OSDOCS-16614: Documented VIP optional with user-managed LB feature

Author: dfitzmau

installing/installing_bare_metal/upi/installing-bare-metal-network-customizations.adoc

@@ -69,6 +69,8 @@ include::modules/installation-dns-user-infra.adoc[leveloffset=+2]
 
 * xref:../../../installing/installing_bare_metal/upi/installing-bare-metal-network-customizations.adoc#installation-user-provisioned-validating-dns_installing-bare-metal-network-customizations[Validating DNS resolution for user-provisioned infrastructure]
 
+include::modules/installation-bare-metal-dns-record-type.adoc[leveloffset=+2]
+
 include::modules/installation-load-balancing-user-infra.adoc[leveloffset=+2]
 
 // Creating a manifest object that includes a customized `br-ex` bridge

installing/installing_bare_metal/upi/installing-bare-metal.adoc

@@ -77,6 +77,8 @@ include::modules/installation-dns-user-infra.adoc[leveloffset=+2]
 
 * xref:../../../installing/installing_bare_metal/upi/installing-bare-metal.adoc#installation-user-provisioned-validating-dns_installing-bare-metal[Validating DNS resolution for user-provisioned infrastructure]
 
+include::modules/installation-bare-metal-dns-record-type.adoc[leveloffset=+2]
+
 // Load balancing requirements for user-provisioned infrastructure
 include::modules/installation-load-balancing-user-infra.adoc[leveloffset=+2]
 

installing/installing_bare_metal/upi/installing-restricted-networks-bare-metal.adoc

@@ -84,6 +84,8 @@ include::modules/installation-dns-user-infra.adoc[leveloffset=+2]
 
 * xref:../../../installing/installing_bare_metal/upi/installing-restricted-networks-bare-metal.adoc#installation-user-provisioned-validating-dns_installing-restricted-networks-bare-metal[Validating DNS resolution for user-provisioned infrastructure]
 
+include::modules/installation-bare-metal-dns-record-type.adoc[leveloffset=+2]
+
 include::modules/installation-load-balancing-user-infra.adoc[leveloffset=+2]
 
 // Creating a manifest object that includes a customized `br-ex` bridge

modules/installation-bare-metal-dns-record-type.adoc

@@ -0,0 +1,62 @@
+// Module included in the following assemblies:
+//
+// * installing/installing_bare_metal/upi/installing-bare-metal-network-customizations.adoc
+// * installing/installing_bare_metal/upi/installing-bare-metal.adoc
+// * installing/installing_bare_metal/upi/installing-restricted-networks-bare-metal.adoc
+
+:_mod-docs-content-type: CONCEPT
+[id="installation-bare-metal-dns-record-type_{context}"]
+= Configuring the DnsRecordsType parameter
+
+[role="_abstract"]
+You can use the `DnsRecordsType` parameter in your `infrastructure.config.openshift.io` custom resource (CR) to set if the internal DNS service or an external source provides the necessary records for `api`, `api-int`, and `ingress` DNS records.
+
+:FeatureName: Configuring the DnsRecordsType parameter
+include::snippets/technology-preview.adoc[]
+
+To use the parameter, you must enable the `OnPremDNSRecords` feature gate in the `config.yaml` file.
+
+The `dnsRecordsType` parameter supports the following values:
+
+* `Internal`: The default value. Setting this value causes the cluster infrastructure to automatically create and maintain the necessary DNS records.
+* `External`: You can use this value only if you set the `loadBalancer.type` parameter to `UserManaged`. The cluster does not manage the DNS records. You must manually configure DNS records on an external DNS server.
+
+.Prerequisites
+
+* You created DNS records, such as `api`, `api-int`, or `\*.apps`.
+* You configured a user-managed load balancer for your cluster. 
+* If you intend on setting `dnsRecordsType.External` in the `infrastructure.config.openshift.io` CR , you must initially configure cluster nodes to use the specific external server for DNS resolution.
+
+.Procedure
+
+. Edit the `featuregate.config.openshift.io/cluster` CR and set the `featureSet.customNoUpgrade.enabled` parameter to the `OnPremDNSRecords` value:
++
+[source,yaml]
+----
+apiVersion: config.openshift.io/v1
+kind: FeatureGate
+metadata:
+  name: cluster
+spec:
+  featureSet: CustomNoUpgrade
+  customNoUpgrade:
+    enabled:
+      - OnPremDNSRecords
+# ...
+----
+
+* Edit your `infrastructure.config.openshift.io` CR by setting the `dnsRecordsType` parameter to the `External` value:
++
+[source,yaml]
+----
+apiVersion: config.openshift.io/v1
+kind: Infrastructure
+metadata:
+  name: cluster
+spec:
+  platformSpec:
+    baremetal:
+      dnsRecordsType: External
+# ...
+----
+

modules/nw-dns-forward.adoc

@@ -20,9 +20,11 @@ endif::openshift-rosa,openshift-rosa-hcp,openshift-dedicated[]
 * Provide a list of upstream DNS servers (`spec.upstreamResolvers`).
 * Change the default forwarding policy.
 
-[NOTE]
-====
 A DNS forwarding configuration for the default domain can have both the default servers specified in the `/etc/resolv.conf` file and the upstream DNS servers.
+
+[IMPORTANT]
+====
+During pod creation, Kubernetes uses the `/etc/resolv.conf` file that exists on a node. If you modify the `/etc/resolv.conf` file on a host node, the changes do not propagate to the `/etc/resolv.conf` file that exists in a container. You must recreate the container for changes to take effect.
 ====
 
 .Procedure

modules/virt-example-nmstate-IP-management.adoc

@@ -139,6 +139,11 @@ The following example shows a default situation that stores DNS values globally:
 
 * Configure a static DNS without a network interface. Note that when updating the `/etc/resolv.conf` file on a host node, you do not need to specify an interface, IPv4 or IPv6, in the `NodeNetworkConfigurationPolicy` (NNCP) manifest.
 +
+[IMPORTANT]
+====
+During pod creation, Kubernetes uses the `/etc/resolv.conf` file that exists on a node. If you modify the `/etc/resolv.conf` file on a host node, the changes do not propagate to the `/etc/resolv.conf` file that exists in a container. You must recreate the container for changes to take effect.
+====
++
 Example of a DNS configuration for a network interface that globally stores DNS values:
 +
 [source,yaml]