Synnefo » snf-ganeti

Non bridged instances support

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Current State and shortcomings

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Currently each instance NIC must be connected to a bridge, and if the bridge is

not specified the default cluster one is used. This makes it impossible to use

the vif-route xen network scripts, or other alternative mechanisms that don't

need a bridge to work.

Proposed changes

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The new "mode" network parameter will distinguish between bridged interfaces

and routed ones.

When mode is "bridge" the "link" parameter will contain the bridge the instance

should be connected to, effectively making things as today. The value has been

migrated from a nic field to a parameter to allow for an easier manipulation of

the cluster default.

When mode is "route" the ip field of the interface will become mandatory, to

allow for a route to be set. In the future we may want also to accept multiple

IPs or IP/mask values for this purpose. We will evaluate possible meanings of

the link parameter to signify a routing table to be used, which would allow for

insulation between instance groups (as today happens for different bridges).

For now we won't add a parameter to specify which network script gets called

for which instance, so in a mixed cluster the network script must be able to

handle both cases. The default kvm vif script will be changed to do so. (Xen

doesn't have a ganeti provided script, so nothing will be done for that

hypervisor)