docs: how to make Keptn work with vCluster (#2382)

Signed-off-by: Meg McRoberts <[email protected]>
Co-authored-by: Moritz Wiesinger <[email protected]>

README.md

@@ -66,8 +66,12 @@ The status follows the
 
 Keptn can be installed on any Kubernetes cluster
 running Kubernetes >=1.24.
-Note that Keptn is not currently compatible with
-[vcluster](https://github.com/loft-sh/vcluster).
+
+For users running [vCluster](https://www.vcluster.com/),
+please note that you may need to modify
+your configuration before installing Keptn; see
+[Running Keptn with vCluster](https://main.lifecycle.keptn.sh/docs/install/install//#running-keptn-with-vcluster)
+for more information.
 
 Use the following command sequence
 to install the latest release of Keptn:

docs/content/en/docs/install/install.md

@@ -30,6 +30,34 @@ in order to run some Keptn functionality.
 You are then ready to
 [Integrate Keptn with your applications](../implementing/integrate).
 
+## Running Keptn with vCluster
+
+Keptn running on Kubernetes versions 1.26 and older
+uses a custom
+[scheduler](../architecture/components/scheduler/),
+so it does not work with
+[Virtual Kubernetes Clusters](https://www.vcluster.com/)
+("vClusters") out of the box.
+This is also an issue
+if the `schedulingGatesEnabled` Helm chart value is set to `false`
+for Kubernetes version 1.27 and later.
+See
+[Keptn integration with Scheduling](../architecture/components/scheduler/)
+for details.
+
+To solve this problem:
+
+1. Follow the instructions in
+   [Separate vCluster Scheduler](https://www.vcluster.com/docs/architecture/scheduling#separate-vcluster-scheduler)
+   to modify the vCluster `values.yaml` file
+   to use a virtual scheduler.
+
+1. Create or upgrade the vCluster,
+   following the instructions in that same document.
+
+1. Follow the instructions in the section below
+   to install Keptn in that vCluster.
+
 ## Use Helm Chart
 
 Version v0.7.0 and later of Keptn

docs/content/en/docs/install/reqs.md

@@ -24,8 +24,22 @@ Kustomize Version: v4.5.4
 Server Version: v1.24.0
 ```
 
-Keptn is not currently compatible with
-[vcluster](<https://github.com/loft-sh/vcluster>).
+Keptn makes use of a custom scheduler
+when running on Kubernetes v1.26 and earlier.
+For Kubernetes v1.27 and later, scheduling is
+implemented using
+[Kubernetes scheduling gates](https://kubernetes.io/docs/concepts/scheduling-eviction/pod-scheduling-readiness/),
+unless the `schedulingGatesEnabled` Helm value is set to `false`.
+See
+[Keptn integration with Scheduling](../architecture/components/scheduler/)
+for details.
+
+If Keptn is installed on a [vCluster](https://www.vcluster.com/) with
+Kubernetes v1.26 or earlier, some extra configuration
+needs to be added for full compatibility.
+See
+[Running Keptn with vCluster](install.md/#running-keptn-with-vcluster)
+for more information.
 
 ## Resource requirements