Onboarding SSH connected Ubuntu client with install-created user (#3542)

ttps://bugzilla.suse.com/show_bug.cgi?id=1213437
SUSE/spacewalk#22053

CHANGELOG.md

@@ -1,3 +1,5 @@
+- Documented onboarding SSH connected Ubuntu clients with install-created
+  user in Client Configuration Guide (bsc#1213437)
 - Added Saline documentation to Salt Guide
 - Replaced mgradm with mrgctl in Installation and Upgrade Guide
 - Corrected metadata signing section in Administration Guide

modules/client-configuration/pages/clients-ubuntu.adoc

@@ -232,6 +232,10 @@ If the default user has been granted administrative privileges during installati
 With cloud instances this does not happen because [command]``cloud-init`` automatically creates a file under [path]``/etc/sudoers.d`` and grants privilege escalation through [command]``sudo`` without the need for a password.
 ====
 
+
+
+=== Grant Root User Access
+
 .Procedure: Granting Root User Access
 
 . On the client, edit the [filename]``sudoers`` file:
@@ -256,6 +260,36 @@ We recommend that you remove the line from the [path]``sudoers`` file after the
 
 
 
+=== Bootstrap as Install-created User via SSH
+
+To bootstrap an Ubuntu client via SSH you must add the install-created user to the sudo group.
+Then run the bootstrap script from the client.
+
+.Procedure: Adding Install-created User to sudo Group and Bootstrapping via SSH
+
+. On the client, as root, run from the command line (replace [literal]``<username>`` with the name of the install-created user):
++
+
+----
+sudo usermod -aG sudo <username>
+----
+
+. Bootstrap the client system from its command line (replace [literal]``<SERVER_FQDN>`` with the fully qualified domain name of the {productname} Server):
++
+
+----
+sudo su -
+curl -Sks https://<SERVER_FQDN>/pub/bootstrap/bootstrap-script.sh | /bin/bash
+----
+
+[IMPORTANT]
+====
+{ubuntu} can only be bootstrapped using the corresponding {ubuntu} bootstrap script run from the client system's command line after issuing [command]``sudo su -`` as above.
+It cannot be bootstrapped via the {productname} {webui} due to the fact that the root user is disabled on {ubuntu} by default, and that the {webui} does not permit for privilege escalation of the {ubuntu} install-created user.
+====
+
+
+
 == Register Clients
 
 include::snippets/create_bootstrap_repo_register.adoc[]