sonic-bgpcfgd build fails in the absence of Python 2, as it attempts to explicitly call sonic-cfggen using `/usr/bin/python2.7`. Also, it attempts to call sonic-cfggen using a local, relative path. Since the sonic-config-engine package is not installed, neither are its dependencies.
Now, we configure the Python 3 sonic-config-engine as a dependency of sonic-bgpcfgd, which ensures the Python 3 sonic-config-engine package and its dependencies are installed before sonic-bgpcfgd is built/tested.
**- Why I did it**
FRR introduced [next hop tracking](http://docs.frrouting.org/projects/dev-guide/en/latest/next-hop-tracking.html) functionality.
That functionality requires resolving BGP neighbors before setting BGP connection (or explicit ebgp-multihop command). Sometimes (BGP MONITORS) our neighbors are not directly connected and sessions are IBGP. In this case current configuration prevents FRR to establish BGP connections. Reason would be "waiting for NHT". To fix that we need either add static routes for each not-directly connected ibgp neighbor, or enable command `ip nht resolve-via-default`
**- How I did it**
Put `ip nht resolve-via-default` into the config
**- How to verify it**
Build an image. Enable BGP_MONITOR entry and check that entry is Established or Connecting in FRR
Co-authored-by: Pavel Shirshov <pavel.contrib@gmail.com>
Natural sorting of SONiC config gen output consumes lot of CPU cycles.
The sole use of natsorted was to make test comparison easier and so,
the natsorting logic is now relocated to the test suite. As a result
sonic-cfggen gained nearly 1 sec per call since we no longer import
natsorted module!
singed-off-by: Tamer Ahmed <tamer.ahmed@microsoft.com>
