Allow volumes and volume mounts to be defined as Dicts

Continue to support these values to be defined as Lists for backwards compatibility.

When defined as Dicts, the items are sorted lexicographically by the keys and the values are used as volumes / volume mounts.

This enables easy overriding or extension. refs NASA-IMPACT/veda-jupyterhub#44 (comment) jupyterhub/jupyterhub#4822

kubespawner/spawner.py

@@ -1033,14 +1033,25 @@ def _validate_image_pull_secrets(self, proposal):
         """,
     )
 
-    volumes = List(
+    volumes = Union(
+        trait_types=[
+            List(),
+            Dict(),
+        ],
         config=True,
         help="""
-        List of Kubernetes Volume specifications that will be mounted in the user pod.
+        List of Kubernetes Volume specifications that will be mounted in the user pod,
+        or a dictionary where the values specify the volume specifications.
 
-        This list will be directly added under `volumes` in the kubernetes pod spec,
-        so you should use the same structure. Each item in the list must have the
-        following two keys:
+        If provided as a list, this list will be directly added under `volumes` in
+        the kubernetes pod spec
+
+        If provided as a dictionary, the items will be sorted lexicographically by the dictionary keys
+        and then the sorted values will be added to the `volumes` key. The keys of the
+        dictionary can be any descriptive name for the volume specification.
+
+        Each item (whether in the list or dictionary values) must be a dictionary with
+        the following two keys:
 
           - `name`
             Name that'll be later used in the `volume_mounts` config to mount this
@@ -1063,14 +1074,25 @@ def _validate_image_pull_secrets(self, proposal):
         """,
     )
 
-    volume_mounts = List(
+    volume_mounts = Union(
+        trait_types=[
+            List(),
+            Dict(),
+        ],
         config=True,
         help="""
-        List of paths on which to mount volumes in the user notebook's pod.
+        List of paths on which to mount volumes in the user notebook's pod, or a dictionary
+        where the values specify the paths to mount the volumes.
+
+        If provided as a list, this list will be added directly to the values of the
+        `volumeMounts` key under the user's container in the kubernetes pod spec.
+
+        If provided as a dictionary, the items will be sorted lexicographically by the dictionary keys and
+        then the sorted values will be added to the `volumeMounts` key. The keys of the
+        dictionary can be any descriptive name for the volume mount.
 
-        This list will be added to the values of the `volumeMounts` key under the user's
-        container in the kubernetes pod spec, so you should use the same structure as that.
-        Each item in the list should be a dictionary with at least these two keys:
+        Each item (whether in the list or dictionary values) should be a dictionary with
+        at least these two keys:
 
            - `mountPath` The path on the container in which we want to mount the volume.
            - `name` The name of the volume we want to mount, as specified in the `volumes` config.
@@ -1869,6 +1891,12 @@ def _expand_all(self, src):
         else:
             return src
 
+    def _sorted_dict_values(self, src):
+        if isinstance(src, dict):
+            return [src[key] for key in sorted(src.keys())]
+        else:
+            return src
+
     def _build_common_labels(self, extra_labels):
         # Default set of labels, picked up from
         # https://github.com/helm/helm-www/blob/HEAD/content/en/docs/chart_best_practices/labels.md
@@ -2032,8 +2060,8 @@ async def get_pod_manifest(self):
             container_security_context=csc,
             pod_security_context=psc,
             env=self.get_env(),  # Expansion is handled by get_env
-            volumes=self._expand_all(self.volumes),
-            volume_mounts=self._expand_all(self.volume_mounts),
+            volumes=self._expand_all(self._sorted_dict_values(self.volumes)),
+            volume_mounts=self._expand_all(self._sorted_dict_values(self.volume_mounts)),
             working_dir=self.working_dir,
             labels=labels,
             annotations=annotations,

