WaitForNetIP and docker-backed vcsim VM

[BrianMMcClain]

Howdy!

This question may just be me overlooking something, so I apologize if I am :)

The tl;dr is that I'm experimenting with backing a VM with a docker container to integrate with another existing product and ran into a small speedbump with the call to WaitForNetIP, where it hangs until timeout. Alternatively, WaitForIP returns the correct IP immediately. In my case, the VM for both calls has one NIC

WaitForNetIP, if my understanding is correct, does the following...

1. pulls the config.hardware.device of the VM
2. stores a list of MAC addresses for each BaseVirtualEthernetCard
3. pulls the guest.net property of the VM
4. Iterates over each NIC, comparing them to the list of MAC addresses stored in step 2
5. Stores the IP for each found MAC

(I think I'm over simplifying it, and I could be misunderstanding here)

The first thing to address was that the MAC reported by config.hardware.device and guest.net differ, which makes sense reading the wiki, I saw:

The VM guest field is populated with the container's IP address and MAC address

The MAC reported from the VM is VMware MAC, while the one from the guest.net property is from Docker.

However, if I create a VM where the MACs match, it still continues to hang. I believe the spot I'm struggling with right now is this block in virtual_machine.go

if mac == "" || nic.IpConfig == nil {
    continue
}

where mac is populated correctly, but nic.IpConfig is nil, so it skips the following block which parses and stores the IP address from the NIC.

I figured it wouldn't hurt to drop a message here and see if this scenario is a supported one, or if this field isn't populated from vcsim. If the latter, would this be something that would be a good PR? I'm still reading through the code so haven't seen why this is the case, but happy to follow through. Thanks!

[dougm]

Hey @BrianMMcClain ! Thanks for the details and sorry for the delay. The patch below should fix, I'll update the tests and open a PR soon (need to resolve another issue first).

diff --git a/simulator/container.go b/simulator/container.go
index 08f8f7ed..650c1997 100644
--- a/simulator/container.go
+++ b/simulator/container.go
@@ -114,6 +114,18 @@ func (c *container) inspect(vm *VirtualMachine) error {
                        net := &vm.Guest.Net[0]
                        net.IpAddress = []string{s.IPAddress}
                        net.MacAddress = s.MacAddress
+                       net.IpConfig = &types.NetIpConfigInfo{
+                               IpAddress: []types.NetIpConfigInfoIpAddress{
+                                       {IpAddress: s.IPAddress},
+                               },
+                       }
+               }
+
+               for _, d := range vm.Config.Hardware.Device {
+                       if eth, ok := d.(types.BaseVirtualEthernetCard); ok {
+                               eth.GetVirtualEthernetCard().MacAddress = s.MacAddress
+                               break
+                       }
                }
        }

[BrianMMcClain]

Oh this is awesome, thank you! I'll give this a spin and let you know how it goes :)

[BrianMMcClain]

Great news, this was exactly what I needed, thank you! :)

[dougm]

Nice! PR opened: #3034