Creating a new Bond interface from scratch works like a charm but adding a VIF once the bond is already established leads to an OSError exception.
```
[ interfaces bonding bond0 ]
DEBUG/bond0 write '0' > '/sys/class/net/bond0/bonding/miimon'
DEBUG/bond0 read '' < '/sys/class/net/bond0/bonding/arp_ip_target'
DEBUG/bond0 write 'sdfasdf' > '/sys/class/net/bond0/ifalias'
DEBUG/bond0 write '1' > '/proc/sys/net/ipv4/conf/bond0/link_filter'
DEBUG/bond0 write 'layer2' > '/sys/class/net/bond0/bonding/xmit_hash_policy'
DEBUG/bond0 write '30000' > '/proc/sys/net/ipv4/neigh/bond0/base_reachable_time_ms'
DEBUG/bond0 write '1' > '/proc/sys/net/ipv4/conf/bond0/arp_filter'
DEBUG/bond0 write '0' > '/proc/sys/net/ipv4/conf/bond0/arp_accept'
DEBUG/bond0 write '0' > '/proc/sys/net/ipv4/conf/bond0/arp_announce'
DEBUG/bond0 write '0' > '/proc/sys/net/ipv4/conf/bond0/arp_ignore'
DEBUG/bond0 write '0' > '/proc/sys/net/ipv4/conf/bond0/proxy_arp'
DEBUG/bond0 write '0' > '/proc/sys/net/ipv4/conf/bond0/proxy_arp_pvlan'
DEBUG/bond0 write '1500' > '/sys/class/net/bond0/mtu'
DEBUG/bond0 cmd 'ip link set dev bond0 down'
DEBUG/eth2 cmd 'ip link set dev eth2 down'
DEBUG/bond0 write '+eth2' > '/sys/class/net/bond0/bonding/slaves'
OSError: [Errno 16] Device or resource busy
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/usr/libexec/vyos/conf_mode/interfaces-bonding.py", line 511, in <module>
apply(c)
File "/usr/libexec/vyos/conf_mode/interfaces-bonding.py", line 457, in apply
b.add_port(intf)
File "/usr/lib/python3/dist-packages/vyos/ifconfig.py", line 1519, in add_port
.format(self._ifname), '+' + interface)
File "/usr/lib/python3/dist-packages/vyos/ifconfig.py", line 153, in _write_sysfs
f.write(str(value))
OSError: [Errno 16] Device or resource busy
[[interfaces bonding bond0]] failed
Commit failed
```
Problem is somehow related to the solution implemented in T1992.