Why do I need docker, vagrant if there is openserver, denwer?

Question

Denver

Apologies in advance if this is a stupid question. Just explain to a newbie. Why are they if there are those two.
As I understand now: docker, vagrant are used when we want to upload a project to a dedicated server. And when we want to upload openserver to virtual hosting where, say, apache, php, etc. are already installed

Answer 1

As I understand now: docker, vagrant are used when we want to upload a project to a dedicated server. And when we want to upload openserver to virtual hosting where, say, apache, php, etc. are already installed

No.
Vagrant is just a convenient way to configure and run software in an isolated environment.
Development oriented.
Docker is a way to isolate development, deployment, and operations, again with its own convenience.
The key word is isolation.
It is really impossible to use Docker on classic shared hosting. On VDS/VPS - maybe you're right.
About the problem of isolation:
Any software needs a certain environment. Libraries, other services (for example, a DBMS), configuring in a certain way, file location, etc.
There are situations when, being debugged on one computer, the software, when transferred to another, categorically refuses to work.
The simplest situation is due to a lack of modules/libraries/services. If so, they can simply be delivered (although this is also time for disassembly).
A more complicated situation is when more than one key software is required on the computer. And the modules/libraries of these different programs come into conflict (different versions are required).
That's not to deal with all this - and Docker was invented.
You debug in a well-defined environment and with well-defined settings - and transfer it to the production system in exactly the same form.
Vagrant is just a developer convenience.
To quickly recreate certain settings.

Answer 2

If you want to catch errors twice, first on Windows, and then on production, then you don’t need either vagrant or virtual machines

Answer 3

1. I recommend not to use denwer
2. If you don't need docker, don't use it.
3. I think that this question would not arise if you read "What is docker?". Fortunately, there are enough materials on this topic (videos, articles and books)
4. After you understand the general concepts of docker and what it is used for. Check out this very interesting article https://habr.com/company/flant/blog/334470/

Answer 4

1. Identity of the environment during development and production
2. denwer is already obsolete, and on openserver it will be more difficult to set up a non-traditional environment
+ eth

Answer 5

If a person did not bother to read the description of the products, is it worth spending your time explaining the difference between warm and soft?

Answer 6

Denver, openserver are excellent products for developing websites, it is possible to host a simple website at home on a home PC. It's like a swiss knife built from apache, nginx, php. But if you have a large resource, loaded and should work in any conditions 24/7, you start setting up each component, develop some settings, test others, and work on the third. Previously, for this, they usually put the entire economy into virtual machines. Big and powerful. Vagrant helps by automating the management of this. And now it has its own set like Denver comes in a container, each version has its own. You write once, you test it, it, to the byte is the same, works in battle.