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This article mainly introduces "what can be done with Docker". In daily operation, I believe many people have doubts about what can be done with Docker. The editor consulted all kinds of materials and sorted out simple and easy-to-use operation methods. I hope it will be helpful to answer the doubts about "what can be done with Docker"! Next, please follow the editor to study!

Brief introduction of 1.0 container

The difference between container and hypervisor virtualization:

Hypervisor virtualization virtualizes one or more independent machines on physical hardware through the middle tier

The container is the user space that runs directly on the operating system kernel. Therefore, container virtualization is also called "operating system-level virtualization".

Because the guest resides in the operating system, the container can only run the same or similar operating system as the underlying host.

Compared with traditional virtualization and paravirtualization, container operation does not need simulation layer and management layer, but uses the system call interface of the operating system, which reduces the overhead.

Of course, the container also has some limitations, such as it is considered by some people to be unsafe, its technology is complex, and it is not easy to install and automate.

1.1 introduction to Docker

Docker is an open source engine that automatically deploys developed applications to containers. Its goal is to provide a lightweight, fast environment that can run the developer's program, and deploy the program from the developer's laptop to the test environment, and then to the production environment.

Docker wants to provide the following features for program development:

Provide a simple, lightweight modeling method. You can Dockerize your program in a few minutes and use the "copy-on-write" model to make changes to the application very quickly. Creating containers to run applications is also fast, and a host can run many containers so that users can make full use of system resources.

The logical separation of responsibilities. With Docker, developers only need to relate to the applications running in the container, while operators only need to relate to how the container is managed. At the same time, strengthen the consistency between the development environment in which developers write code and the production environment in which the application is to be deployed.

A fast and efficient development life cycle. One of the purposes of Docker is to shorten the cycle of code from development, testing to deployment and running online, making applications portable, easy to build, and easy to collaborate.

Encourage the use of service-oriented architecture. Docker recommends that a single container run only one application or process so that a distributed application model can be formed. In this model, applications or services can be represented as a series of interconnected containers, making it easy to deploy applications, extend or debug applications in a distributed manner.

1.2 Docker components

Docker client and server. The Docker client only needs to make a request to the Docker server or daemon, which does all the work and returns the result. Docker provides a command line tool, docker, and a set of RESTful API. You can run daemons and clients on the same host, or you can connect from a local Docker client to a remote Docker daemon running on another host.

Docker image. Mirror image is the cornerstone of building the Docker century. Users run their own containers based on images. Mirroring is also a "build" part of the Docker lifecycle. Mirroring is a hierarchical structure based on the Union file system, which is built step by step by a series of instructions. You can also use the image as the "source code" of the container. The mirror image is small, portable and easy to share, store and update. You can use an existing image, or you can build your own.

Registry . Docker uses Registry to save user-built images. Registry is divided into public and private. The public Registry operated by Docker is called Docker Hub. Users can register an account, share and save their own images. Mirroring on Docker Hub includes mirroring of Nginx Web Server, mirroring of MySQL database, and so on. You can also assume your own private Registry.

The container. Docker can help build and deploy containers by packaging your own applications or services into the container. The container is started based on an image, and one or more processes can be run in the container. You can think of a mirror as the build or packaging phase in the Docker lifecycle, while the container enables the startup or execution phase. To sum up, the Docker container is: an image format, a series of standard operations, and an execution environment.

1.3 what can we do with Docker

Accelerate the local development and build process to make it more efficient and lightweight. Local developers can build, run, and share Docker containers. Containers can be built in the development environment, then easily submitted to the test environment, and eventually into the production environment

Allows stand-alone services or applications to get the same results in different environments. This is especially useful in service-oriented architectures and deployments that rely heavily on micro-services

Use Docker to create an isolated environment for testing. For example, start a container for testing with a continuous integration tool like Jenkins CI

Docker allows developers to build a complex program or architecture on the machine for testing instead of deploying and testing in a production environment at the beginning.

Build a multi-user platform-as-a-service infrastructure

Provide a lightweight independent sandboxie environment for development and testing, or use the independent sandboxie environment for technical teaching.

Provide software-as-a-service applications such as Memcached as a service

High-performance, very large-scale host deployment.

At this point, the study of "what can be done with Docker" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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