From 20c6f1e32ff17b5b9381765540473a7201340e28 Mon Sep 17 00:00:00 2001
From: Meg McRoberts <meg.mcroberts@dynatrace.com>
Date: Tue, 31 Oct 2023 06:13:18 -0700
Subject: [PATCH] docs: how to make Keptn work with vCluster (#2382)

Signed-off-by: Meg McRoberts <meg.mcroberts@dynatrace.com>
Co-authored-by: Moritz Wiesinger <moritz.wiesinger@dynatrace.com>
---
 README.md                               |  8 +++++--
 docs/content/en/docs/install/install.md | 28 +++++++++++++++++++++++++
 docs/content/en/docs/install/reqs.md    | 18 ++++++++++++++--
 3 files changed, 50 insertions(+), 4 deletions(-)

diff --git a/README.md b/README.md
index 39b4e9427a..4309df9a68 100644
--- a/README.md
+++ b/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:
diff --git a/docs/content/en/docs/install/install.md b/docs/content/en/docs/install/install.md
index 113da079c5..62ba2ef0cc 100644
--- a/docs/content/en/docs/install/install.md
+++ b/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
diff --git a/docs/content/en/docs/install/reqs.md b/docs/content/en/docs/install/reqs.md
index db4f436b0e..d6c843692a 100644
--- a/docs/content/en/docs/install/reqs.md
+++ b/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