Soft transition to modern app.kubernetes.io labels

Author: consideRatio

kubespawner/proxy.py

@@ -156,14 +156,21 @@ def _namespace_default(self):
         'singleuser-server',
         config=True,
         help="""
-        The component label used to tag the user pods. This can be used to override
-        the spawner behavior when dealing with multiple hub instances in the same
-        namespace. Usually helpful for CI workflows.
+        The value of the labels app.kubernetes.io/component and component, used
+        to identify user pods kubespawner is to manage.
+
+        This can be used to override the spawner behavior when dealing with
+        multiple hub instances in the same namespace. Usually helpful for CI
+        workflows.
         """,
     )
 
     common_labels = Dict(
         {
+            'app.kubernetes.io/name': 'jupyterhub',
+            'app.kubernetes.io/managed-by': 'kubespawner',
+            # app and heritage are older variants of the modern
+            # app.kubernetes.io labels
             'app': 'jupyterhub',
             'heritage': 'jupyterhub',
         },
@@ -320,6 +327,7 @@ def __init__(self, *args, **kwargs):
         self.networking_api = shared_client('NetworkingV1Api')
 
         labels = {
+            'app.kubernetes.io/component': self.component_label,
             'component': self.component_label,
             'hub.jupyter.org/proxy-route': 'true',
         }
@@ -421,7 +429,12 @@ async def add_route(self, routespec, target, data):
         full_name = f'{self.namespace}/{safe_name}'
 
         common_labels = self._expand_all(self.common_labels, routespec, data)
-        common_labels.update({'component': self.component_label})
+        common_labels.update(
+            {
+                'app.kubernetes.io/component': self.component_label,
+                'component': self.component_label,
+            }
+        )
 
         ingress_extra_labels = self._expand_all(
             self.ingress_extra_labels, routespec, data

kubespawner/spawner.py

@@ -596,9 +596,12 @@ def _namespace_default(self):
         'singleuser-server',
         config=True,
         help="""
-        The component label used to tag the user pods. This can be used to override
-        the spawner behavior when dealing with multiple hub instances in the same
-        namespace. Usually helpful for CI workflows.
+        The value of the labels app.kubernetes.io/component and component, used
+        to identify user pods kubespawner is to manage.
+
+        This can be used to override the spawner behavior when dealing with
+        multiple hub instances in the same namespace. Usually helpful for CI
+        workflows.
         """,
     )
 
@@ -655,6 +658,10 @@ def _deprecated_changed(self, change):
 
     common_labels = Dict(
         {
+            'app.kubernetes.io/name': 'jupyterhub',
+            'app.kubernetes.io/managed-by': 'kubespawner',
+            # app and heritage are older variants of the modern
+            # app.kubernetes.io labels
             'app': 'jupyterhub',
             'heritage': 'jupyterhub',
         },
@@ -1878,6 +1885,7 @@ def _build_pod_labels(self, extra_labels):
         labels = self._build_common_labels(extra_labels)
         labels.update(
             {
+                'app.kubernetes.io/component': self.component_label,
                 'component': self.component_label,
                 'hub.jupyter.org/servername': escapism.escape(
                     self.name, safe=self.safe_chars, escape_char='-'
@@ -2102,7 +2110,17 @@ def get_pvc_manifest(self):
         Make a pvc manifest that will spawn current user's pvc.
         """
         labels = self._build_common_labels(self._expand_all(self.storage_extra_labels))
-        labels.update({'component': 'singleuser-storage'})
+        labels.update(
+            {
+                # The component label has been set to singleuser-storage, but should
+                # probably have been set to singleuser-server (self.component_label)
+                # as that ties it to the user pods kubespawner creates. Due to that,
+                # the newly introduced label app.kubernetes.io/component gets
+                # singleuser-server (self.component_label) as a value instead.
+                'app.kubernetes.io/component': self.component_label,
+                'component': 'singleuser-storage',
+            }
+        )
 
         annotations = self._build_common_annotations(
             self._expand_all(self.storage_extra_annotations)
@@ -2473,6 +2491,14 @@ async def _start_watching_pods(self, replace=False):
         return await self._start_reflector(
             kind="pods",
             reflector_class=PodReflector,
+            # NOTE: We monitor pods with the old component label instead of the
+            #       modern app.kubernetes.io/component label. A change here is
+            #       only non-breaking if we can assume the running pods we want
+            #       to monitor can be detected by either the old or modern
+            #       label.
+            #
+            #       Related to https://github.com/jupyterhub/kubespawner/issues/834
+            #
             labels={"component": self.component_label},
             omit_namespace=self.enable_user_namespaces,
             replace=replace,