Docker Review

 

Today I want to explain some information from what I learned in the class and some sources outside.

What is Docker?

Docker is a package of Linux containers, providing a simple and easy to use container interface. It is by far the most popular Linux container solution. It is a kind of visual machine but it also has differences from the visual machine.

Docker packages the application and its dependencies in a single file. Running this file generates a virtual container. The program runs in this virtual container as if it were running on a real physical machine. With Docker, you don't have to worry about the environment.

Generally speaking, Docker's interface is quite simple. Users can easily create and use containers and put their own applications into the containers. Containers can also be versioned, copied, Shared, and modified just like normal code.

The main USES of Docker currently fall into three categories. First, provide a disposable environment. Examples include testing other people's software locally and providing a unit test and build an environment for continuous integration. Second, provide flexible cloud services. Because Docker containers can be opened and closed on demand, they are ideal for dynamic dilatation and shrinkage. Third, establish micro-service architecture. With multiple containers, a machine can run multiple services, so the microservice architecture can be simulated on its own.

Docker mainly contains three basic concepts, namely image, container, and warehouse. Once you understand these three concepts, you can understand the entire life cycle of Docker. The following is a brief summary of these three points that we have a short view of the class.

Docker image is a special file system that not only provides the programs, libraries, resources, configuration files required by the container runtime but also contains some configuration parameters for the runtime. 

The essence of containers is processed, but unlike processes that execute directly on the host, container processes that run in their own separate namespace containers can be. Create, start, stop, delete, pause, and so on, the relationship between an image and a container is analogous to classes and instances in object-oriented programming.

Once the image is built, it is easy to run on the current host, but if you need to use the image on other servers, you need a centralized service to store and distribute the image, and Docker Registry is one such service. A Docker Registry can contain multiple repositories; Each warehouse can contain multiple tags; Each label corresponds to an image, where the label can be understood as the version number of the image.

On the whole, Docker is a concept that is more and more interesting, which is worth our in-depth understanding. 

Sources:

https://medium.com/codingthesmartway-com-blog/docker-beginners-guide-part-1-images-containers-6f3507fffc98

https://docs.docker.com/get-started/part2/



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