tests/test_spawner.py

@@ -1798,3 +1798,115 @@ async def test_ipv6_addr():
     )
     url = spawner._get_pod_url({"status": {"podIP": "cafe:f00d::"}})
     assert "[" in url and "]" in url
+
+
+async def test_volume_mount_dictionary():
+    """
+    Test that volume_mounts can be a dictionary of dictionaries.
+    The output list should be lexicographically sorted by key.
+    """
+    c = Config()
+
+    c.KubeSpawner.volume_mounts = {
+        "02-group-beta": {
+            'name': 'volume-mounts-beta',
+            'mountPath': '/beta/',
+        },
+        "01-group-alpha": {
+            'name': 'volume-mounts-alpha',
+            'mountPath': '/alpha/',
+        },
+    }
+
+    spawner = KubeSpawner(config=c, _mock=True)
+
+    manifest = await spawner.get_pod_manifest()
+
+    assert isinstance(manifest.spec.containers[0].volume_mounts, list)
+    assert manifest.spec.containers[0].volume_mounts[0].name == 'volume-mounts-alpha'
+    assert manifest.spec.containers[0].volume_mounts[0].mount_path == '/alpha/'
+    assert manifest.spec.containers[0].volume_mounts[1].name == 'volume-mounts-beta'
+    assert manifest.spec.containers[0].volume_mounts[1].mount_path == '/beta/'
+
+
+async def test_volume_mount_list():
+    """
+    Test that volume_mounts can be a list of dictionaries for backwards compatibility.
+    """
+    c = Config()
+
+    c.KubeSpawner.volume_mounts = [
+        {
+            'name': 'volume-mounts-alpha',
+            'mountPath': '/alpha/',
+        },
+        {
+            'name': 'volume-mounts-beta',
+            'mountPath': '/beta/',
+        },
+    ]
+    spawner = KubeSpawner(config=c, _mock=True)
+
+    manifest = await spawner.get_pod_manifest()
+
+    assert isinstance(manifest.spec.containers[0].volume_mounts, list)
+    assert manifest.spec.containers[0].volume_mounts[0].name == 'volume-mounts-alpha'
+    assert manifest.spec.containers[0].volume_mounts[0].mount_path == '/alpha/'
+    assert manifest.spec.containers[0].volume_mounts[1].name == 'volume-mounts-beta'
+    assert manifest.spec.containers[0].volume_mounts[1].mount_path == '/beta/'
+
+
+async def test_volume_dict():
+    """
+    Test that volumes can be a dictionary of dictionaries.
+    The output list should be lexicographically sorted by key.
+    """
+    c = Config()
+
+    c.KubeSpawner.volumes = {
+        "02-group-beta": {
+            'name': 'volumes-beta',
+            'persistentVolumeClaim': {'claimName': 'beta-claim'},
+        },
+        "01-group-alpha": {
+            'name': 'volumes-alpha',
+            'persistentVolumeClaim': {'claimName': 'alpha-claim'},
+        },
+    }
+
+    spawner = KubeSpawner(config=c, _mock=True)
+
+    manifest = await spawner.get_pod_manifest()
+
+    assert isinstance(manifest.spec.volumes, list)
+    assert manifest.spec.volumes[0].name == 'volumes-alpha'
+    assert manifest.spec.volumes[0].persistent_volume_claim["claimName"] == 'alpha-claim'
+    assert manifest.spec.volumes[1].name == 'volumes-beta'
+    assert manifest.spec.volumes[1].persistent_volume_claim["claimName"] == 'beta-claim'
+
+
+async def test_volume_list():
+    """
+    Test that volumes can be a list of dictionaries for backwards compatibility.
+    """
+    c = Config()
+
+    c.KubeSpawner.volumes = [
+        {
+            'name': 'volumes-alpha',
+            'persistentVolumeClaim': {'claimName': 'alpha-claim'},
+        },
+        {
+            'name': 'volumes-beta',
+            'persistentVolumeClaim': {'claimName': 'beta-claim'},
+        },
+    ]
+    spawner = KubeSpawner(config=c, _mock=True)
+
+    manifest = await spawner.get_pod_manifest()
+
+    assert isinstance(manifest.spec.volumes, list)
+    assert manifest.spec.volumes[0].name == 'volumes-alpha'
+    assert manifest.spec.volumes[0].persistent_volume_claim["claimName"] == 'alpha-claim'
+    assert manifest.spec.volumes[1].name == 'volumes-beta'
+    assert manifest.spec.volumes[1].persistent_volume_claim["claimName"] == 'beta-claim'