Feat: multiple endpoints using a list of LitServer

[bhimrazy]

Before submitting

• Was this discussed/agreed via a Github issue? (no need for typos and docs improvements)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure to update the docs?
• Did you write any new necessary tests?

⚠️ How does this PR impact the user? ⚠️

As a user, I want to host multiple endpoints for different purposes, such as serving an embedding API, prediction API, etc., on the same server while maintaining LitServer features.

What does this PR do?

Fixes #271.

• This PR introduces a feature that allows running multiple LitServer instances in a combined form, as discussed in issue Is it possible to support multiple endpoints for one server? #271.

Usage

# server.py
from litserve.server import LitServer, run_all
from litserve.test_examples import SimpleLitAPI


class SimpleLitAPI1(SimpleLitAPI):
    def setup(self, device):
        self.model = lambda x: x**1


class SimpleLitAPI2(SimpleLitAPI):
    def setup(self, device):
        self.model = lambda x: x**2


class SimpleLitAPI3(SimpleLitAPI):
    def setup(self, device):
        self.model = lambda x: x**3


class SimpleLitAPI4(SimpleLitAPI):
    def setup(self, device):
        self.model = lambda x: x**4


if __name__ == "__main__":
    server1 = LitServer(SimpleLitAPI1(), api_path="/predict-1")
    server2 = LitServer(SimpleLitAPI2(), api_path="/predict-2")
    server3 = LitServer(SimpleLitAPI3(), api_path="/predict-3")
    server4 = LitServer(SimpleLitAPI4(), api_path="/predict-4")
    run_all([server1, server2, server3, server4], port=8000)

# client.py
import requests

for i in range(1, 5):
    resp = requests.post(f"http://127.0.0.1:8000/predict-{i}", json={"input": 4.0}, headers=None)
    assert resp.status_code == 200, f"Expected response to be 200 but got {resp.status_code}"
    assert resp.json() == {"output": 4.0**i}, f"Expected response to be {4.0**i} but got {resp.json()}"

PR review

Anyone in the community is free to review the PR once the tests have passed.
If we didn't discuss your PR in GitHub issues there's a high chance it will not be merged.

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[codecov]

Codecov Report

Attention: Patch coverage is 98.43750% with 1 line in your changes missing coverage. Please review.

Project coverage is 95%. Comparing base (f475369) to head (e5db967).

Additional details and impacted files

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##           main   #276   +/-   ##
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  Coverage    95%    95%           
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  Files        14     14           
  Lines      1082   1143   +61     
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+ Hits       1025   1085   +60     
- Misses       57     58    +1     

[aniketmaurya]

Awesome @bhimrazy!! We might have to look into mounting FastAPI app instances like here so that the endpoints are visible from all the uvicorn servers.

[williamFalcon]

ok, let's pause this for now while we validate with customers what is a real use case...
rushing into something will only complicate the codebase, without no real user proof of exactly what problems this solves for them...

this feels very "theoretical" at this stage... i want to root this with user feedback first @lantiga @aniketmaurya

[aceliuchanghong]

still can't use this function

[VikramxD]

In the meantime , this gets merged , is there any other way to run multiple endpoints in one main server ?

[williamFalcon]

this is paused and not scheduled to be merged until we have a very clear usecase.

so, the best way to unblock this is to share code of what you are trying to do and why you wouldn’t just run two separate servers on the same machine?

@VikramxD