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67e0468b94
Signed-off-by: Peter Krempa <pkrempa@redhat.com> Reviewed-by: Ján Tomko <jtomko@redhat.com>
57 lines
3.1 KiB
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57 lines
3.1 KiB
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=====================
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Terminology and goals
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=====================
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To avoid ambiguity about the terms used, here are the definitions for some of
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the specific concepts used in libvirt documentation:
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- a **node** is a single physical machine
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- an **hypervisor** is a layer of software allowing to virtualize a node in a
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set of virtual machines with possibly different configurations than the node
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itself
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- a **domain** is an instance of an operating system (or subsystem in the case
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of container virtualization) running on a virtualized machine provided by the
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hypervisor
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Now we can define the goal of libvirt: **to provide a common and stable layer
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sufficient to securely manage domains on a node, possibly remote**.
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As a result, libvirt should provide all APIs needed to do the management, such
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as: provision, create, modify, monitor, control, migrate and stop the domains -
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within the limits of the support of the hypervisor for those operations. Not all
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hypervisors provide the same operations; but if an operation is useful for
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domain management of even one specific hypervisor it is worth providing in
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libvirt. Multiple nodes may be accessed with libvirt simultaneously, but the
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APIs are limited to single node operations. Node resource operations which are
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needed for the management and provisioning of domains are also in the scope of
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the libvirt API, such as interface setup, firewall rules, storage management and
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general provisioning APIs. Libvirt will also provide the state monitoring APIs
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needed to implement management policies, obviously checking domain state but
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also exposing local node resource consumption.
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This implies the following sub-goals:
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- All API can be carried remotely though secure APIs
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- While most API will be generic in term of hypervisor or Host OS, some API may
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be targeted to a single virtualization environment as long as the semantic
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for the operations from a domain management perspective is clear
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- the API should allow to do efficiently and cleanly all the operations needed
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to manage domains on a node, including resource provisioning and setup
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- the API will not try to provide high level virtualization policies or
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multi-nodes management features like load balancing, but the API should be
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sufficient so they can be implemented on top of libvirt
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- stability of the API is a big concern, libvirt should isolate applications
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from the frequent changes expected at the lower level of the virtualization
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framework
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- the node being managed may be on a different physical machine than the
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management program using libvirt, to this effect libvirt supports remote
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access, but should only do so by using secure protocols.
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- libvirt will provide APIs to enumerate, monitor and use the resources
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available on the managed node, including CPUs, memory, storage, networking,
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and NUMA partitions.
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So libvirt is intended to be a building block for higher level management tools
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and for applications focusing on virtualization of a single node (the only
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exception being domain migration between node capabilities which involves more
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than one node).
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