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conf: Add VM Generation ID parse/format support

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The VM Generation ID is a mechanism to provide a unique 128-bit,
cryptographically random, and integer value identifier known as
the GUID (Globally Unique Identifier) to the guest OS. The value
is used to help notify the guest operating system when the virtual
machine is executed with a different configuration.

This patch adds support for a new "genid" XML element similar to
the "uuid" element. The "genid" element can have two forms "<genid/>"
or "<genid>$GUID</genid>". If the $GUID is not provided, libvirt
will generate one and save it in the XML.

Since adding support for a generated GUID (or UUID like) value to
be displayed modifying the xml2xml test to include virrandommock.so
is necessary since it will generate a "known" value.

Signed-off-by: John Ferlan <jferlan@redhat.com>
ACKed-by: Michal Privoznik <mprivozn@redhat.com>
This commit is contained in:
John Ferlan
2018-04-09 12:10:02 -04:00
parent c7151b0e4d
commit b50efe97ad
11 changed files with 290 additions and 1 deletions
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27
docs/formatdomain.html.in
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@@ -34,6 +34,7 @@
&lt;domain type='kvm' id='1'&gt;
&lt;name&gt;MyGuest&lt;/name&gt;
&lt;uuid&gt;4dea22b3-1d52-d8f3-2516-782e98ab3fa0&lt;/uuid&gt;
&lt;genid&gt;43dc0cf8-809b-4adb-9bea-a9abb5f3d90e&lt;/genid&gt;
&lt;title&gt;A short description - title - of the domain&lt;/title&gt;
&lt;description&gt;Some human readable description&lt;/description&gt;
&lt;metadata&gt;
@@ -61,6 +62,32 @@
specification. <span class="since">Since 0.0.1, sysinfo
since 0.8.7</span></dd>
<dt><code>genid</code></dt>
<dd><span class="since">Since 4.4.0</span>, the <code>genid</code>
element can be used to add a Virtual Machine Generation ID which
exposes a 128-bit, cryptographically random, integer value identifier,
referred to as a Globally Unique Identifier (GUID) using the same
format as the <code>uuid</code>. The value is used to help notify
the guest operating system when the virtual machine is re-executing
something that has already executed before, such as:
<ul>
<li>VM starts executing a snapshot</li>
<li>VM is recovered from backup</li>
<li>VM is failover in a disaster recovery environment</li>
<li>VM is imported, copied, or cloned</li>
</ul>
The guest operating system notices the change and is then able to
react as appropriate by marking its copies of distributed databases
as dirty, re-initializing its random number generator, etc.
<p>
The libvirt XML parser will accept both a provided GUID value
or just &lt;genid/&gt; in which case a GUID will be generated
and saved in the XML. For the transitions such as above, libvirt
will change the GUID before re-executing.</p></dd>
<dt><code>title</code></dt>
<dd>The optional element <code>title</code> provides space for a
short description of the domain. The title should not contain