Enabling/fixing debug/undebug feature for quagga/frr

[rodnymolina]

Note: PR depends on PR/1714

With this PR I'm taking care of the following issues:

   * Fixed debug/undebug cli commands for bgp and zebra processes.
   * Added a new cli command to activate/deactivate the generation of debuging info.
   * Added two separated command structures for Quagga and FRR routing-stacks -- notice that they don't fully match.
   * Also notice that FRR's approach doesn't require the explicit definition of all subcommands, as we're passing this information to FRR's vtysh daemon.

New debug/undebug stanzas now look like this:

Quagga example

admin@lnos-x1-a-csw01:~$ debug ?
Usage: debug [OPTIONS] COMMAND [ARGS]...

SONiC command line - 'debug' command

Options:
  -?, -h, --help  Show this message and exit.

Commands:
  bgp      debug bgp events
  disable  disable debugging for routing events
  enable   enable debugging for routing events
  zebra    debug bgp events

admin@lnos-x1-a-csw01:~$ debug bgp ?
Usage: debug bgp [OPTIONS] COMMAND [ARGS]...

debug bgp events

Options:
  -?, -h, --help  Show this message and exit.

Commands:
  as4         debug bgp AS4 actions
  events      debug bgp events
  filters     debug bgp filters
  fsm         debug bgp fsm
  keepalives  debug bgp keepalives
  updates     debug bgp updates
  zebra       debug bgp zebra messages

admin@lnos-x1-a-csw01:~$ debug zebra ?
Usage: debug zebra [OPTIONS] COMMAND [ARGS]...

debug bgp events

Options:
  -?, -h, --help  Show this message and exit.

Commands:
  events  debug zebra events
  fpm     debug zebra fpm events
  kernel  debug zebra's kernel-interface events
  packet  debug zebra packets
  rib     debug zebra RIB events

FRR example

admin@lnos-x1-a-csw02:~$ debug ?
Usage: debug [OPTIONS] COMMAND [ARGS]...

  SONiC debugging commands for routing events

Options:
  -?, -h, --help  Show this message and exit.

Commands:
  bgp      Debug BGP information
  disable  Disable debugging for routing events
  enable   Enable debugging for routing events
  zebra    Debug Zebra information

admin@lnos-x1-a-csw02:~$ debug bgp ?
Command: sudo vtysh -c "debug bgp ?"
  allow-martians   BGP allow martian next hops
  as4              BGP AS4 actions
  bestpath         BGP bestpath
  keepalives       BGP keepalives
  neighbor-events  BGP Neighbor Events
  nht              BGP nexthop tracking events
  update-groups    BGP update-groups
  updates          BGP updates
  zebra            BGP Zebra messages

admin@lnos-x1-a-csw02:~$ debug zebra ?
Command: sudo vtysh -c "debug zebra ?"
  events       Debug option set for zebra events
  fpm          Debug zebra FPM events
  kernel       Debug option set for zebra between kernel interface
  mpls         Debug option set for zebra MPLS LSPs
  nht          Debug option set for zebra next hop tracking
  packet       Debug option set for zebra packet
  pseudowires  Debug option set for zebra pseudowires
  rib          Debug RIB events

UT's
====

admin@lnos-x1-a-csw02:~$ debug enable
Command: sudo vtysh -c "configure terminal" -c "log syslog debugging"

admin@lnos-x1-a-csw02:~$ debug bgp ?
Command: sudo vtysh -c "debug bgp ?"
  allow-martians   BGP allow martian next hops
  as4              BGP AS4 actions
  bestpath         BGP bestpath
  keepalives       BGP keepalives
  neighbor-events  BGP Neighbor Events
  nht              BGP nexthop tracking events
  update-groups    BGP update-groups
  updates          BGP updates
  zebra            BGP Zebra messages

admin@lnos-x1-a-csw02:~$ debug bgp keepalive
Command: sudo vtysh -c "debug bgp keepalive"
BGP keepalives debugging is on

admin@lnos-x1-a-csw02:~$ sudo tail -f /var/log/syslog  [ destination log file is as per /etc/rsyslog.d/00-sonic.conf ]
...
May  9 23:51:48.525961 lnos-x1-a-csw02 DEBUG bgpd[65]: fc00:2:2::2 sending KEEPALIVE
May  9 23:51:48.526019 lnos-x1-a-csw02 DEBUG bgpd[65]: 10.2.2.2 sending KEEPALIVE
May  9 23:51:48.526054 lnos-x1-a-csw02 DEBUG bgpd[65]: fc00:2:2::2 KEEPALIVE rcvd
May  9 23:51:48.526123 lnos-x1-a-csw02 DEBUG bgpd[65]: 10.2.2.2 KEEPALIVE rcvd
...

admin@lnos-x1-a-csw02:~$ undebug bgp keepalive
Command: sudo vtysh -c "no debug bgp keepalive"
BGP keepalives debugging is off

[nikos-github]

The comments in #222 which you haven't followed, still apply.

[rodnymolina]

I did took #222 into account, and that's one of the reasons i removed all FRR related debug commands. Only Quagga debug commands are exposed, as this one is not using our knob to pass cli-commands transparently to the backend.

Concerning the 'undebug' vs 'no debug', we can discuss if we want to migrate in the future towards the 'no debug' stanza, but what we have today is 'undebug', and this one is broken, so this PR is simply fixing what is already out there.

[nikos-github]

If undebug is broken, then best not to fix it since it is removed in FRR.

I recommend following the same approach you have for FRR, for quagga as well. It has made the code and functionality much better.

Ultimately sonic MS team is to bless this.

[rodnymolina]

Right, my goal is to extend my FRR changes to Quagga too, but that will require more changes in more repos. This current patch is already involving changes in three different repos. Quagga changes can come later.

We should fix 'debug/undebug' cli now. If the cli implemented by the backend services change, we can later decide to update our front-end cli for end-to-end consistency, or simply leave it the way it is today as we wouldn't be breaking any functionality thanks to Click wrappers.