Add details on host groups (#2685)

* Define host group settings persistance
* Edit host group settings hierarchy and priorities
* Split host group settings into a separate module
* Split host group-related modules into a separate assembly

---------

Co-authored-by: Jeremy Lenz <jlenz@redhat.com>
Co-authored-by: Shimon Shtein <sshtein@redhat.com>

guides/common/assembly_administering-hosts.adoc

@@ -16,14 +16,6 @@ include::modules/proc_changing-the-module-stream-for-a-host.adoc[leveloffset=+1]
 
 include::modules/proc_enabling-custom-repositories-on-content-hosts.adoc[leveloffset=+1]
 
-include::modules/proc_creating-a-host-group.adoc[leveloffset=+1]
-
-include::modules/proc_creating-a-host-group-for-each-lifecycle-environment.adoc[leveloffset=+1]
-
-include::modules/proc_adding-a-host-to-a-host-group.adoc[leveloffset=+1]
-
-include::modules/proc_changing-the-host-group-of-a-host.adoc[leveloffset=+1]
-
 ifdef::katello,satellite,orcharhino[]
 include::modules/proc_adding-a-host-to-a-host-collection.adoc[leveloffset=+1]
 

guides/common/assembly_working-with-host-groups.adoc

@@ -0,0 +1,11 @@
+include::modules/con_working-with-host-groups.adoc[]
+
+include::modules/con_host-group-settings-and-nested-host-groups.adoc[leveloffset=+1]
+
+include::modules/proc_creating-a-host-group.adoc[leveloffset=+1]
+
+include::modules/proc_creating-a-host-group-for-each-lifecycle-environment.adoc[leveloffset=+1]
+
+include::modules/proc_adding-a-host-to-a-host-group.adoc[leveloffset=+1]
+
+include::modules/proc_changing-the-host-group-of-a-host.adoc[leveloffset=+1]

guides/common/modules/con_host-group-settings-and-nested-host-groups.adoc

@@ -0,0 +1,133 @@
+[id="Host_Group_Settings_and_Nested_Host_Groups_{context}"]
+= Host Group Settings and Nested Host Groups
+
+A host group can define many settings for hosts, such as Lifecycle Environment, Content View, or Ansible roles that are available to the hosts.
+
+IMPORTANT: When you change the settings of an existing host group, the new settings do not propagate to the hosts assigned to the host group.
+Only Puppet class settings get updated on hosts after you change them in the host group.
+
+You can create a hierarchy of host groups.
+Aim to have one base level host group that represents all hosts in your organization and provides general settings, and then nested groups that provide specific settings.
+
+{Project} applies host settings in the following order when nesting host groups:
+
+* Host settings take priority over host group settings.
+* Nested host group settings take priority over parent host group settings.
+
+.Nested Host Group Hierarchy
+====
+You create a top-level host group named *Base* and two nested host groups named *Webserver* and *Storage*.
+The nested host groups are associated with multiple hosts.
+You also create host `custom.example.com` that is not associated with any host group.
+
+You define the operating system on the top-level host group (*Base*) and Ansible roles on the nested host groups (*Webservers* and *Storage*).
+
+[cols="1,1,1,2"]
+|===
+|Top-level host group |Nested host group |Hosts |Settings inherited from host groups
+
+.4+|*Base*
+
+This host group applies the `{EL}{nbsp}8.8` operating system setting.
+
+// Rows related to Webservers
+.2+|*Webservers*
+
+This host group applies the `linux-system-roles.selinux` Ansible role.
+
+|*webserver1.example.com*
+
+.2+a|Hosts use the following settings:
+
+* `{EL}{nbsp}8.8` defined by host group *Base*
+* `linux-system-roles.selinux` defined by host group *Webservers*
+
+|*webserver2.example.com*
+
+// Rows related to Storage
+.2+|*Storage*
+
+This host group applies the `linux-system-roles.postfix` Ansible role.
+
+|*storage1.example.com*
+
+.2+a|Hosts use the following settings:
+
+* `{EL}{nbsp}8.8` defined by host group *Base*
+* `linux-system-roles.postfix` defined by host group *Storage*
+
+|*storage2.example.com*
+
+// Row related to No host group
+2+|[No host group]
+
+|*custom.example.com*
+
+|No settings inherited from host groups.
+
+|===
+====
+
+.Nested Host Group Settings
+====
+You create a top-level host group named *Base* and two nested host groups named *Webserver* and *Storage*.
+You also create host `custom.example.com` that is associated with the top-level host group *Base*, but no nested host group.
+
+You define different values for the operating system and Ansible role settings on the top-level host group (*Base*) and nested host groups (*Webserver* and *Storage*).
+
+[cols="1,1,1,2"]
+|===
+|Top-level host group |Nested host group |Host |Settings inherited from host groups
+
+.5+a|*Base*
+
+This host group applies these settings:
+
+* The `{EL}{nbsp}8.8` operating system
+* The `linux-system-roles.selinux` Ansible role
+
+// Rows related to Webservers
+.2+a|*Webservers*
+
+This host group applies these settings:
+
+* The `{EL}{nbsp}8.9` operating system
+* No Ansible role
+
+|*webserver1.example.com*
+
+.2+a|Hosts use the following settings:
+
+* The `{EL}{nbsp}8.9` operating system from host group *Webservers*
+* The `linux-system-roles.selinux` Ansible role from host group *Base*
+
+|*webserver2.example.com*
+
+// Rows related to Storage
+.2+a|*Storage*
+
+This host group applies these settings:
+
+* No operating system
+* The `linux-system-roles.postfix` Ansible role
+
+|*storage1.example.com*
+
+.2+a|Hosts use the following settings:
+
+* The `{EL}{nbsp}8.8` operating system from host group *Base*
+* The `linux-system-roles.postfix` Ansible role from host group *Storage*
+
+|*storage2.example.com*
+
+// Row related to custom.example.com
+|[No nested host group]
+|*custom.example.com*
+a|Host uses the following settings:
+
+* The `{EL}{nbsp}8.8` operating system from host group *Base*
+* The `linux-system-roles.selinux` Ansible role from host group *Base*
+
+|===
+====
+

