Os Provisioner Documentation

Components and their relationship

The OS Provisioning service is the Hedeby component used to integrate with OS virtualization software such as N1SM, VMware or XEN in order to be able to reprovision the operating system on managed hosts. The set of hosts is fixed and will not be changed by the OS Provisioner. The only way to add or remove a host from the pool is through the interface of the virtualization software by the administrator.

The OS Provisioner is used to manage OS Dispatchers. An OS Dispatcher is an OS Provisioning container, which consists of an OS adapter and the virtualization software. An OS Dispatcher has an interface to communicate with exactly one OS Provisioner in order to report status updates and receive requests from the OS Provisioner.

The OS Provisioner service needs to be triggered from the outside to perform its tasks. For that purpose it provides an OS Provisioner Interface. This interface will be used by the Resource Provider. The current version of the OS Provisioning component does not not have a command line interface.

As a stand-alone component it will not share configuration data with other Hedeby components. All relevant data for a decision must be configured in the OS Provisioning component by a system administrator or must be discovered by examining the underlying visualization software (e.g. N1SM, VMware, XEN, ...) via the OS Dispatcher Interface.

The OS Provisioner has internal data structures reflecting the current state of all managed OS Dispatchers. The internal data structures are created at startup of the component by connecting to each managed OS Dispatcher and registering for update events.

After registering, the OS Provisioner sends a discover request to each OS Dispatcher in order to get information about host resources, possible operating systems per host resource and OS Dispatcher state information. After updating the internal states, the OS Dispatcher information data is kept up-to-date by OS Dispatcher events.

The reason the internal data is kept is to react as quickly as possible to the Resource Provider's requests. This scheme also reduces the network load, because the OS Dispatchers do not have to be queried for available resources every time the Resource Provider sends a request. A possible request such as "get a list of all possible operating systems" may cause a discovery if no operating system is currently available or a recovery is triggered by the request.

If the administrator adds a host to the Resource Provider via the CLI and this host is not known by one of the OS Dispatcher components we cannot reprovision the OS on that host. If the reprovisioning for a host is required the administrator needs to add that host through the virtualization software.

Configuration

Following configuration attributes are available for the Os Provisioning Component:

Configuration tag name	Description
Identifier	Specifies the unique name of the OSP component.
LookupInterval	Interval in seconds where the OsProvisioners tries to find new OsDispatcher components. 0 disables the search mechanism.

<config name="osp">
    <config name="Identifier">osp</config>
    <config name="LookupInterval">10</config>
</config>