docs: Added notice for incompatibility with kubernetes 1.26 (aws#4103)

Co-authored-by: Brandon Wagner <[email protected]>

website/content/en/docs/upgrade-guide.md

@@ -103,6 +103,11 @@ Snapshot releases are tagged with the git commit hash prefixed by the Karpenter
 ## Released Upgrade Notes
 
 ### Upgrading to v0.28.0+
+
+{{% alert title="Warning" color="warning" %}}
+Karpenter v0.28.0 is incompatible with Kubernetes version 1.26+, which can result in additional node scale outs when using `--cloudprovider=external`, which is the default for the EKS Optimized AMI. See: https://github.com/aws/karpenter-core/pull/375
+{{% /alert %}}
+
 * The `extraObjects` value is now removed from the Helm chart. Having this value in the chart proved to not work in the majority of Karpenter installs and often led to anti-patterns, where the Karpenter resources installed to manage Karpenter's capacity were directly tied to the install of the Karpenter controller deployments. The Karpenter team recommends that, if you want to install Karpenter manifests alongside the Karpenter helm chart, to do so by creating a separate chart for the manifests, creating a dependency on the controller chart.
 * The `aws.nodeNameConvention` setting is now removed from the [`karpenter-global-settings`]({{<ref "./concepts/settings#configmap" >}}) ConfigMap. Because Karpenter is now driving its orchestration of capacity through Machines, it no longer needs to know the node name, making this setting obsolete. Karpenter ignores configuration that it doesn't recognize in the [`karpenter-global-settings`]({{<ref "./concepts/settings#configmap" >}}) ConfigMap, so leaving the `aws.nodeNameConvention` in the ConfigMap will simply cause this setting to be ignored.
 * Karpenter now defines a set of "restricted tags" which can't be overridden with custom tagging in the AWSNodeTemplate or in the [`karpenter-global-settings`]({{<ref "./concepts/settings#configmap" >}}) ConfigMap. If you are currently using any of these tag overrides when tagging your instances, webhook validation will now fail. These tags include:

website/content/en/preview/upgrade-guide.md

@@ -106,6 +106,11 @@ Snapshot releases are tagged with the git commit hash prefixed by the Karpenter
 * Karpenter has changed the default metrics service port from 8080 to 8000. In `v0.28.0`, the Karpenter pod port was changed to 8000, but referenced the service by name, allowing users to scrape the service at port 8080 for metrics. `v0.29.0` aligns the two ports so that default service and default pod metrics ports are the same.
 
 ### Upgrading to v0.28.0+
+
+{{% alert title="Warning" color="warning" %}}
+Karpenter v0.28.0 is incompatible with Kubernetes version 1.26+, which can result in additional node scale outs when using `--cloudprovider=external`, which is the default for the EKS Optimized AMI. See: https://github.com/aws/karpenter-core/pull/375
+{{% /alert %}}
+
 * The `extraObjects` value is now removed from the Helm chart. Having this value in the chart proved to not work in the majority of Karpenter installs and often led to anti-patterns, where the Karpenter resources installed to manage Karpenter's capacity were directly tied to the install of the Karpenter controller deployments. The Karpenter team recommends that, if you want to install Karpenter manifests alongside the Karpenter helm chart, to do so by creating a separate chart for the manifests, creating a dependency on the controller chart.
 * The `aws.nodeNameConvention` setting is now removed from the [`karpenter-global-settings`]({{<ref "./concepts/settings#configmap" >}}) ConfigMap. Because Karpenter is now driving its orchestration of capacity through Machines, it no longer needs to know the node name, making this setting obsolete. Karpenter ignores configuration that it doesn't recognize in the [`karpenter-global-settings`]({{<ref "./concepts/settings#configmap" >}}) ConfigMap, so leaving the `aws.nodeNameConvention` in the ConfigMap will simply cause this setting to be ignored.
 * Karpenter now defines a set of "restricted tags" which can't be overridden with custom tagging in the AWSNodeTemplate or in the [`karpenter-global-settings`]({{<ref "./concepts/settings#configmap" >}}) ConfigMap. If you are currently using any of these tag overrides when tagging your instances, webhook validation will now fail. These tags include:

website/content/en/v0.28/upgrade-guide.md

@@ -103,6 +103,11 @@ Snapshot releases are tagged with the git commit hash prefixed by the Karpenter
 ## Released Upgrade Notes
 
 ### Upgrading to v0.28.0+
+
+{{% alert title="Warning" color="warning" %}}
+Karpenter v0.28.0 is incompatible with Kubernetes version 1.26+, which can result in additional node scale outs when using `--cloudprovider=external`, which is the default for the EKS Optimized AMI. See: https://github.com/aws/karpenter-core/pull/375
+{{% /alert %}}
+
 * The `extraObjects` value is now removed from the Helm chart. Having this value in the chart proved to not work in the majority of Karpenter installs and often led to anti-patterns, where the Karpenter resources installed to manage Karpenter's capacity were directly tied to the install of the Karpenter controller deployments. The Karpenter team recommends that, if you want to install Karpenter manifests alongside the Karpenter helm chart, to do so by creating a separate chart for the manifests, creating a dependency on the controller chart.
 * The `aws.nodeNameConvention` setting is now removed from the [`karpenter-global-settings`]({{<ref "./concepts/settings#configmap" >}}) ConfigMap. Because Karpenter is now driving its orchestration of capacity through Machines, it no longer needs to know the node name, making this setting obsolete. Karpenter ignores configuration that it doesn't recognize in the [`karpenter-global-settings`]({{<ref "./concepts/settings#configmap" >}}) ConfigMap, so leaving the `aws.nodeNameConvention` in the ConfigMap will simply cause this setting to be ignored.
 * Karpenter now defines a set of "restricted tags" which can't be overridden with custom tagging in the AWSNodeTemplate or in the [`karpenter-global-settings`]({{<ref "./concepts/settings#configmap" >}}) ConfigMap. If you are currently using any of these tag overrides when tagging your instances, webhook validation will now fail. These tags include: