OSDOCS#14017: HostedCluster and NodePool version compatibility

Author: xenolinux

hosted_control_planes/hcp-updating.adoc

@@ -19,6 +19,9 @@ include::modules/hcp-updating-requirements.adoc[leveloffset=+1]
 * xref:../hosted_control_planes/hcp-updating.adoc#hcp-update-ocp-hc_hcp-updating[Updating a control plane in a hosted cluster]
 * xref:../hosted_control_planes/hcp-updating.adoc#hcp-update-node-pools_hcp-updating[Updating node pools in a hosted cluster]
 
+// HostedCluster and NodePool version compatibility check (SupportedVersionSkew)
+include::modules/hcp-np-version-skew.adoc[leveloffset=+1]
+
 include::modules/hcp-get-ocp-channel.adoc[leveloffset=+1]
 
 include::modules/hcp-get-upgrade-versions.adoc[leveloffset=+1]

modules/hcp-np-version-skew.adoc

@@ -0,0 +1,40 @@
+// Module included in the following assemblies
+//
+// * hosted_control_planes/hcp-updating.adoc
+
+:_mod-docs-content-type: REFERENCE
+[id="hcp-np-version-skew_{context}"]
+= About HostedCluster and NodePool version compatibility
+
+In {hcp}, ensure to check that your `NodePool` version is compatible with your `HostedCluster` version by reviewing the following rules:
+
+* The `NodePool` version cannot be higher than the `HostedCluster` version.
+** For `4.<x>` versions, where `<x>` is an _even_ release number, such as 4.18, you must use up to 2 minor versions, for example, 4.17 and 4.16.
+** For `4.<x>` versions, where `<x>` is an _odd_ release number, such as 4.17, you must use up to 1 minor version, for example, 4.16.
+
+* The `NodePool` controller sets the `SupportedVersionSkew` condition by default to report one of the following version compatibility statuses:
+** `True`: Indicates that the `NodePool` version is compatible with the HostedCluster version.
+** `False`: Indicates that the `NodePool` version is incompatible with detailed error messages. If you see the version incompatibility issues, you must upgrade or downgrade `NodePool` to a compatible version.
+
+
+.Example table of the supported node pool versions for your hosted cluster
+[cols="1,1,1",options="header"]
+|===
+|Hosted cluster version |Supported node pool versions |Unsupported node pool versions
+
+|4.18
+|4.17, 4.16
+|4.15, 4.14
+
+|4.17
+|4.16
+|4.15
+
+|4.18.5
+|4.18.5, 4.18.4, 4.17.z, 4.16.z
+|4.15.z and below, 4.19.z and above
+
+|4.17.5
+|4.17.5, 4.17.4, 4.16.z
+|4.15.z and below, 4.18.z and above
+|===