Add redirect from prefix root to status (#9015)

Author: icykip

distributed/dashboard/scheduler.py

@@ -172,15 +172,23 @@ def connect(application, http_server, scheduler, prefix=""):
     application.add_application(bokeh_app)
     bokeh_app.initialize(IOLoop.current())
 
-    bokeh_app.add_handlers(
-        r".*",
-        [
+    routes = [
+        (
+            r"/",
+            web.RedirectHandler,
+            {"url": urljoin((prefix or "").strip("/") + "/", "status")},
+        )
+    ]
+
+    if prefix:
+        prefix_clean = prefix.strip("/")
+        routes.append(
             (
-                r"/",
+                rf"/{prefix_clean}/?",
                 web.RedirectHandler,
-                {"url": urljoin((prefix or "").strip("/") + "/", r"status")},
+                {"url": urljoin(prefix_clean + "/", "status")},
             )
-        ],
-    )
+        )
 
+    bokeh_app.add_handlers(r".*", routes)
     bokeh_app.start()

distributed/dashboard/tests/test_scheduler_bokeh.py

@@ -1329,6 +1329,23 @@ async def test_prefix_bokeh(s, a, b):
     assert bokeh_app.prefix == f"/{prefix}"
 
 
+@gen_cluster(
+    client=True, scheduler_kwargs={"http_prefix": "foo-bar", "dashboard": True}
+)
+async def test_prefix_redirect_bokeh(c, s, a, b):
+    prefix = "foo-bar"
+    http_client = AsyncHTTPClient()
+    response = await http_client.fetch(
+        f"http://localhost:{s.http_server.port}/{prefix}"
+    )
+    assert response.code == 200
+    assert "/status" in response.effective_url
+
+    bokeh_app = s.http_application.applications[0]
+    assert isinstance(bokeh_app, BokehTornado)
+    assert bokeh_app.prefix == f"/{prefix}"
+
+
 @gen_cluster(scheduler_kwargs={"dashboard": True})
 async def test_bokeh_relative(s, a, b):
     http_client = AsyncHTTPClient()