guides/common/modules/con_working-with-host-groups.adoc

@@ -0,0 +1,6 @@
+[id="Working_with_Host_Groups_{context}"]
+= Working with Host Groups
+
+A host group acts as a template for common host settings.
+Instead of defining the settings individually for each host, use host groups to define common settings once and apply them to multiple hosts.
+

guides/common/modules/proc_creating-a-host-group.adoc

@@ -1,35 +1,10 @@
 [id="Creating_a_Host_Group_{context}"]
 = Creating a Host Group
 
-If you create a high volume of hosts, many of the hosts can have common settings and attributes.
-Adding these settings and attributes for every new host is time consuming.
-If you use host groups, you can apply common attributes to hosts that you create.
-
-A host group functions as a template for common host settings, containing many of the same details that you provide to hosts.
-When you create a host with a host group, the host inherits the defined settings from the host group.
-You can then provide additional details to individualize the host.
+Create a host group to be able to apply host settings to multiple hosts.
 
 To use the CLI instead of the {ProjectWebUI}, see the xref:cli-creating-a-host-group_{context}[].
 
-.Host Group Hierarchy
-You can create a hierarchy of host groups.
-Aim to have one base level host group that represents all hosts in your organization and provide general settings, and then nested groups to provide specific settings.
-For example, you can have a base level host group that defines the operating system, and two nested host groups that inherit the base level host group:
-
-* *Hostgroup:* `Base` ({EL} 8.8)
-** *Hostgroup:* `Webserver` (applies the `nginx` Puppet class)
-*** *Host:* `webserver1.example.com` (web server)
-*** *Host:* `webserver2.example.com` (web server)
-** *Hostgroup:* `Storage` (applies the `nfs` Puppet class)
-*** *Host:* `storage1.example.com` (storage server)
-*** *Host:* `storage2.example.com` (storage server)
-** *Host:* `custom.example.com` (custom host)
-
-In this example, all hosts use {RHEL} 7.6 as their operating system because of their inheritance of the `Base` host group.
-The two web server hosts inherit the settings from the `Webserver` host group, which includes the `nginx` Puppet class and the settings from the `Base` host group.
-The two storage servers inherit the settings from the `Storage` host group, which includes the `nfs` Puppet class and the settings from the `Base` host group.
-The custom host only inherits the settings from the `Base` host group.
-
 .Procedure
 . In the {ProjectWebUI}, navigate to *Configure* > *Host Groups* and click *Create Host Group*.
 . If you have an existing host group that you want to inherit attributes from, you can select a host group from the *Parent* list.

guides/doc-Managing_Hosts/master.adoc

@@ -19,6 +19,8 @@ include::common/modules/con_overview-of-hosts.adoc[leveloffset=+1]
 
 include::common/assembly_administering-hosts.adoc[leveloffset=+1]
 
+include::common/assembly_working-with-host-groups.adoc[leveloffset=+1]
+
 include::common/assembly_registering-hosts.adoc[leveloffset=+1]
 
 include::common/assembly_managing-network-interfaces.adoc[leveloffset=+1]