Interfaces/IP addresses does not always exist when daemons start

[mattiaswal]

Current Behavior

After confd has run, dagger returns when it has performed the command using iproute2, but the kernel may not have created the interface or set the address yet, if there is a big configuration change (a lot of interfaces and ip address to be created).

This problem has been discovered during the development of the new test #776 when the containers start, they sometimes crash (presumably because the interface does not exist). In this case Finit restarts the containers and then they are happy.

However, this issue may occur in any test using the new test function put_config_dicts.

This is also the root-cause for #807.

At the same time there is an error discovered in vtysh:

R1# show ip ospf interface 
e3.8 is up
  ifindex 19, MTU 1500 bytes, BW 4294967295 Mbit 
  This interface is UNNUMBERED, Area 0.0.0.1 [NSSA]
  MTU mismatch detection: enabled
  Router ID 10.1.1.1, Network Type POINTOPOINT, Cost: 1
  Transmit Delay is 1 sec, State Point-To-Point, Priority 1
  No backup designated router on this network
  Multicast group memberships: OSPFAllRouters
  Timer intervals configured, Hello 10s, Dead 40s, Wait 40s, Retransmit 5
    Hello due in 3.076s
  Neighbor Count is 1, Adjacent neighbor count is 1
e6 is up
  ifindex 7, MTU 1500 bytes, BW 4294967295 Mbit 
  Internet Address 10.1.1.101/24, Broadcast 10.1.1.255, Area 0.0.0.1 [NSSA]
  MTU mismatch detection: enabled
  Router ID 10.1.1.1, Network Type BROADCAST, Cost: 1
  Transmit Delay is 1 sec, State Backup, Priority 1
  Designated Router (ID) 192.168.100.1 Interface Address 10.1.1.100/24
  Backup Designated Router (ID) 10.1.1.1, Interface Address 10.1.1.101
  Multicast group memberships: OSPFAllRouters OSPFDesignatedRouters
  Timer intervals configured, Hello 10s, Dead 40s, Wait 40s, Retransmit 5
    Hello due in 3.076s
  Neighbor Count is 1, Adjacent neighbor count is 1

We expect e4.8 in this output too, but at the time ospfd starts it seemingly did not exist.

The problem is not fixed by just restarting ospfd, zebra also needs to be restarted, then the interfaces appear in OSPF, so there may be a FRR bug here also.