[show]: Add show policer command (sonic-net#540)

root@sonic:# show policer
Name    Type     Mode      CIR    CBS
------  -------  ------  -----  -----
test    packets  sr_tcm    100    100

Signed-off-by: Shu0T1an ChenG <shuche@microsoft.com>

acl_loader/main.py

@@ -49,6 +49,7 @@ class AclLoader(object):
     ACL_TABLE_TYPE_MIRROR = "MIRROR"
     ACL_TABLE_TYPE_CTRLPLANE = "CTRLPLANE"
     MIRROR_SESSION = "MIRROR_SESSION"
+    POLICER = "POLICER"
     SESSION_PREFIX = "everflow"
 
     min_priority = 1
@@ -92,10 +93,11 @@ def __init__(self):
         self.read_tables_info()
         self.read_rules_info()
         self.read_sessions_info()
+        self.read_policers_info()
 
     def read_tables_info(self):
         """
-        Read ACL tables information from Config DB
+        Read ACL_TABLE table from configuration database
         :return:
         """
         self.tables_db_info = self.configdb.get_table(self.ACL_TABLE)
@@ -105,17 +107,27 @@ def get_tables_db_info(self):
 
     def read_rules_info(self):
         """
-        Read rules information from Config DB
+        Read ACL_RULE table from configuration database
         :return:
         """
         self.rules_db_info = self.configdb.get_table(self.ACL_RULE)
 
     def get_rules_db_info(self):
         return self.rules_db_info
 
+    def read_policers_info(self):
+        """
+        Read POLICER table from configuration database
+        :return:
+        """
+        self.policers_db_info = self.configdb.get_table(self.POLICER)
+
+    def get_policers_db_info(self):
+        return self.policers_db_info
+
     def read_sessions_info(self):
         """
-        Read ACL tables information from Config DB
+        Read MIRROR_SESSION table from configuration database
         :return:
         """
         self.sessions_db_info = self.configdb.get_table(self.MIRROR_SESSION)
@@ -128,15 +140,11 @@ def read_sessions_info(self):
             self.sessions_db_info[key]["status"] = status
 
     def get_sessions_db_info(self):
-        """
-        Read mirror session information from Config DB
-        :return:
-        """
         return self.sessions_db_info
 
     def get_session_name(self):
         """
-        Read mirror session name from Config DB
+        Get requested mirror session name or default session
         :return: Mirror session name
         """
         if self.requested_session:
@@ -545,6 +553,25 @@ def show_session(self, session_name):
 
         print(tabulate.tabulate(data, headers=header, tablefmt="simple", missingval=""))
 
+
+    def show_policer(self, policer_name):
+        """
+        Show policer configuration.
+        :param policer_name: Optional. Policer name. Filter policers by specified name.
+        :return:
+        """
+        header = ("Name", "Type", "Mode", "CIR", "CBS")
+
+        data = []
+        for key, val in self.get_policers_db_info().iteritems():
+            if policer_name and key != policer_name:
+                continue
+
+            data.append([key, val["meter_type"], val["mode"], val.get("cir", ""), val.get("cbs", "")])
+
+        print(tabulate.tabulate(data, headers=header, tablefmt="simple", missingval=""))
+
+
     def show_rule(self, table_name, rule_id):
         """
         Show ACL rules configuration.
@@ -648,6 +675,18 @@ def session(ctx, session_name):
     acl_loader.show_session(session_name)
 
 
+@show.command()
+@click.argument('policer_name', type=click.STRING, required=False)
+@click.pass_context
+def policer(ctx, policer_name):
+    """
+    Show policer configuration.
+    :return:
+    """
+    acl_loader = ctx.obj["acl_loader"]
+    acl_loader.show_policer(policer_name)
+
+
 @show.command()
 @click.argument('table_name', type=click.STRING, required=False)
 @click.argument('rule_id', type=click.STRING, required=False)

show/main.py

@@ -1640,6 +1640,22 @@ def mirror_session(session_name, verbose):
     run_command(cmd, display_cmd=verbose)
 
 
+#
+# 'policer' command  ("show policer ...")
+#
+@cli.command()
+@click.argument('policer_name', required=False)
+@click.option('--verbose', is_flag=True, help="Enable verbose output")
+def policer(policer_name, verbose):
+    """Show existing policers"""
+    cmd = "acl-loader show policer"
+
+    if policer_name is not None:
+        cmd += " {}".format(policer_name)
+
+    run_command(cmd, display_cmd=verbose)
+
+
 #
 # 'acl' group ###
 #