Add show command for BFD sessions (sonic-net#1942)

What I did
Add show command for BFD sessions.

How I did it
Add show command for BFD session and unit tests.

How to verify it
Verify the show command locally and unit test passes.

doc/Command-Reference.md

@@ -28,6 +28,8 @@
 * [ARP & NDP](#arp--ndp)
   * [ARP show commands](#arp-show-commands)
   * [NDP show commands](#ndp-show-commands)
+* [BFD](#bfd)
+  * [BFD show commands](#bfd-show-commands)
 * [BGP](#bgp)
   * [BGP show commands](#bgp-show-commands)
   * [BGP config commands](#bgp-config-commands)
@@ -1546,6 +1548,45 @@ This command displays either all the IPv6 neighbor mac addresses, or for a parti
 
 Go Back To [Beginning of the document](#) or [Beginning of this section](#arp--ndp)
 
+## BFD
+
+### BFD show commands
+
+**show bfd summary**
+
+This command displays the state and key parameters of all BFD sessions.
+
+- Usage:
+  ```
+  show bgp summary
+  ```
+- Example:
+  ```
+  >> show bfd summary
+  Total number of BFD sessions: 3
+  Peer Addr    Interface    Vrf      State    Type          Local Addr      TX Interval    RX Interval    Multiplier  Multihop
+  -----------  -----------  -------  -------  ------------  ------------  -------------  -------------  ------------  ----------
+  10.0.1.1     default      default  DOWN     async_active  10.0.0.1                300            500             3  true
+  10.0.2.1     Ethernet12   default  UP       async_active  10.0.0.1                200            600             3  false
+  2000::10:1   default      default  UP       async_active  2000::1                 100            700             3  false
+  ```
+
+**show bfd peer**
+
+This command displays the state and key parameters of all BFD sessions that match an IP address.
+
+- Usage:
+  ```
+  show bgp peer <peer-ip>
+  ```
+- Example:
+  ```
+  >> show bfd peer 10.0.1.1
+  Total number of BFD sessions for peer IP 10.0.1.1: 1
+  Peer Addr    Interface    Vrf      State    Type          Local Addr      TX Interval    RX Interval    Multiplier  Multihop
+  -----------  -----------  -------  -------  ------------  ------------  -------------  -------------  ------------  ----------
+  10.0.1.1     default      default  DOWN     async_active  10.0.0.1                300            500             3  true
+  ```
 
 ## BGP
 

show/main.py

@@ -1701,6 +1701,67 @@ def ztp(status, verbose):
        cmd = cmd + " --verbose"
     run_command(cmd, display_cmd=verbose)
 
+
+#
+# 'bfd' group ("show bfd ...")
+#
+@cli.group(cls=clicommon.AliasedGroup)
+def bfd():
+    """Show details of the bfd sessions"""
+    pass
+
+# 'summary' subcommand ("show bfd summary")
+@bfd.command()
+@clicommon.pass_db
+def summary(db):
+    """Show bfd session information"""
+    bfd_headers = ["Peer Addr", "Interface", "Vrf", "State", "Type", "Local Addr",
+                "TX Interval", "RX Interval", "Multiplier", "Multihop"]
+
+    bfd_keys = db.db.keys(db.db.STATE_DB, "BFD_SESSION_TABLE|*")
+
+    click.echo("Total number of BFD sessions: {}".format(0 if bfd_keys is None else len(bfd_keys)))
+
+    bfd_body = []
+    if bfd_keys is not None:
+        for key in bfd_keys:
+            key_values = key.split('|')
+            values = db.db.get_all(db.db.STATE_DB, key)
+            bfd_body.append([key_values[3], key_values[2], key_values[1], values["state"], values["type"], values["local_addr"],
+                                values["tx_interval"], values["rx_interval"], values["multiplier"], values["multihop"]])
+
+    click.echo(tabulate(bfd_body, bfd_headers))
+
+
+# 'peer' subcommand ("show bfd peer ...")
+@bfd.command()
+@clicommon.pass_db
+@click.argument('peer_ip', required=True)
+def peer(db, peer_ip):
+    """Show bfd session information for BFD peer"""
+    bfd_headers = ["Peer Addr", "Interface", "Vrf", "State", "Type", "Local Addr",
+                "TX Interval", "RX Interval", "Multiplier", "Multihop"]
+
+    bfd_keys = db.db.keys(db.db.STATE_DB, "BFD_SESSION_TABLE|*|{}".format(peer_ip))
+    delimiter = db.db.get_db_separator(db.db.STATE_DB)
+
+    if bfd_keys is None or len(bfd_keys) == 0:
+        click.echo("No BFD sessions found for peer IP {}".format(peer_ip))
+        return
+
+    click.echo("Total number of BFD sessions for peer IP {}: {}".format(peer_ip, len(bfd_keys)))
+
+    bfd_body = []
+    if bfd_keys is not None:
+        for key in bfd_keys:
+            key_values = key.split(delimiter)
+            values = db.db.get_all(db.db.STATE_DB, key)
+            bfd_body.append([key_values[3], key_values[2], key_values[1], values.get("state"), values.get("type"), values.get("local_addr"),
+                                values.get("tx_interval"), values.get("rx_interval"), values.get("multiplier"), values.get("multihop")])
+
+    click.echo(tabulate(bfd_body, bfd_headers))
+
+
 # Load plugins and register them
 helper = util_base.UtilHelper()
 helper.load_and_register_plugins(plugins, cli)

