This is a solution for building versioned APIs automatically using FastAPI. It enables automatic inheritance of endpoints from previous FastAPI sub-applications into newer versions based on configuration, and correctly reflects them in the OpenAPI schema.

Documentation

pip install fastapi-easy-versioning

PyPI

To implement versioning, use the VersioningMiddleware and the dependency factory versioning.

Example:

from fastapi import FastAPI, Depends
from fastapi_easy_versioning import VersioningMiddleware, versioning

app = FastAPI()
app_v1 = FastAPI(api_version=1)
app_v2 = FastAPI(api_version=2)

app.mount("/v1", app_v1)
app.mount("/v2", app_v2)
app.add_middleware(VersioningMiddleware)

@app_v1.get('/only-v1', dependencies=[Depends(versioning(until=1))])
def only_v1() -> str:
    return "Available only in version v1"

@app_v1.get('/all-versions', dependencies=[Depends(versioning())])
def all_versions() -> str:
    return "Available in all versions starting from v1"

@app_v2.get('/from-v2', dependencies=[Depends(versioning())])
def from_v2() -> str:
    return "Available starting from v2 and in all future versions"

The endpoint /only-v1 is available only in version v1 at /v1/only-v1. The endpoint /from-v2 becomes available starting from version v2 at /v2/from-v2 and is automatically inherited in all subsequent versions. The endpoint /all-versions, defined in v1, is accessible at both /v1/all-versions and /v2/all-versions due to the inheritance mechanism.

Using the versioning dependency factory, you can specify the last version in which an endpoint remains available by setting the until parameter to a version number. If until is set to None or omitted, the endpoint will be available in the version it was declared and in all later versions.

To associate a sub-application with a specific version, use the api_version parameter when creating the FastAPI instance. It must be an integer. Sub-applications without the api_version parameter will be ignored during versioning processing.