Merge pull request #37224 from pwschuurman/kep-3335-documentation

Add initial documentation for StatefulSetSlice feature

content/en/docs/concepts/workloads/controllers/statefulset.md

@@ -154,8 +154,23 @@ regardless of which node it's (re)scheduled on.
 
 ### Ordinal Index
 
-For a StatefulSet with N replicas, each Pod in the StatefulSet will be
-assigned an integer ordinal, from 0 up through N-1, that is unique over the Set.
+For a StatefulSet with N [replicas](#replicas), each Pod in the StatefulSet
+will be assigned an integer ordinal, that is unique over the Set. By default,
+pods will be assigned ordinals from 0 up through N-1.
+
+### Start ordinal
+
+{{< feature-state for_k8s_version="v1.26" state="alpha" >}}
+
+`.spec.ordinals` is an optional field that allows you to configure the integer
+ordinals assigned to each Pod. It defaults to nil. You must enable the
+`StatefulSetStartOrdinal`
+[feature gate](/docs/reference/command-line-tools-reference/feature-gates/) to
+use this field. Once enabled, you can configure the following options:
+
+* `.spec.ordinals.start`: If the `.spec.ordinals.start` field is set, Pods will
+  be assigned ordinals from `.spec.ordinals.start` up through
+  `.spec.ordinals.start + .spec.replicas - 1`.
 
 ### Stable Network ID
 

content/en/docs/reference/command-line-tools-reference/feature-gates.md

@@ -181,6 +181,7 @@ For a reference to old feature gates that are removed, please refer to
 | `SizeMemoryBackedVolumes` | `false` | Alpha | 1.20 | 1.21 |
 | `SizeMemoryBackedVolumes` | `true` | Beta | 1.22 | |
 | `StatefulSetAutoDeletePVC` | `false` | Alpha | 1.22 | |
+| `StatefulSetStartOrdinal` | `false` | Alpha | 1.26 | |
 | `StorageVersionAPI` | `false` | Alpha | 1.20 | |
 | `StorageVersionHash` | `false` | Alpha | 1.14 | 1.14 |
 | `StorageVersionHash` | `true` | Beta | 1.15 | |
@@ -751,6 +752,10 @@ Each feature gate is designed for enabling/disabling a specific feature:
   memory-backed volumes (mainly `emptyDir` volumes).
 - `StatefulSetMinReadySeconds`: Allows `minReadySeconds` to be respected by
   the StatefulSet controller.
+- `StatefulSetStartOrdinal`: Allow configuration of the start ordinal in a
+  StatefulSet. See
+  [Start ordinal](/docs/concepts/workloads/controllers/statefulset/#start-ordinal)
+  for more details.
 - `StorageVersionAPI`: Enable the
   [storage version API](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#storageversion-v1alpha1-internal-apiserver-k8s-io).
 - `StorageVersionHash`: Allow API servers to expose the storage version hash in the

content/en/docs/tutorials/stateful-application/basic-stateful-set.md

@@ -131,6 +131,11 @@ Notice that the `web-1` Pod is not launched until the `web-0` Pod is
 _Running_ (see [Pod Phase](/docs/concepts/workloads/pods/pod-lifecycle/#pod-phase))
 and _Ready_ (see `type` in [Pod Conditions](/docs/concepts/workloads/pods/pod-lifecycle/#pod-conditions)).
 
+{{< note >}}
+To configure the integer ordinal assigned to each Pod in a StatefulSet, see
+[Start ordinal](/docs/concepts/workloads/controllers/statefulset/#start-ordinal).
+{{< /note >}}
+
 ## Pods in a StatefulSet
 
 Pods in a StatefulSet have a unique ordinal index and a stable network identity.