Excursus in Russian: the essence, configuration, and use of Docker?

Question

Web development

Who has a vidos, or a manual worthy of attention, on Docker. Why is it needed, configuration, application in practice.

Answer 1

Docker - application virtualization. I'll give you an example.
You are developing a web application in java, and you need to test it under java7, java8 and under tomcat 7, tomcat 8.
You can buy 4 computers, install 4 options on them, and test. Then put everything back for the next test. Inconvenient, long, expensive.
A virtual machine comes to the rescue - you can buy 1 computer, start 4 virtual machines on it, configure each of them, save images. After testing, simply restore the original state from the images.
Much cheaper than before. But each virtual machine requires processors, memory, a lot of disk space for the operating system. But in fact, only 2 components differ.
Docker comes to the rescue. One computer, one operating system. 4 docker containers with the required version of java and tomcat. After testing, the container can be removed and deployed in advance.
Cheaper and faster than all of the above. Because there is only one operating system, there are no extra costs for CPU and memory. There is practically nowhere to squeeze further.
Of course, docker has its own limitations on its use, but roughly speaking, within one operating system, several applications can work independently, which, during a standard installation, are deployed in such a way that they could not work simultaneously. And here are two docker containers, inside which these two versions of the application are isolated and do not interfere with each other with minor exceptions (for example, a tcp port).
Application virtualization through docker avoids dll-hell, disk system and environment isolation.
PS The example is very simple and contrived, since specifically java and tomcat you can simply run several different versions on different ports without a docker, but you should get the gist. Docker - virtualization at the file system level, the cheapest virtualization.

Answer 2

There is such a site:
docker.crank.ru