Add abilty to configure postStart handler for teleport-cluster chart

docs/pages/kubernetes-access/helm/reference.mdx

@@ -951,6 +951,29 @@ A list of `initContainers` which will be run before the main Teleport container
   </TabItem>
 </Tabs>
 
+## `postStart`
+
+[Kubernetes reference](https://kubernetes.io/docs/tasks/configure-pod-container/attach-handler-lifecycle-event/)
+
+A `postStart` lifecycle handler to be configured on the main Teleport container.
+
+<Tabs>
+  <TabItem label="values.yaml">
+  ```yaml
+  postStart:
+    command:
+    - echo
+    - foo
+  ```
+  </TabItem>
+  <TabItem label="--set">
+  ```shell
+  --set "postStart.command[0]=echo" \
+  --set "postStart.command[1]=foo"
+  ```
+  </TabItem>
+</Tabs>
+
 ## `resources`
 
 | Type | Default value | Can be used in `custom` mode? |

examples/chart/teleport-cluster/templates/deployment.yaml

@@ -136,6 +136,12 @@ spec:
           initialDelaySeconds: 5 # wait 5s for agent to register
           periodSeconds: 5 # poll health every 5s
           failureThreshold: 12 # consider agent unhealthy after 60s (12 * 5s)
+{{- if .Values.postStart.command }}
+        lifecycle:
+          postStart:
+            exec:
+              command: {{ toYaml .Values.postStart.command | nindent 14 }}
+{{- end }}
 {{- if .Values.resources }}
         resources:
   {{- toYaml .Values.resources | nindent 10 }}

examples/chart/teleport-cluster/values.schema.json

@@ -318,6 +318,20 @@
             "type": "array",
             "default": []
         },
+        "postStart": {
+            "$id": "#/properties/postStart",
+            "type": "object",
+            "required": [
+                "command"
+            ],
+            "properties": {
+                "command": {
+                    "$id": "#properties/postStart/command",
+                    "type": "array",
+                    "default": []
+                }
+            }
+        },
         "kubeClusterName": {
             "$id": "#/properties/kubeClusterName",
             "type": "string",

examples/chart/teleport-cluster/values.yaml

@@ -203,6 +203,11 @@ initContainers: []
 #  image: "alpine"
 #  args: ["echo test"]
 
+# If set, will run the command as a postStart handler
+# https://kubernetes.io/docs/tasks/configure-pod-container/attach-handler-lifecycle-event/
+postStart:
+  command: []
+
 # Resources to request for each pod in the deployment
 # https://kubernetes.io/docs/concepts/configuration/manage-resources-containers/
 resources: {}