[IMPL] - Custom backend server and improved configuration capabilities

[KronosDev-Pro]

Idea

Customize the backend server configuration as you like, and create a complete new backend server support.

can be easily split into another reflex package, for example pip install reflex[granian].

Example

We can define which BackendServer to use for development and production modes and thus customize the configuration (all parameters for each BackendServer are the actual parameters corresponding to the web server involved).

import reflex as rx
from reflex import server

config = rx.Config(
    app_name="examples",
    backend_server_dev = server.GunicornBackendServer(
        worker_class="uvicorn.workers.UvicornH11Worker",
        max_requests=100,
        max_requests_jitter=25,
        timeout=120,
        threads=1,
        workers=1,
    ),
    backend_server_prod = server.GranianBackendServer(
        threads=2,
        workers=4,
    )
)

We can also create a customized BackendServer with the CustomBackendServer class, such as GranianBackendServer

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All Submissions:

• [x] Have you followed the guidelines stated in CONTRIBUTING.md file?
• [x] Have you checked to ensure there aren't any other open Pull Requests for the desired changed?

Type of change

• [x] New feature (non-breaking change which adds functionality)
• [x] This change requires a documentation update

New Feature Submission:

• [x] Does your submission pass the tests?
• [x] Have you linted your code locally prior to submission?

Changes To Core Features:

• [x] Have you added an explanation of what your changes do and why you'd like us to include them?
• [ ] Have you written new tests for your core changes, as applicable?
• [x] Have you successfully ran tests with your changes locally?

[mmmcorpsvit]

hm... why not just use Pydantic Config package?

[KronosDev-Pro]

hm... why not just use Pydantic Config package?

Basically, dataclasses is a native package that brings simplicity, performance and more customization possibilities. What's more, for this type of configuration, it doesn't need the validation and serialization/deserialization provided by pydantic.