add aiohttp reverse proxy example

examples/openapi3/reverseproxy_aiohttp/README.rst

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+=====================
+Reverse Proxy Example
+=====================
+
+This example demonstrates how to run a connexion application behind a path-altering reverse proxy.
+
+You can either set the path in your app, or set the ``X-Forwarded-Path`` header.
+
+Running:
+
+.. code-block:: bash
+
+    $ sudo pip3 install --upgrade connexion[swagger-ui]  # install Connexion from PyPI
+    $ ./app.py
+
+Now open your browser and go to http://localhost:8080/reverse_proxied/ui/ to see the Swagger UI.
+
+
+You can also use the ``X-Forwarded-Path`` header to modify the reverse proxy path.
+For example:
+
+.. code-block:: bash
+
+    curl -H "X-Forwarded-Path: /banana/" http://localhost:8080/openapi.json
+
+    {
+       "servers" : [
+          {
+             "url" : "banana"
+          }
+       ],
+       "paths" : {
+          "/hello" : {
+             "get" : {
+                "responses" : {
+                   "200" : {
+                      "description" : "hello",
+                      "content" : {
+                         "text/plain" : {
+                            "schema" : {
+                               "type" : "string"
+                            }
+                         }
+                      }
+                   }
+                },
+                "operationId" : "app.hello",
+                "summary" : "say hi"
+             }
+          }
+       },
+       "openapi" : "3.0.0",
+       "info" : {
+          "version" : "1.0",
+          "title" : "Path-Altering Reverse Proxy Example"
+       }
+    }
+

examples/openapi3/reverseproxy_aiohttp/app.py

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+#!/usr/bin/env python3
+'''
+example of aiohttp connexion running behind a path-altering reverse-proxy
+'''
+
+import json
+import connexion
+from yarl import URL
+from aiohttp import web
+from aiohttp_remotes.x_forwarded import XForwardedBase
+from aiohttp_remotes.exceptions import RemoteError, TooManyHeaders
+
+X_FORWARDED_PATH = "X-Forwarded-Path"
+
+
+class XPathForwarded(XForwardedBase):
+
+    def __init__(self, num=1):
+        self._num = num
+
+    def get_forwarded_path(self, headers):
+        forwarded_host = headers.getall(X_FORWARDED_PATH, [])
+        if len(forwarded_host) > 1:
+            raise TooManyHeaders(X_FORWARDED_PATH)
+        return forwarded_host[0] if forwarded_host else None
+
+    @web.middleware
+    async def middleware(self, request, handler):
+        try:
+            overrides = {}
+            headers = request.headers
+
+            forwarded_for = self.get_forwarded_for(headers)
+            if forwarded_for:
+                overrides['remote'] = str(forwarded_for[-self._num])
+
+            proto = self.get_forwarded_proto(headers)
+            if proto:
+                overrides['scheme'] = proto[-self._num]
+
+            host = self.get_forwarded_host(headers)
+            if host is not None:
+                overrides['host'] = host
+
+            prefix = self.get_forwarded_path(headers)
+            if prefix is not None:
+                prefix = '/' + prefix.strip('/') + '/'
+                request_path = URL(request.path.lstrip('/'))
+                overrides['rel_url'] = URL(prefix).join(request_path)
+
+            request = request.clone(**overrides)
+
+            return await handler(request)
+        except RemoteError as exc:
+            exc.log(request)
+        await self.raise_error(request)
+
+
+def hello(request):
+    ret = {
+        "host": request.host,
+        "scheme": request.scheme,
+        "path": request.path,
+        "_href": str(request.url)
+    }
+    return web.Response(text=json.dumps(ret), status=200)
+
+
+if __name__ == '__main__':
+    app = connexion.AioHttpApp(__name__)
+    app.add_api('openapi.yaml', pass_context_arg_name='request')
+    aio = app.app
+    reverse_proxied = XPathForwarded()
+    aio.middlewares.append(reverse_proxied.middleware)
+    app.run(port=8080)

examples/openapi3/reverseproxy_aiohttp/nginx.conf

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+worker_processes 1;
+error_log stderr;
+daemon off;
+pid nginx.pid;
+
+events {
+  worker_connections  1024;
+}
+
+http {
+  include             /etc/nginx/mime.types;
+  default_type        application/octet-stream;
+
+  sendfile on;
+
+  keepalive_timeout   65;
+
+  ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
+  ssl_prefer_server_ciphers on;
+  access_log access.log;
+  server {
+
+        listen localhost:9000;
+
+        location /reverse_proxied/ {
+          # Define the location of the proxy server to send the request to
+          proxy_pass http://localhost:8080/;
+          # Add prefix header
+          proxy_set_header X-Forwarded-Path /reverse_proxied/;
+          proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+          proxy_set_header X-Forwarded-Host   $host:$server_port;
+          proxy_set_header X-Forwarded-Server $host;
+          proxy_set_header X-Forwarded-Port   $server_port;
+          proxy_set_header X-Forwarded-Proto  http;
+        }
+
+  }
+}

examples/openapi3/reverseproxy_aiohttp/openapi.yaml

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+openapi: 3.0.0
+info:
+  title: Path-Altering Reverse Proxy Example
+  version: '1.0'
+servers:
+  - url: /api
+paths:
+  /hello:
+    get:
+      summary: say hi
+      operationId: app.hello
+      responses:
+        '200':
+          description: hello
+          content:
+            text/plain:
+              schema:
+                type: string