What is Docker?
A software framework for creating, executing, and managing containers on servers and in the cloud, Docker is a branch of the Moby project. Both the tools (commands and a daemon) and the Dockerfile file format can be referred to as "docker."
When you wanted to operate a web application in the past, you would purchase a server, install Linux, build up a LAMP stack, and then launch the application. In order to prevent the application from crashing due to excessive traffic, you should practice proper load balancing by putting up a second server if your app became popular.
But now that technology has advanced, the Internet is now based on clusters of redundant, interconnected servers, which is referred to as "the cloud" informally. Linux kernel namespaces and cgroups are two examples of inventions that allowed the idea of a server to be freed from the limitations of hardware and transform into, effectively, a piece of software. These software-based servers are known as containers, and they combine a hyper-localized runtime environment with the Linux OS on which they are built (the contents of the container).
For what Purpose Docker is Used:
By enabling developers to operate in standardized environments utilizing local containers that deliver your applications and services, Docker speeds the development process. Continuous Integration and Continuous Delivery (CI/CD) workflows benefit greatly from the use of containers.
Consider the following example scenario:
⦁ Using Docker containers, your engineers collaborate with their peers while writing code locally.
⦁ They run both automated and manual tests using Docker to deliver their applications into a testing environment.
⦁ Developers who discover defects can correct them in the development environment and then re-deploy them to the test environment for testing and validation.
⦁ Pushing the revised image to the production environment is all that is required after testing to provide the patch to the customer.
Docker Architecture.
Client-server architecture is used by Docker. The Docker client communicates with the Docker daemon, which manages the creation, execution, and distribution of your Docker containers. You can connect a Docker client to a distant Docker daemon or execute the Docker client and daemon on the same machine. UNIX sockets, a network interface, or a REST API are used by the Docker client and daemon for communication. Docker Compose is another Docker client that enables you to deal with programmes made up of a collection of containers.
Docker Desktop Application.
You may create and share containerized applications and microservices using Docker Desktop, an application that is simple to install on Mac, Windows, or Linux systems. Docker Desktop comes with Kubernetes, Credential Helper, Docker Compose, Docker Content Trust, Docker Daemon (dockerd), and Docker Client (docker). See Docker Desktop for more details.
Containers.
A runnable instance of an image is known as a container. Using the Docker API or CLI, you can create, start, stop, move, or destroy a container. You can attach storage to a container, connect it to one or more networks, or even construct a new image depending on the state of the existing one.
A container's isolation from other containers and its host machine is often good by default. You can manage how a container's storage, network, and other underlying subsystems are isolated from one another and from the host computer.