azure-functions-openapi 0.4.0

OpenAPI (Swagger) integration for Python-based Azure Functions

azure-functions-openapi

Effortless OpenAPI (Swagger) documentation & Swagger‑UI for Python Azure Functions.

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Features

• @openapi decorator — annotate once, generate full spec
• Serves /openapi.json, /openapi.yaml, and /docs (Swagger UI)
• Supports query/path/header parameters, requestBody, responses, tags
• Optional Pydantic integration (supports both v1 and v2)
• Zero hard dependency on Pydantic

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Installation

pip install azure-functions-openapi

For local development:

git clone https://github.com/yeongseon/azure-functions-openapi.git
cd azure-functions-openapi
pip install -e .[dev]

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Quick Start

Create a minimal HTTP-triggered Azure Function with auto Swagger documentation.

1. Set up environment

python -m venv .venv
source .venv/bin/activate
pip install azure-functions azure-functions-worker azure-functions-openapi

2. Initialize Azure Functions project

func init hello_openapi --python
cd hello_openapi

3. Add function_app.py with OpenAPI-decorated function and endpoints:

# hello_openapi/function_app.py

import json
import azure.functions as func
from azure_functions_openapi.decorator import openapi
from azure_functions_openapi.openapi import get_openapi_json, get_openapi_yaml
from azure_functions_openapi.swagger_ui import render_swagger_ui

app = func.FunctionApp()

@openapi(
    summary="Greet user",
    route="/api/http_trigger",
    request_model={"name": "string"},
    response_model={"message": "string"},
    tags=["Example"]
)
@app.function_name(name="http_trigger")
@app.route(route="/api/http_trigger", auth_level=func.AuthLevel.ANONYMOUS, methods=["POST"])
def main(req: func.HttpRequest) -> func.HttpResponse:
    try:
        data = req.get_json()
        name = data.get("name", "world")
        return func.HttpResponse(
            json.dumps({"message": f"Hello, {name}!"}),
            mimetype="application/json"
        )
    except Exception as e:
        return func.HttpResponse(f"Error: {str(e)}", status_code=400)

@app.function_name(name="openapi_json")
@app.route(route="/api/openapi.json", auth_level=func.AuthLevel.ANONYMOUS, methods=["GET"])
def openapi_json(req: func.HttpRequest) -> func.HttpResponse:
    return get_openapi_json()

@app.function_name(name="openapi_yaml")
@app.route(route="/api/openapi.yaml", auth_level=func.AuthLevel.ANONYMOUS, methods=["GET"])
def openapi_yaml(req: func.HttpRequest) -> func.HttpResponse:
    return get_openapi_yaml()

@app.function_name(name="swagger_ui")
@app.route(route="/api/docs", auth_level=func.AuthLevel.ANONYMOUS, methods=["GET"])
def swagger_ui(req: func.HttpRequest) -> func.HttpResponse:
    return render_swagger_ui()

Swagger UI (/docs) is now supported via render_swagger_ui() helper.

4. Run locally:

func start

• OpenAPI JSON: http://localhost:7071/api/openapi.json
• Swagger UI: http://localhost:7071/api/docs

5. Deploy:

func azure functionapp publish <FUNCTION-APP-NAME> --python

• OpenAPI JSON: https://.azurewebsites.net/api/openapi.json

A partial example of the generated /api/openapi.json:

{
  "openapi": "3.0.0",
  "info": {
    "title": "API",
    "version": "1.0.0",
    "description": "Auto-generated OpenAPI documentation. Markdown supported in descriptions (CommonMark)."
  },
  "paths": {
    "/api/http_trigger": {
      "get": {
        "summary": "HTTP Trigger with name parameter",
        "description": "Returns a greeting using the **name** from query or body.",
        "parameters": [
          {
            "name": "name",
            "in": "query",
            "required": true,
            "schema": { "type": "string" },
            "description": "Name to greet"
          }
        ],
        "responses": {
          "200": {
            "description": "Successful response with greeting",
            "content": {
              "application/json": {
                "examples": {
                  "sample": {
                    "summary": "Example greeting",
                    "value": {
                      "message": "Hello, Azure!"
                    }
                  }
                }
              }
            }
          },
          "400": { "description": "Invalid request" }
        }
      }
    }
  }
}

• Swagger UI: https://.azurewebsites.net/api/docs

Swagger UI will look once you set up the routes:

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Example with Pydantic

from pydantic import BaseModel
from azure_functions_openapi.decorator import openapi

class RequestModel(BaseModel):
    name: str

class ResponseModel(BaseModel):
    message: str

@openapi(
    summary="Greet user (Pydantic)",
    route="/api/http_trigger",
    request_model=RequestModel,
    response_model=ResponseModel,
    tags=["Example"]
)
def http_trigger(req: func.HttpRequest) -> func.HttpResponse:
    ...

Supports both Pydantic v1 and v2. Schema inference will work automatically with either version.

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Documentation

• Full docs: yeongseon.github.io/azure-functions-openapi
• Quickstart
• Development Guide
• Contribution Guide

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License

MIT © 2025 Yeongseon Choe