Add composite application helper

examples/vhost.py

@@ -0,0 +1,36 @@
+"""
+A server that implements virtual hosting for multiple subdomains.
+
+This is a basic example of you how can run multiple apps from the same server
+by creating a composite application.
+
+> jetforce-client gemini://apple.localhost --host localhost
+> jetforce-client gemini://banana.localhost --host localhost
+"""
+from jetforce import GeminiServer, JetforceApplication, Response, Status
+from jetforce.app.composite import CompositeApplication
+
+apple = JetforceApplication()
+
+
+@apple.route()
+def index(request):
+    return Response(Status.SUCCESS, "text/plain", "apple!")
+
+
+banana = JetforceApplication()
+
+
+@banana.route()
+def index(request):
+    return Response(Status.SUCCESS, "text/plain", "banana!")
+
+
+composite_app = CompositeApplication(
+    {"apple.localhost": apple, "banana.localhost": banana}
+)
+
+
+if __name__ == "__main__":
+    server = GeminiServer(composite_app)
+    server.run()

examples/virtualhost.py

@@ -1,31 +0,0 @@
-"""
-This is an example of using virtual hosting to serve URLs for multiple
-subdomains from a single jetforce server.
-"""
-import asyncio
-
-import jetforce
-from jetforce import Response, Status
-
-app = jetforce.JetforceApplication()
-
-
-@app.route(hostname="apple.localhost")
-def serve_apple_domain(request):
-    return Response(Status.SUCCESS, "text/plain", f"apple\n{request.path}")
-
-
-@app.route(hostname="banana.localhost")
-def serve_banana_domain(request):
-    return Response(Status.SUCCESS, "text/plain", f"banana\n{request.path}")
-
-
-if __name__ == "__main__":
-    args = jetforce.command_line_parser().parse_args()
-    ssl_context = jetforce.make_ssl_context(
-        args.hostname, args.certfile, args.keyfile, args.cafile, args.capath
-    )
-    server = jetforce.GeminiServer(
-        host=args.host, port=args.port, ssl_context=ssl_context, app=app
-    )
-    asyncio.run(server.run())

jetforce/app/composite.py

@@ -0,0 +1,50 @@
+import typing
+
+from .base import Request, Status
+
+
+class CompositeApplication:
+    """
+    Route requests between multiple applications by looking at the URL hostname.
+
+    The primary intention of this class is enable virtual hosting by serving
+    two or more applications behind a single jetforce server.
+    """
+
+    def __init__(self, application_map: typing.Dict[typing.Optional[str], typing.Any]):
+        """
+        Initialize the application by providing a mapping of hostname -> app
+        key pairs. A hostname of `None` is a special key that can be used as
+        a default if none of the others match.
+
+        Example:
+            app = CompositeApplication(
+                {
+                    "cats.com": cats_app,
+                    "dogs.com": dogs_app,
+                    None: other_animals_app,
+                }
+            )
+        """
+        self.application_map = application_map
+
+    def __call__(
+        self, environ: dict, send_status: typing.Callable
+    ) -> typing.Iterator[bytes]:
+        try:
+            request = Request(environ)
+        except Exception:
+            send_status(Status.BAD_REQUEST, "Unrecognized URL format")
+            return
+
+        if request.hostname in self.application_map:
+            environ["HOSTNAME"] = request.hostname
+            app = self.application_map[request.hostname]
+            yield from app(environ, send_status)
+
+        elif None in self.application_map:
+            app = self.application_map[None]
+            yield from app(environ, send_status)
+
+        else:
+            send_status(Status.PROXY_REQUEST_REFUSED, "Invalid hostname")