Why do you need Docker in simple words?

Question

Docker

In fact, I don’t catch up with why Docker is needed in principle, not in the sense that they say: “There are others”, but in the sense that I don’t understand the essence of the purpose of this software at all. Tell me in simple words and examples please.

Answer 1

To make it easier to install applications on different versions of Linux and not worry about the distribution, dependencies, the wrong version of the lib.
To run many instances of what, according to the developers, can only be run in one instance.
To easily and quickly deploy services.
To cram a lot of things into one server and it did not conflict with each other.
And in general, fashionably youthful, devopsics approve.

Answer 2

Docker allows you to build a distributive image of an application and run it easily. imagine you have a large cluster of machines running your applications, let's say a website with a microservices backend. When one of the machines breaks down or is taken down for maintenance, your applications can be easily transferred from it and run on another machine.
Docker provides a certain amount of isolation for your application's runtime environment, allowing you to abstract away where exactly your application is running.
This increases the availability of your application.
Ultimately, with containerization support, you can simply upload your application somewhere to the cloud and not worry at all about whether it has crashed, what the OS distribution is and whether all the necessary libraries are installed.

Answer 3

well, look. Here I am at work, I need to quickly make some kind of application for my colleagues. and it comes in different versions.
If everything is done honestly, then you need to
Raise the virtual machine, install and configure the database, upload the database dump to it, deploy the application of the required version, configure the connection to the database in the application. It all takes up to half an hour, even with Ansible.
Now we take the docker.
With one command, I roll out the application and the database of the required versions in a couple of minutes. And if necessary, next to the second instance and the third and fourth.
Only one problem is to make a container with the right version of the application, but this is a fully automated procedure that I do not waste time on.

Answer 4

Briefly: when you are tired of reinstalling php versions and so on. And when I got tired of setting it all up. And when, after another project, you want to erase everything that was from him and live in peace