8606af13c7
* This whitespace-only patch reflows the docs (mostly) to 79 columns, except for unbreakable links. * The glossary also had a missing newline at the end of the file. Change-Id: I8a6c741555de5ed62990fbb2c034651f73327784 Signed-off-by: Jan Gutter <jan.gutter@netronome.com>
65 lines
2.7 KiB
ReStructuredText
65 lines
2.7 KiB
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================
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Host Information
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================
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To enable negotiation of features between a service host (typically a compute
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node) and the network provider host, os-vif exposes some objects that describe
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the host running the plugins.
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Host Information Objects
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========================
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The following objects encode the information about the service host.
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HostInfo
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--------
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This class provides information about the host as a whole. This currently means
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a list of plugins installed on the host. In the future this may include further
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information about the host OS state.
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HostPluginInfo
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--------------
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This class provides information about the capabilities of a single os-vif
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plugin implementation that is installed on the host. This currently means a
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list of VIF objects that the plugin is capable of consuming. In the future this
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may include further information about resources on the host that the plugin
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can/will utilize. While many plugins will only ever support a single VIF
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object, it is permitted to support multiple different VIF objects. An example
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would be openvswitch which can use the same underlying host network
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functionality to configure a VM in several different ways.
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HostVIFInfo
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-----------
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This class provides information on a single VIF object that is supported by a
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plugin. This will include the versioned object name and the minimum and maximum
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versions of the object that can be consumed.
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It is the responsibility of the network provider to ensure that it only sends
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back a serialized VIF object that satisfies the minimum and maximum version
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constraints indicated by the plugin. Objects outside of this version range will
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be rejected with a fatal error.
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Negotiating networking
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======================
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When a service host wants to create a network port, it will first populate an
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instance of the HostInfo class, to describe all the plugins installed on the
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host. It will then serialize this class to JSON and send it to the network
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manager host. The network manager host will deserialize it back into a HostInfo
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object. This can then be passed down into the network driver which can use it
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to decide how to configure the network port.
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If the os-vif version installed on the network host is older than that on the
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service host, it may not be able to deserialize the HostInfo class. In this
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case it should reply with an error to the service host. The error message
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should report the maximum version of the HostInfo class that is supported. the
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service host should then backlevel its HostInfo object to that version before
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serializing it and re-trying the port creation request.
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The mechanism or transport for passing the plugin information between the
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network and service hosts is left undefined. It is upto the user of os-vif to
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decide upon the appropriate approach.
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