tests/show_bfd_test.py

@@ -0,0 +1,98 @@
+import os
+import sys
+from click.testing import CliRunner
+from swsscommon.swsscommon import SonicV2Connector
+from utilities_common.db import Db
+
+import show.main as show
+
+test_path = os.path.dirname(os.path.abspath(__file__))
+mock_db_path = os.path.join(test_path, "bfd_input")
+
+class TestShowBfd(object):
+    @classmethod
+    def setup_class(cls):
+        print("SETUP")
+        os.environ["UTILITIES_UNIT_TESTING"] = "1"
+
+    def set_db_values(self, db, key, kvs):
+        for field, value in kvs.items():
+            db.set(db.STATE_DB, key, field, value)
+
+    def test_bfd_show(self):
+        runner = CliRunner()
+        db = Db()
+        dbconnector = db.db
+
+        self.set_db_values(dbconnector, "BFD_SESSION_TABLE|default|default|10.0.1.1",
+                        {"state": "DOWN", "type": "async_active", "local_addr" : "10.0.0.1",
+                        "tx_interval" :"300", "rx_interval" : "500", "multiplier" : "3", "multihop": "true"})
+        self.set_db_values(dbconnector, "BFD_SESSION_TABLE|default|Ethernet12|10.0.2.1",
+                        {"state": "UP", "type": "async_active", "local_addr" : "10.0.0.1",
+                        "tx_interval" :"200", "rx_interval" : "600", "multiplier" : "3", "multihop": "false"})
+        self.set_db_values(dbconnector, "BFD_SESSION_TABLE|default|default|2000::10:1",
+                        {"state": "UP", "type": "async_active", "local_addr" : "2000::1",
+                        "tx_interval" :"100", "rx_interval" : "700", "multiplier" : "3", "multihop": "false"})
+        self.set_db_values(dbconnector, "BFD_SESSION_TABLE|VrfRed|default|10.0.1.1",
+                        {"state": "UP", "type": "async_active", "local_addr" : "10.0.0.1",
+                        "tx_interval" :"400", "rx_interval" : "500", "multiplier" : "5", "multihop": "false"})
+
+        expected_output = """\
+Total number of BFD sessions: 4
+Peer Addr    Interface    Vrf      State    Type          Local Addr      TX Interval    RX Interval    Multiplier  Multihop
+-----------  -----------  -------  -------  ------------  ------------  -------------  -------------  ------------  ----------
+10.0.1.1     default      default  DOWN     async_active  10.0.0.1                300            500             3  true
+10.0.2.1     Ethernet12   default  UP       async_active  10.0.0.1                200            600             3  false
+2000::10:1   default      default  UP       async_active  2000::1                 100            700             3  false
+10.0.1.1     default      VrfRed   UP       async_active  10.0.0.1                400            500             5  false
+"""
+
+        result = runner.invoke(show.cli.commands['bfd'].commands['summary'], [], obj=db)
+        assert result.exit_code == 0
+        assert result.output == expected_output
+
+        expected_output = """\
+Total number of BFD sessions for peer IP 10.0.1.1: 2
+Peer Addr    Interface    Vrf      State    Type          Local Addr      TX Interval    RX Interval    Multiplier  Multihop
+-----------  -----------  -------  -------  ------------  ------------  -------------  -------------  ------------  ----------
+10.0.1.1     default      default  DOWN     async_active  10.0.0.1                300            500             3  true
+10.0.1.1     default      VrfRed   UP       async_active  10.0.0.1                400            500             5  false
+"""
+
+        result = runner.invoke(show.cli.commands['bfd'].commands['peer'], ['10.0.1.1'], obj=db)
+        assert result.exit_code == 0
+        assert result.output == expected_output
+
+        expected_output = """\
+Total number of BFD sessions for peer IP 10.0.2.1: 1
+Peer Addr    Interface    Vrf      State    Type          Local Addr      TX Interval    RX Interval    Multiplier  Multihop
+-----------  -----------  -------  -------  ------------  ------------  -------------  -------------  ------------  ----------
+10.0.2.1     Ethernet12   default  UP       async_active  10.0.0.1                200            600             3  false
+"""
+
+        result = runner.invoke(show.cli.commands['bfd'].commands['peer'], ['10.0.2.1'], obj=db)
+        assert result.exit_code == 0
+        assert result.output == expected_output
+
+        expected_output = """\
+No BFD sessions found for peer IP 10.0.3.1
+"""
+
+        result = runner.invoke(show.cli.commands['bfd'].commands['peer'], ['10.0.3.1'], obj=db)
+        assert result.exit_code == 0
+        assert result.output == expected_output
+
+
+    def test_bfd_show_no_session(self):
+        runner = CliRunner()
+        db = Db()
+
+        expected_output = """\
+Total number of BFD sessions: 0
+Peer Addr    Interface    Vrf    State    Type    Local Addr    TX Interval    RX Interval    Multiplier    Multihop
+-----------  -----------  -----  -------  ------  ------------  -------------  -------------  ------------  ----------
+"""
+
+        result = runner.invoke(show.cli.commands['bfd'].commands['summary'], [], obj=db)
+        assert result.exit_code == 0
+        assert result.output == expected_output