In order to install the engine, we’ll first set up the docker repository and then use the repository to install the docker engine.
• The engine has been installed, but it hasn’t been started yet. Let’s start it.
• Let’s verify if the engine is able to pull an image by running the below command.
• Let’s verify if the engine is able to run a container by running the below command.

Test your understanding of Docker basics, including Docker Images, Docker Containers, Docker Registries, and Docker Engine installation and usage.