update main module with vlan endpoint implementation

[pperiyasamy]

This adds the following:

1. update main module with config parsing, adding endpoint, starting grpc server with endpoint and registering endpoint with NSM registry.
2. update ifconfig server chain element with a goroutine which would configure vlan sub interface on the vpp instance for every client connection.
3. initialise kernel server element with parent interface name, add vlan chain element to assign unique vlan id for every client connection and enable sriov token server element with the share token id for VF scenario.

Signed-off-by: Periyasamy Palanisamy [email protected]

[pperiyasamy]

/cc @JanScheurich

[JanScheurich]

This seems to be in the name assigned to the parent interface. Linux interface names are limited to 15 characters. The default name here seems too long. Can it be shortened?

[pperiyasamy]

yes jan, done.

[edwarnicke]

Usually this parameters is the name of the NSE... I would suggest considering not using it as the interface name, but rather generating that.

[pperiyasamy]

sure, done.

[JanScheurich]

It's not clear to me when and how the parent interface is actually created and injected into the NSE pod.
It can't really happen at registration of the NSE or its grpc handler, right?
Does it happen implicitly by the forwarder when the first client connects? How can the ifServer go-routine be sure that the parent interface is already successfully injected by the forwarder when it processes the first "add" operation?

[pperiyasamy]

This go routine is started at endpoint bringup as part of creation of ifconfig server chain element (line 65-69). The teardown happens when the endpoint is deleted.
This waits for ifOp entry on the ifOps channel. The write of ifOp happens at Request/Close method of ifconfig server chain element which happens for every NS client. so this go routine is run after all the elements (ipam, vlan etc.) in the chain are executed which is sufficient (as connection obj holds everything) to create vlan sub interface and configure ip, route etc. The parent interface is injected by forwarder, that's why this go routine is made to sleep for 1 sec in a busy wait when parent interface is not found.

[JanScheurich]

Oh, I didn't notice the sleep 1 loop. That's how you address the race. Should there be some "timeout" in case the parent interface never shows up and return an error?

[edwarnicke]

I would suggest using netlink.LinkSubscribe instead of a Sleep. Whenever possible, subscribe to events, don't poll :)

Something like

done := make(<-chan struct{})
defer close(done)

ch := make(chan<- LinkUpdate,1)
defer close(ch)

if err := netlink.LinkSubscribe(ch,done);err != nil { ... }
parentIf, err := netlink.LinkByName(i.parentIfName)
if err != nil {
  for _, event := range ch {
      // Check for your interface appearing in LinkUpdate and break
  }
}

[pperiyasamy]

yes @edwarnicke , this is a good approach, changed it now, please have look.