[config/show] Add command to control pending FIB suppression (#2495)

* [config/show] Add command to control pending FIB suppression

What I did
I added a command config suppress-pending-fib that will allow user to enable/disable this feature.
Once it is enabled, BGP will wait for route to be programmed to HW before announcing the route to the peers.

I also added a corresponding show command that prints the status of this feature.

config/main.py

@@ -1793,7 +1793,7 @@ def load_minigraph(db, no_service_restart, traffic_shift_away, override_config,
                 cfggen_namespace_option = " -n {}".format(namespace)
             clicommon.run_command(db_migrator + ' -o set_version' + cfggen_namespace_option)
 
-    # Keep device isolated with TSA 
+    # Keep device isolated with TSA
     if traffic_shift_away:
         clicommon.run_command("TSA", display_cmd=True)
         if override_config:
@@ -2006,9 +2006,21 @@ def synchronous_mode(sync_mode):
               config reload -y \n
     Option 2. systemctl restart swss""" % sync_mode)
 
+#
+# 'suppress-fib-pending' command ('config suppress-fib-pending ...')
+#
+@config.command('suppress-fib-pending')
+@click.argument('state', metavar='<enabled|disabled>', required=True, type=click.Choice(['enabled', 'disabled']))
+@clicommon.pass_db
+def suppress_pending_fib(db, state):
+    ''' Enable or disable pending FIB suppression. Once enabled, BGP will not advertise routes that are not yet installed in the hardware '''
+
+    config_db = db.cfgdb
+    config_db.mod_entry('DEVICE_METADATA' , 'localhost', {"suppress-fib-pending" : state})
+
 #
 # 'yang_config_validation' command ('config yang_config_validation ...')
-# 
+#
 @config.command('yang_config_validation')
 @click.argument('yang_config_validation', metavar='<enable|disable>', required=True)
 def yang_config_validation(yang_config_validation):

doc/Command-Reference.md

@@ -2055,6 +2055,26 @@ This command displays the routing policy that takes precedence over the other ro
       Exit routemap
   ```
 
+**show suppress-fib-pending**
+
+This command is used to show the status of suppress pending FIB feature.
+When enabled, BGP will not advertise routes which aren't yet offloaded.
+
+- Usage:
+  ```
+  show suppress-fib-pending
+  ```
+
+- Examples:
+  ```
+  admin@sonic:~$ show suppress-fib-pending
+  Enabled
+  ```
+  ```
+  admin@sonic:~$ show suppress-fib-pending
+  Disabled
+  ```
+
 Go Back To [Beginning of the document](#) or [Beginning of this section](#bgp)
 
 ### BGP config commands
@@ -2147,6 +2167,24 @@ This command is used to remove particular IPv4 or IPv6 BGP neighbor configuratio
   admin@sonic:~$ sudo config bgp remove neighbor SONIC02SPINE
   ```
 
+**config suppress-fib-pending**
+
+This command is used to enable or disable announcements of routes not yet installed in the HW.
+Once enabled, BGP will not advertise routes which aren't yet offloaded.
+
+- Usage:
+  ```
+  config suppress-fib-pending <enabled|disabled>
+  ```
+
+- Examples:
+  ```
+  admin@sonic:~$ sudo config suppress-fib-pending enabled
+  ```
+  ```
+  admin@sonic:~$ sudo config suppress-fib-pending disabled 
+  ```
+
 Go Back To [Beginning of the document](#) or [Beginning of this section](#bgp)
 
 ## Console

show/main.py

@@ -2093,6 +2093,17 @@ def peer(db, peer_ip):
     click.echo(tabulate(bfd_body, bfd_headers))
 
 
+# 'suppress-fib-pending' subcommand ("show suppress-fib-pending")
+@cli.command('suppress-fib-pending')
+@clicommon.pass_db
+def suppress_pending_fib(db):
+    """ Show the status of suppress pending FIB feature """
+
+    field_values = db.cfgdb.get_entry('DEVICE_METADATA', 'localhost')
+    state = field_values.get('suppress-fib-pending', 'disabled').title()
+    click.echo(state)
+
+
 # Load plugins and register them
 helper = util_base.UtilHelper()
 helper.load_and_register_plugins(plugins, cli)

tests/suppress_pending_fib_test.py

@@ -0,0 +1,34 @@
+from click.testing import CliRunner
+
+import config.main as config
+import show.main as show
+from utilities_common.db import Db
+
+
+class TestSuppressFibPending:
+    def test_synchronous_mode(self):
+        runner = CliRunner()
+
+        db = Db()
+
+        result = runner.invoke(config.config.commands['suppress-fib-pending'], ['enabled'], obj=db)
+        print(result.output)
+        assert result.exit_code == 0
+        assert db.cfgdb.get_entry('DEVICE_METADATA' , 'localhost')['suppress-fib-pending'] == 'enabled'
+
+        result = runner.invoke(show.cli.commands['suppress-fib-pending'], obj=db)
+        assert result.exit_code == 0
+        assert result.output == 'Enabled\n'
+
+        result = runner.invoke(config.config.commands['suppress-fib-pending'], ['disabled'], obj=db)
+        print(result.output)
+        assert result.exit_code == 0
+        assert db.cfgdb.get_entry('DEVICE_METADATA' , 'localhost')['suppress-fib-pending'] == 'disabled'
+
+        result = runner.invoke(show.cli.commands['suppress-fib-pending'], obj=db)
+        assert result.exit_code == 0
+        assert result.output == 'Disabled\n'
+
+        result = runner.invoke(config.config.commands['suppress-fib-pending'], ['invalid-input'], obj=db)
+        print(result.output)
+        assert result.exit_code != 0