How do I output the version of my FastAPI app?

Question

I have an application in FastAPI.

app = FastAPI( version="v0.1.0.0" )

I want to output the version of my application in a separate endpoint so another application knows what version this application is.

I want to build something like this:

@app.get("/v0/version"):
async def api_version():
     return {"version": app_version}

where the above would return {"version": 0.1.0.0"}.

However, I am not sure what to specify in the app_version field.

Answer 1

You were nearly there...

It's an attribute on the FastAPI object: https://github.com/tiangolo/fastapi/blob/master/fastapi/applications.py#L102

So you can:

from fastapi import FastAPI

app = FastAPI(version="v0.1.0.0")

@app.get("/v0/version"):
async def version():
    return {"version": app.version}

To add this to all your APIs...

Based on this answer (https://stackoverflow.com/a/70563827/202168) and this answer (https://stackoverflow.com/a/66596529/202168) I think we can make a custom router class like this:

from fastapi import FastAPI, APIRouter, Request


async def _version(request: Request):
    return {"version": request.app.version}


class VersionedAPIRouter(APIRouter):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, *kwargs)
        self.add_api_route(
            "/version",
            _version,
            methods=["GET"],
        )


v0_router = VersionedAPIRouter(
    prefix="/v0",
)

app = FastAPI(version="v0.1.0.0")
app.include_router(v0_router)