The govppmux
is a Core Agent Plugin which allows other plugins to access VPP
independently on each other by means of connection multiplexing.
Any plugin (core or external) that interacts with VPP can ask govppmux
to get its own, potentially customized, communication channel to running VPP instance.
Behind the scenes, all channels share the same connection created during the plugin
initialization using govpp core.
API
Connection
Parameters of the VPP connection are fixed and cannot be configured. GoVPP connects to that instance of VPP which uses the default shared memory segment prefix. This is because it is assumed that there is really only a single VPP running in a sand-boxed environment together with the agent (e.g. through containerization)
Multiplexing
NewAPIChannel
returns a new API channel for communication with VPP via govpp core.
It uses default buffer sizes for the request and reply Go channels (by default both are 100 messages long).
If it is expected that the VPP may get overloaded at peak loads, for example if the user plugin
sends configuration requests in bulks, then it is recommended to use NewAPIChannelBuffered
and increase the buffer size for requests appropriately. Similarly, NewAPIChannelBuffered
allows
to configure the size of the buffer for responses. This is also useful since the buffer for responses
is also used to carry VPP notifications and statistics which may temporarily rapidly grow in size
and frequency. By increasing the reply channel size, the probability of dropping messages from VPP
decreases at the cost of increased memory footprint.
Example
The following example shows how to dump VPP interfaces using a multi-response request:
// Create a new VPP channel with the default configuration.
plugin.vppCh, err = govppmux.NewAPIChannel()
if err != nil {
// Handle error condition...
}
// Close VPP channel.
defer safeclose.Close(plugin.vppCh)
req := &interfaces.SwInterfaceDump{}
reqCtx := plugin.vppCh.SendMultiRequest(req)
for {
msg := &interfaces.SwInterfaceDetails{}
stop, err := reqCtx.ReceiveReply(msg)
if err != nil {
// Handle error condition...
}
// Break out of the loop in case there are no more messages.
if stop {
break
}
log.Info("Found interface with sw_if_index=", msg.SwIfIndex)
// Process the message...
}