In this blog, you will learn all about
- docker engine,
- docker-compose and
- docker swarm.
What is Docker?
Docker is an open platform for system admins and developers for developing, shipping, and running applications with containers. By taking advantage of Docker’s methodologies for shipping, testing, and deploying code quickly, you can significantly reduce the delay between writing code and running it in production. The process of usage of containers to deploy applications is known as containerization.
Containers are not new but it has a worldwide use for easy deployment of the applications. But why the containers are so popular? There is not just one reason for it but many.
Containerization is popularly increasing because of these reasons:
4. Loosely coupled
Docker has the ability to run and package an application in loosely isolated environment called the container. The reason why container is lightweight, because they don’t need an extra load of hypervisor and run directly within the host machine’s kernel.
You can check these images and compare how does a container and virtual machine works. In containers, there is no extra load of the hypervisor and it runs directly into the host machine’s kernel.
To manage the lifecycle of your containers Docker provides tooling and a platform:
- Using containers develop your application and its supporting components.
- The container becomes the unit for distributing and testing your application.
- Deploy your application into your production environment, as a container or an orchestrated service when you’re ready. This works the same whether your production environment is a local data center, a cloud provider, or a hybrid of the two.
What is Docker Engine?
Docker Engine is a client-server application with some of these major components:
- Server: It is a type of a long-running program known as the daemon process(dockerd command).
- REST API: It specifies the interfaces whose programs can be used to talk to the daemon and instruct it what to do.
- Command-line interface (CLI) client (docker command)
What is Docker Compose?
Docker compose is a tool for running and defining the multi-container docker applications. With docker compose, you can use the yaml(or yml) file to configure or define multiple application services to create and run them all together with just a single command.
Basically Docker compose is a three step process:
- Your app’s environment is defined with Dockerfile so it can be reproduced anywhere.
- Define all the services that can make your app in docker-compose.yml, so that they can run together in an isolated environment.
- With the command docker-compose up , docker compose starts and run your entire services.
What is Docker Swarm?
A docker swarm consists of multiple docker hosts that runs in swarm mode and act as a workers and managers. With docker swarm, developers and IT administrations can establish and manage the cluster of docker nodes as a single virtual system.