Add an option to override the external URL scheme

tutor/cli.py

@@ -45,13 +45,15 @@ def main(ctx, database, log_level):
 
 @main.command()
 @click.option("--port", type=int, envvar="TUTOR_PORT", default=8888)
+@click.option("--scheme", envvar="TUTOR_SCHEME")
 @click.option("--static", envvar="TUTOR_STATIC", type=click.Path(file_okay=False))
 @click.option("--debug", is_flag=True)
 @click.pass_context
-def server(ctx, port, static, debug):
+def server(ctx, port, scheme, static, debug):
     app = tutor.server.make_app(
         {
             **ctx.obj,
+            "scheme": scheme,
             "static": static,
             "debug": debug,
         }

tutor/server.py

@@ -30,10 +30,27 @@ def update_args(url: str, **qargs) -> str:
 
 
 class SearchHandler(tornado.web.RequestHandler):
+    def url(self, url: str) -> str:
+        scheme_override = self.application.settings["scheme"]
+        if not scheme_override:
+            return url
+        parts = urllib.parse.urlsplit(url)
+        return urllib.parse.urlunsplit(
+            (
+                scheme_override,
+                parts.netloc,
+                parts.path,
+                parts.query,
+                parts.fragment,
+            )
+        )
+
     def set_links(self, **links) -> None:
         self.set_header(
             "Link",
-            ", ".join([f'<{url}>; rel="{rel}"' for rel, url in links.items()]),
+            ", ".join(
+                [f'<{self.url(url)}>; rel="{rel}"' for rel, url in links.items()]
+            ),
         )
 
     async def get(self) -> None: