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Libvirt is an open source toolkit which can interact with KVM, Xen, and several other virtualization architectures.
libvirt.pm
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- libvirt.pm is the main provisioning module
- Computers should have their provisioningID attributes set to point to this module in order to utilize it
- Implements the required provisioning module subroutines: load, capture, node_status, power_status, power_on, power_off, power_reset...
- Implements the functions provided by libvirt: define, start, destroy...
- Does not contain code specific to any of the libvirt driverhypervisors supported by libvirt (KVM, Xen, etc)
- File location: lib/VCL/Module/Provisioning/Libvirt.pm
- Automatically determines which hypervisor driver object to use upon initialization by examining the host
...
- Hypervisor driver directory: lib/VCL/Module/Provisioning/libvirt/
- Example: lib/VCL/Module/Provisioning/libvirt/KVM.pm
- Contains code which only applies to KVM
- Calls qemu-img to perform image file operations
Virtual Machine Disks
A master disk image is stored in the location specified by the datastore path in the VM host profile. A copy on write virtual disk image is created for each virtual machine when it is loaded. The master disk image is used as a read-only backing file for the copy on write disk images. Each VM writes to its own copy on write disk image. Using copy on write virtual disks allows VMs to be loaded without having to create a complete copy of the master disk image.
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libvirt.pm
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<title>VCL::Provisioning::libvirt - VCL provisioning module to support the libvirt toolkit</title>
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<p><a name="__index__"></a></p>
<!-- INDEX BEGIN -->
<ul>
<li><a href="#name">NAME</a></li>
<li><a href="#synopsis">SYNOPSIS</a></li>
<li><a href="#description">DESCRIPTION</a></li>
<li><a href="#object_methods">OBJECT METHODS</a></li>
<ul>
<li><a href="#initialize">initialize</a></li>
<li><a href="#load">load</a></li>
<li><a href="#capture">capture</a></li>
<li><a href="#node_status">node_status</a></li>
<li><a href="#does_image_exist">does_image_exist</a></li>
<li><a href="#get_image_size">get_image_size</a></li>
<li><a href="#get_image_repository_search_paths">get_image_repository_search_paths</a></li>
<li><a href="#power_status">power_status</a></li>
<li><a href="#power_on">power_on</a></li>
<li><a href="#power_off">power_off</a></li>
<li><a href="#power_reset">power_reset</a></li>
<li><a href="#post_maintenance_action">post_maintenance_action</a></li>
</ul>
<li><a href="#private_methods">PRIVATE METHODS</a></li>
<ul>
<li><a href="#driver">driver</a></li>
<li><a href="#get_driver_name">get_driver_name</a></li>
<li><a href="#get_domain_name">get_domain_name</a></li>
<li><a href="#get_domain_file_base_name">get_domain_file_base_name</a></li>
<li><a href="#get_domain_xml_directory_path">get_domain_xml_directory_path</a></li>
<li><a href="#get_domain_xml_file_path">get_domain_xml_file_path</a></li>
<li><a href="#get_master_image_directory_path">get_master_image_directory_path</a></li>
<li><a href="#get_master_image_file_path">get_master_image_file_path</a></li>
<li><a href="#get_copy_on_write_file_path">get_copy_on_write_file_path</a></li>
<li><a href="#delete_existing_domains">delete_existing_domains</a></li>
<li><a href="#delete_domain">delete_domain</a></li>
<li><a href="#generate_domain_xml">generate_domain_xml</a></li>
<li><a href="#get_domain_info">get_domain_info</a></li>
<li><a href="#get_domain_xml">get_domain_xml</a></li>
<li><a href="#domain_exists">domain_exists</a></li>
<li><a href="#get_snapshot_info">get_snapshot_info</a></li>
<li><a href="#create_snapshot">create_snapshot</a></li>
<li><a href="#delete_snapshot">delete_snapshot</a></li>
<li><a href="#get_image_size_bytes">get_image_size_bytes</a></li>
<li><a href="#find_repository_image_file_paths">find_repository_image_file_paths</a></li>
</ul>
<li><a href="#see_also">SEE ALSO</a></li>
</ul>
<!-- INDEX END -->
<hr />
<p>
</p>
<h1><a name="name">NAME</a></h1>
<p>VCL::Provisioning::libvirt - VCL provisioning module to support the libvirt toolkit</p>
<p>
</p>
<hr />
<h1><a name="synopsis">SYNOPSIS</a></h1>
<pre>
use VCL::Module::Provisioning::libvirt;
my $provisioner = (VCL::Module::Provisioning::libvirt)->new({data_structure => $self->data});</pre>
<p>
</p>
<hr />
<h1><a name="description">DESCRIPTION</a></h1>
<pre>
Provides support allowing VCL to provisioning resources supported by the
libvirt toolkit.
<a href="http://libvirt.org">http://libvirt.org</a></pre>
<p>
</p>
<hr />
<h1><a name="object_methods">OBJECT METHODS</a></h1>
<p>
</p>
<h2><a name="initialize">initialize</a></h2>
<pre>
Parameters : none
Returns : boolean
Description : Enumerates the libvirt driver modules directory:
lib/VCL/Module/Provisioning/libvirt/
Attempts to create and initialize an object for each hypervisor
driver module found in this directory. The first driver module
object successfully initialized is used. This object is made
accessible within this module via $self->driver. This allows
libvirt support driver modules to be added without having to
alter the code in libvirt.pm.</pre>
<p>
</p>
<h2><a name="load">load</a></h2>
<pre>
Parameters : none
Returns : boolean
Description : Loads the requested image on the domain:</pre>
<ul>
<li>
<p>Destroy and delete any domains have already been defined for the computer
assigned to this reservation.</p>
</li>
<li>
<p>Construct the default libvirt XML definition for the domain.</p>
</li>
<li>
<p>Call the libvirt driver module's 'extend_domain_xml' subroutine if it is
implemented. Pass the default domain XML definition hash reference as an
argument. The 'extend_domain_xml' subroutine may add or modify XML values. This
allows the driver module to customize the XML specific to that driver.</p>
</li>
<li>
<p>Call the driver module's 'pre_define' subroutine if it is implemented. This
subroutine completes any necessary tasks which are specific to the driver being
used prior to defining the domain.</p>
</li>
<li>
<p>Create a text file on the node containing the domain XML definition.</p>
</li>
<li>
<p>Define the domain on the node by calling 'virsh define <XML file>'.</p>
</li>
<li>
<p>Power on the domain.</p>
</li>
<li>
<p>Call the domain guest OS module's 'post_load' subroutine if implemented.</p>
</li>
</ul>
<p>
</p>
<h2><a name="capture">capture</a></h2>
<pre>
Parameters : none
Returns : boolean
Description : Captures the image currently loaded on the computer.</pre>
<p>
</p>
<h2><a name="node_status">node_status</a></h2>
<pre>
Parameters : $computer_id (optional)
Returns : string
Description : Checks the status of the computer in order to determine if the
computer is ready to be reserved or needs to be reloaded. A
string is returned depending on the status of the computer:
'READY':
* Computer is ready to be reserved
* It is accessible
* It is loaded with the correct image
* OS module's post-load tasks have run
'POST_LOAD':
* Computer is loaded with the correct image
* OS module's post-load tasks have not run
'RELOAD':
* Computer is not accessible or not loaded with the correct
image</pre>
<p>
</p>
<h2><a name="does_image_exist">does_image_exist</a></h2>
<pre>
Parameters : $image_name (optional)
Returns : array (boolean)
Description : Checks if the requested image exists on the node or in the
repository. If the image exists, an array containing the image
file paths is returned. A boolean evaluation can be done on the
return value to simply determine if an image exists.</pre>
<p>
</p>
<h2><a name="get_image_size">get_image_size</a></h2>
<pre>
Parameters : $image_name (optional)
Returns : integer
Description : Returns the size of the image in megabytes.</pre>
<p>
</p>
<h2><a name="get_image_repository_search_paths">get_image_repository_search_paths</a></h2>
<pre>
Parameters : $management_node_identifier (optional)
Returns : array
Description : Returns an array containing paths on the management node where an
image may reside. The paths may contain wildcards. This is used
to attempt to locate an image on another managment node in order
to retrieve it.</pre>
<p>
</p>
<h2><a name="power_status">power_status</a></h2>
<pre>
Parameters : $domain_name (optional)
Returns : string
Description : Determines the power state of the domain. A string is returned
containing one of the following values:
* 'on'
* 'off'
* 'suspended'</pre>
<p>
</p>
<h2><a name="power_on">power_on</a></h2>
<pre>
Parameters : $domain_name (optional)
Returns : boolean
Description : Powers on the domain. Returns true if the domain was successfully
powered on or was already powered on.</pre>
<p>
</p>
<h2><a name="power_off">power_off</a></h2>
<pre>
Parameters : $domain_name
Returns : boolean
Description : Powers off the domain. Returns true if the domain was
successfully powered off or was already powered off.</pre>
<p>
</p>
<h2><a name="power_reset">power_reset</a></h2>
<pre>
Parameters : $domain_name (optional)
Returns : boolean
Description : Resets the power of the domain by powering it off and then back
on.</pre>
<p>
</p>
<h2><a name="post_maintenance_action">post_maintenance_action</a></h2>
<pre>
Parameters : none
Returns : boolean
Description : Performs tasks to the computer after it has been put into
maintenance mode.</pre>
<p>
</p>
<hr />
<h1><a name="private_methods">PRIVATE METHODS</a></h1>
<p>
</p>
<h2><a name="driver">driver</a></h2>
<pre>
Parameters : none
Returns : Libvirt driver object
Description : Returns a reference to the libvirt driver object which is created
when this libvirt.pm module is initialized.</pre>
<p>
</p>
<h2><a name="get_driver_name">get_driver_name</a></h2>
<pre>
Parameters : none
Returns : string
Description : Returns the name of the libvirt driver being used to control the
node. Example: 'KVM'</pre>
<p>
</p>
<h2><a name="get_domain_name">get_domain_name</a></h2>
<pre>
Parameters : none
Returns : string
Description : Returns the name of the domain. This name is passed to various
virsh commands. It is also the name displayed in virt-manager.
Example: 'vclv99-197:vmwarewin7-Windows764bit1846-v3'</pre>
<p>
</p>
<h2><a name="get_domain_file_base_name">get_domain_file_base_name</a></h2>
<pre>
Parameters : none
Returns : string
Description : Returns the base name for files created for the current
reservation. A file extension is not included. This file name is
used for the domain's XML definition file and it's copy on write
image file. Example: 'vclv99-37_234-v23'</pre>
<p>
</p>
<h2><a name="get_domain_xml_directory_path">get_domain_xml_directory_path</a></h2>
<pre>
Parameters : none
Returns : string
Description : Returns the directory path on the node where domain definition
XML files reside. The directory used is: '/tmp/vcl'</pre>
<p>
</p>
<h2><a name="get_domain_xml_file_path">get_domain_xml_file_path</a></h2>
<pre>
Parameters : none
Returns : string
Description : Returns the domain XML definition file path on the node.
Example: '/tmp/vcl/vclv99-37_234-v23.xml'</pre>
<p>
</p>
<h2><a name="get_master_image_directory_path">get_master_image_directory_path</a></h2>
<pre>
Parameters : none
Returns : string
Description : Returns the directory path on the node where the master image
files reside. Example: '/var/lib/libvirt/images'</pre>
<p>
</p>
<h2><a name="get_master_image_file_path">get_master_image_file_path</a></h2>
<pre>
Parameters : $image_name (optional)
Returns : string
Description : Returns the path on the node where the master image file resides.
