kvm: direct download templates for system VM (apache#134)

* kvm: direct download templates for system VM

System VMs now support direct download templates.
Different direct download timeouts have been made configurable with new global settings.

Signed-off-by: Abhishek Kumar <abhishek.mrt22@gmail.com>

* suggestion applied

Co-authored-by: Andrija Panic <45762285+andrijapanicsb@users.noreply.github.com>

Co-authored-by: Andrija Panic <45762285+andrijapanicsb@users.noreply.github.com>

Author: shwstppr

source/adminguide/templates/_bypass-secondary-storage-kvm.rst

@@ -17,7 +17,7 @@
 .. _bypass-secondary-storage-kvm:
 
 Bypassing Secondary Storage For KVM templates
---------------------------------------------
+---------------------------------------------
 
 CloudStack provides an additional way to register and use templates on KVM.
 
@@ -41,6 +41,13 @@ To enable this option for a template:
 
 After the template is registered, it is automatically available for VM deployments.
 
+From CloudStack 4.14.0, system VM templates also support direct download. An administrator can register a new system VM template as ROUTING or USER type with the direct download flag, and it can be changed to SYSTEM type during the upgrade or by out-of-band database changes. Type of newly registered template can be changed to SYSTEM in the database using a SQL query similar to:
+
+.. code:: bash
+
+      UPDATE cloud.vm_template SET type=’SYSTEM’ WHERE uuid=’UUID_OF_NEW_TEMPLATE’;
+
+
 Uploading Certificates for Direct Downloads
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 For direct downloads over HTTPS, the KVM hosts must have valid certificates. These certificates can be either self-signed or signed and will allow the KVM hosts to access the templates/ISOs and download them.
@@ -78,7 +85,7 @@ CloudStack provides some APIs to handle certificates for direct downloads:
          upload templatedirectdownloadcertificate hypervisor=KVM name=CERTIFICATE_ALIAS zoneid=ZONE_ID certificate=CERTIFICATE_FORMATTED hostid=HOST_ID
 
 Syncronising Certificates for Direct Downloads
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 As new hosts may be added to a zone which do not include a certificate which was previously uploaded to pre-existing hosts.
 
@@ -88,3 +95,14 @@ CloudStack provides a way to synchronize certificates across all the connected h
 - Enumerate the connected hosts in a zone
 - Check which hosts are missing the certificates which have been already uploaded to other hosts
 - Upload missing certificates to hosts
+
+Direct Download Timeouts
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+With 4.14.0, ability to configure different timeout values for the direct downloading of templates has been added. Three new global settings have been added for this:
+
+- **direct.download.connect.timeout** - Connection establishment timeout in milliseconds for direct download. Default value: 5000 milliseconds.
+
+- **direct.download.socket.timeout** - Socket timeout (SO_TIMEOUT) in milliseconds for direct download. Default value: 5000 milliseconds.
+
+- **direct.download.connection.request.timeout** - Requesting a connection from connection manager timeout in milliseconds for direct download. Default value: 5000 milliseconds. This setting is hidden and not visible in UI.