What is saved in the container docker image?

Question

Docker

When we build on the basis of the image and push to register our own image, what is saved there? for example, we have a php-fpm image

1) Are the installed dependencies (composer, libraries, such as pdo, etc.) stored in the image?
2) Are the files that appeared as a result of executing commands from the dockerfile, such as composer install and so on, saved?
3) Is the code of the project itself saved inside the image? For example, I have seen projects that are installed from images from their registry, where there are no volumes to the folder with the project itself, but only to the public folder. That is, the entire code of the project is somehow sewn inside the image? How is it done and why?
4) What are their images usually used for and what scenario? The image is built, sent to the registry, and then, for example, this image is raised on a test server, or on a prod? That is, you don’t need to build a running image, it’s already ready, you just need to run it? And all the files are already sewn into it. needed for the project to work?

Answer 1

Why do you need docker for PHP? And it works so great.
Everything in the host's home directory, logs, configs will be saved. You sweat to share.

Answer 2

Better look away
https://github.com/arut/nginx-rtmp-module
is simpler and does not eat memory like wowza

Answer 3

If you are interested in Vovza, you need to be patient and study the methods of setting it up. Here, as they say, "it's better to lose a day, then fly in 5 minutes."
For your question, take a look at this article .
You can also use our control panel for Wowza .