What are the goals and objectives of Docker in production?

Question

linux

Hello.
I am engaged in web development, both writing code and a little administration of linkus servers.
Heard and read a lot of hype around docker and vagrant.
If I have a friendship with a vagrant, for me it is a convenience for local development. I can make my own image with a provisioned file, in which I will download everything I need for my web project and use this virtual machine as a web server fully configured as I need, and also share it with my colleagues so that they don’t suffer, then with docker for me it's not so clear.
It is not clear what are the real goals and objectives of the docker in production. what is the task level?
It would be desirable to hear answers who really yuzat, responses, pluses and minuses, a range of tasks.
There was an idea that it is possible to roll software into containers on several servers (whether it be different projects or one project spaced across different servers, but there is no certainty that this is not overengineering, since in principle ansible will cope with this to some extent).
What are you doing as a docker?

Answer 1

vagrant is a ready-made virtual machine in which everything is piled up.
docker is a container of isolated applications, which allows you to quickly steer them as you like and at the same time save on resources.

Answer 2

I use docker containers as lightweight virtual machines, which are much easier to manipulate. And the toad for configs like "only nginx will work on this virtual machine, on this only php-fpm, on this only postgre, this one will fumble static files for nginx and php-fpm, this one will contain the cache, here the files uploaded by users and here is the database