[load_minigraph] Delay pfcwd start until the buffer templates are ren…

…dered (sonic-net#1937)

Signed-off-by: Neetha John <nejo@microsoft.com>

Fixes sonic-net#9292

What I did
Pfcwd was not getting started after executing load_minigraph after the changes done in sonic-net#1508. This was because the PORT_QOS_MAP table is not yet present in config db (this gets populated only after the buffer templates are rendered) at the time we try to start pfcwd and hence the 'pfc_enable' field will always be empty and we skip writing PFC_WD table entries to config db.

How I did it
Delay pfcwd start until the buffer templates are rendered

How to verify it
Issue "config load_minigraph" with the changes and ensure that pfcwd is started on all active ports

config/main.py

@@ -1515,11 +1515,6 @@ def load_minigraph(db, no_service_restart):
         clicommon.run_command(command, display_cmd=True)
         client.set(config_db.INIT_INDICATOR, 1)
 
-    # get the device type
-    device_type = _get_device_type()
-    if device_type != 'MgmtToRRouter' and device_type != 'MgmtTsToR' and device_type != 'EPMS':
-        clicommon.run_command("pfcwd start_default", display_cmd=True)
-
     # Update SONiC environmnet file
     update_sonic_environment()
 
@@ -1535,6 +1530,11 @@ def load_minigraph(db, no_service_restart):
     # generate QoS and Buffer configs
     clicommon.run_command("config qos reload --no-dynamic-buffer", display_cmd=True)
 
+    # get the device type
+    device_type = _get_device_type()
+    if device_type != 'MgmtToRRouter' and device_type != 'MgmtTsToR' and device_type != 'EPMS':
+        clicommon.run_command("pfcwd start_default", display_cmd=True)
+
     # Write latest db version string into db
     db_migrator='/usr/local/bin/db_migrator.py'
     if os.path.isfile(db_migrator) and os.access(db_migrator, os.X_OK):

tests/config_test.py

@@ -21,8 +21,8 @@
 load_minigraph_command_output="""\
 Stopping SONiC target ...
 Running command: /usr/local/bin/sonic-cfggen -H -m --write-to-db
-Running command: pfcwd start_default
 Running command: config qos reload --no-dynamic-buffer
+Running command: pfcwd start_default
 Restarting SONiC target ...
 Reloading Monit configuration ...
 Please note setting loaded from minigraph will be lost after system reboot. To preserve setting, run `config save`.