Merge pull request #45271 from JStickler/OSSMDOC-442

OSSMDOC-442 Clarify lack of support for EnvoyFilters.

Author: JStickler

modules/ossm-rn-deprecated-features.adoc

@@ -21,8 +21,6 @@ In Service Mesh 2.1, the Mixer component is removed. Bug fixes and support is pr
 
 Upgrading from a Service Mesh 2.0.x release to 2.1 will not proceed if Mixer plug-ins are enabled. Mixer plug-ins must be ported to WebAssembly Extensions.
 
-With Mixer removed, custom metrics for telemetry must be obtained using Envoy filter.
-
 == Deprecated features {SMProductName} 2.0
 
 The Mixer component was deprecated in release 2.0 and will be removed in release 2.1. While using Mixer for implementing extensions was still supported in release 2.0, extensions should have been migrated to the new link:https://istio.io/latest/blog/2020/wasm-announce/[WebAssembly] mechanism.

modules/ossm-supported-configurations.adoc

@@ -35,6 +35,11 @@ For additional information about {SMProductName} lifecycle and supported configu
 * OVN-Kubernetes is supported on {product-title} 4.7.32+, {product-title} 4.8.12+, and {product-title} 4.9+.
 * Third-Party Container Network Interface (CNI) plug-ins that have been certified on {product-title} and passed {SMProductShortName} conformance testing. See link:https://access.redhat.com/articles/5436171[Certified OpenShift CNI Plug-ins] for more information.
 
+[id="ossm-supported-configurations-sm_{context}"]
+== Supported configurations for Service Mesh
+
+* {SMProductName} does not support `EnvoyFilter` configuration except where explicitly documented.
+
 [id="ossm-supported-configurations-kiali_{context}"]
 == Supported configurations for Kiali
 

modules/ossm-vs-istio.adoc

@@ -100,6 +100,11 @@ spec:
 * Godebug has been removed from all templates
 * The `istio-multi` ServiceAccount and ClusterRoleBinding have been removed, as well as the `istio-reader` ClusterRole.
 
+[id="ossm-envoy-filters_{context}"]
+== Envoy filters
+
+{SMProductName} does not support `EnvoyFilter` configuration except where explicitly documented. Due to tight coupling with the underlying Envoy APIs, backward compatibility cannot be maintained. `EnvoyFilter` patches are very sensitive to the format of the Envoy configuration that is generated by Istio. If the configuration generated by Istio changes, it has the potential to break the application of the `EnvoyFilter`.
+
 [id="ossm-envoy-services_{context}"]
 == Envoy services