Example:
'/var/lib/libvirt/images/vmwarelinux-RHEL54Small2251-v1.qcow2'</pre>
<p>
</p>
<h2><a name="get_copy_on_write_file_path">get_copy_on_write_file_path</a></h2>
<pre>
Parameters : none
Returns : string
Description : Returns the path on the node where the copy on write file for the
domain resides. Example:
'/var/lib/libvirt/images/vclv99-197_2251-v1.qcow2'</pre>
<p>
</p>
<h2><a name="delete_existing_domains">delete_existing_domains</a></h2>
<pre>
Parameters : none
Returns : boolean
Description : Deletes existing domains which were previously created for the
computer assigned to the current reservation.</pre>
<p>
</p>
<h2><a name="delete_domain">delete_domain</a></h2>
<pre>
Parameters : $domain_name
Returns : boolean
Description : Deletes a domain from the node.</pre>
<p>
</p>
<h2><a name="generate_domain_xml">generate_domain_xml</a></h2>
<pre>
Parameters : none
Returns : string
Description : Generates a string containing the XML definition for the domain.
</pre>
<p>
</p>
<h2><a name="get_domain_info">get_domain_info</a></h2>
<pre>
Parameters : none
Returns : hash reference
Description : Retrieves information about all of the domains defined on the
node and constructs a hash containing the information. Example:
"vclv99-197:vmwarewin7-Windows764bit1846-v3" => {
"id" => 135,
"state" => "paused"
},
"vclv99-37:vmwarewinxp-base234-v23" => {
"state" => "shut off"
}
</pre>
<p>
</p>
<h2><a name="get_domain_xml">get_domain_xml</a></h2>
<pre>
Parameters : $domain_name
Returns : hash reference
Description : Retrieves the XML definition of a domain already defined on the
node. Generates a hash using XML::Simple::XMLin.
</pre>
<p>
</p>
<h2><a name="domain_exists">domain_exists</a></h2>
<pre>
Parameters : $domain_name
Returns : boolean
Description : Determines if the domain is defined on the node.
</pre>
<p>
</p>
<h2><a name="get_snapshot_info">get_snapshot_info</a></h2>
<pre>
Parameters : $domain_name
Returns : hash reference
Description : Retrieves snapshot information for the domain specified by the
argument and constructs a hash. The hash keys are the snapshot
names. Example:
"VCL snapshot" => {
"creation_time" => "2011-12-07 16:05:50 -0500",
"state" => "shutoff"
}
</pre>
<p>
</p>
<h2><a name="create_snapshot">create_snapshot</a></h2>
<pre>
Parameters : $domain_name, $description
Returns : boolean
Description : Creates a snapshot of the domain specified by the argument.
</pre>
<p>
</p>
<h2><a name="delete_snapshot">delete_snapshot</a></h2>
<pre>
Parameters : $domain_name, $snapshot
Returns : boolean
Description : Deletes a snapshot created of the domain specified by the
argument.
</pre>
<p>
</p>
<h2><a name="get_image_size_bytes">get_image_size_bytes</a></h2>
<pre>
Parameters : $image_name (optional)
Returns : integer
Description : Returns the size of the image in bytes.
</pre>
<p>
</p>
<h2><a name="find_repository_image_file_paths">find_repository_image_file_paths</a></h2>
<pre>
Parameters : $image_name (optional)
Returns : array
Description : Locates valid image files stored in the image repository.
Searches for all files beginning with the image name and then
checks the results to remove any files which should not be
included. File extensions which are excluded: vmx, txt, xml
If multiple vmdk files are found it is assumed that the image is
one of the split vmdk formats and the <image name>.vmdk contains
the descriptor information. This file is excluded because it
causes qemu-img to fail.
</pre>
<p>
</p>
<hr />
<h1><a name="see_also">SEE ALSO</a></h1>
<p><a href="http://cwiki.apache.org/VCL/">http://cwiki.apache.org/VCL/</a>
</p>
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