persist spawner.port in pod annotations

avoids changes to self.port (e.g. dynamic or changed config)
being interpreted as a changed URL for a running pod

Author: minrk

kubespawner/spawner.py

@@ -2230,11 +2230,21 @@ def _get_pod_url(self, pod):
                     for s in self.pod_connect_ip.split(".")
                 ]
             )
+        # extract port from pod manifest
+        port_str = pod["metadata"]["annotations"].get("hub.jupyter.org/port")
+        if port_str:
+            port = int(port_str)
+        else:
+            # this should only happend
+            self.log.warning(
+                f"Pod {pod['metadata']['name']} missing annotation 'hub.jupyter.org/port'"
+            )
+            port = self.port
 
         return "{}://{}:{}".format(
             proto,
             hostname,
-            self.port,
+            port,
         )
 
     async def get_pod_manifest(self):
@@ -2285,6 +2295,7 @@ async def get_pod_manifest(self):
         annotations = self._build_common_annotations(
             self._expand_all(self.extra_annotations)
         )
+        annotations["hub.jupyter.org/port"] = str(self.port)
 
         return make_pod(
             name=self.pod_name,

tests/test_spawner.py

@@ -1853,6 +1853,18 @@ async def test_url_changed(kube_ns, kube_client, config, hub_pod, hub):
     await spawner.poll()
     assert spawner.db.commit.call_count == previous_commit_count
 
+    # changing spawner.port (e.g. updated config while pod is running)
+    # should _not_ indicate changed url of running pod
+    spawner.port = 1234
+    await spawner.poll()
+    ref_key = f"{spawner.namespace}/{spawner.pod_name}"
+    pod = spawner.pod_reflector.pods.get(ref_key, None)
+    assert pod["metadata"]["annotations"]["hub.jupyter.org/port"] == "8888"
+    url = spawner._get_pod_url(pod)
+    assert url == pod_host
+    # didn't commit to the db
+    assert spawner.db.commit.call_count == previous_commit_count
+
     await spawner.stop()
 
 
@@ -1917,7 +1929,9 @@ async def test_ipv6_addr():
     spawner = KubeSpawner(
         _mock=True,
     )
-    url = spawner._get_pod_url({"status": {"podIP": "cafe:f00d::"}})
+    url = spawner._get_pod_url(
+        {"metadata": {"annotations": {}}, "status": {"podIP": "cafe:f00d::"}}
+    )
     assert "[" in url and "]" in url