Added content for Guest OS customization for cloud-init

Change-Id: I6026ec3a7ce707b18a23dacdc6b9aa0c962d89a1 Reviewed-on: http://photon-jenkins.eng.vmware.com:8082/8368 Reviewed-by: Keerthana K <[email protected]> Reviewed-by: Anish Swaminathan <[email protected]> Tested-by: Anish Swaminathan <[email protected]>
agentdavidjoseph · Nov 5, 2019 · 35e1a5b · 35e1a5b
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diff --git a/docs/SUMMARY.md b/docs/SUMMARY.md
@@ -113,6 +113,7 @@
     - [Cloud-Init on Photon OS](photon_admin/cloud-init-on-photon-os.md)
         - [Cloud-Init Overview](photon_admin/cloud-init.md)
         - [Deploy Photon OS With cloud-init](photon_admin/deploy_photon_with_cloud-init.md) 
+        - [Customizing Guest OS using Cloud-Init](photon_admin/Customizing_Gos_Cloudinit.md)
         - [Creating a Stand-Alone Photon Machine with cloud-init](photon_admin/creating-a-stand-alone-photon-machine-with-cloud-init.md)
         -   [Customizing a Photon OS Machine on EC2](photon_admin/customizing-a-photon-os-machine-on-ec2.md)
         -   [Running a Photon OS Machine on GCE](photon_admin/running-a-photon-os-machine-on-gce.md)

diff --git a/docs/photon_admin/Customizing_Gos_Cloudinit.md b/docs/photon_admin/Customizing_Gos_Cloudinit.md
@@ -0,0 +1,31 @@
+# Customizing Guest OS using Cloud-Init
+
+A guest operating system is an operating system that runs inside a virtual machine. You can install a guest operating system in a virtual machine and control guest operating system customization for virtual machines created from vApp templates.
+
+When you customize your guest OS you can set up a virtual machine with the operating system that you want.
+
+### Procedure
+1. Perform the following steps before cloning or customizing the guest operating system:    
+  1. Ensure that `disable_vmware_customization` is set to false in the `/etc/cloud/cloud.cfg` file.
+  1. Set `manage_etc_hosts: true` in the `/etc/cloud/cloud.cfg` file.
+  1. Make a backup of the `99-disable-networking-config.cfg` file and delete the file from `/etc/cloud/cloud.cfg.d` folder after backup.
+1. Clone the VM or customize the guest operating system.
+1. After you clone your VM or customize the guest operating system, perform the following steps:
+  1. Ensure that `disable_vmware_customization` is set to true in the `/etc/cloud/cloud.cfg` file in the newly created VM and the VM from where cloning was initiated.
+  1. Remove `manage_etc_hosts: true` from the `/etc/cloud/cloud.cfg` file in the newly created VM and the VM from where cloning was initiated.
+  1. Add a copy of the backed up file `99-disable-networking-config.cfg` to its original folder `/etc/cloud/cloud.cfg.d` in the newly created VM and the VM from where cloning was initiated.
+
+**Note**:
+
+1. The `disable_vmware_customization` flag in `/etc/cloud/cloud.cfg.d` file decides which customization workflow to be initiated.
+  - Setting this to **false** invokes the Cloud-Init GOS customization workflow.
+  - Setting this to **true** invokes the traditional GOSC script based customization workflow. 
+1. When the `manage_etc_hosts` flag is set to **true**, Cloud-Init can edit the `/etc/hosts` file with the updated values.
+
+    When the flag is set to **true** Cloud-Init edits the `/etc/hosts` file, even when there is no cloud config metadata available. Remove this entry once the Cloud-Init GOS customization is done, to stop Cloud-Init from editing `/etc/hosts` file and set a fallback configuration.
+1. The `99-disable-networking-config.cfg` file is packaged as part of Cloud-Init RPM in photon and it prevents Cloud-Init from configuring the network. Delete this file before starting the Cloud-Init customization and then paste the backup of the file in the `/etc/cloud/cloud.cfg.d/` folder once the cloud-init workflow is complete. It is important to replace this file after Cloud-Init customization to avoid removal of network configuration in the Cloud-Init instance.
+
+
+### Result
+
+Cloud-Init guest OS customization is now enabled.
diff --git a/docs/photon_admin/SUMMARY.md b/docs/photon_admin/SUMMARY.md
@@ -53,6 +53,7 @@
 - [Cloud-Init on Photon OS](cloud-init-on-photon-os.md)
     - [Cloud-Init Overview](cloud-init.md)
     - [Deploy Photon OS With cloud-init](deploy_photon_with_cloud-init.md)
+    - [Customizing Guest OS using Cloud-Init](Customizing_Gos_Cloudinit.md)
     - [Creating a Stand-Alone Photon Machine with cloud-init](creating-a-stand-alone-photon-machine-with-cloud-init.md)
     -   [Customizing a Photon OS Machine on EC2](customizing-a-photon-os-machine-on-ec2.md)
     -   [Running a Photon OS Machine on GCE](running-a-photon-os-machine-on-gce.md)

diff --git a/docs/photon_admin/cloud-init-on-photon-os.md b/docs/photon_admin/cloud-init-on-photon-os.md
@@ -4,6 +4,7 @@ The minimal and full versions of Photon OS include the cloud-init service as a b
 
 - [Cloud-Init Overview](cloud-init.md)
 - [Deploy Photon OS With cloud-init](deploy_photon_with_cloud-init.md)
+- [Customizing Guest OS for Cloud-Init](Customizing_Gos_Cloudinit.md)
 - [Creating a Stand-Alone Photon Machine with cloud-init](creating-a-stand-alone-photon-machine-with-cloud-init.md)
 - [Customizing a Photon OS Machine on EC2](customizing-a-photon-os-machine-on-ec2.md)
 - [Running a Photon OS Machine on GCE](running-a-photon-os-machine-on-gce.md)