[show] Fix warnings, related to gearbox, while show commands execution (sonic-net#1343)

* Performing getting from APPL_DB of all the keys while checking readiness
  status of the gearbox to prevent warnings sending to syslog if there no
  records of PHYs of a gearbox in APPL_DB.
* Moving of the gearbox readiness status checking procedure to separated
  function.

Signed-off-by: Maksym Belei <Maksym_Belei@jabil.com>

Author: maksymbelei95

show/main.py

@@ -2,6 +2,7 @@
 import os
 import subprocess
 import sys
+import re
 
 import click
 import netifaces
@@ -45,6 +46,8 @@
 
 VLAN_SUB_INTERFACE_SEPARATOR = '.'
 
+GEARBOX_TABLE_PHY_PATTERN = r"_GEARBOX_TABLE:phy:*"
+
 # To be enhanced. Routing-stack information should be collected from a global
 # location (configdb?), so that we prevent the continous execution of this
 # bash oneliner. To be revisited once routing-stack info is tracked somewhere.
@@ -119,7 +122,20 @@ def connect_config_db():
     config_db.connect()
     return config_db
 
+def is_gearbox_configured():
+    """
+    Checks whether Gearbox is configured or not
+    """
+    app_db = SonicV2Connector()
+    app_db.connect(app_db.APPL_DB)
 
+    keys = app_db.keys(app_db.APPL_DB, '*')
+
+    # If any _GEARBOX_TABLE:phy:* records present in APPL_DB, then the gearbox is configured
+    if any(re.match(GEARBOX_TABLE_PHY_PATTERN, key) for key in keys):
+        return True
+    else:
+        return False
 
 CONTEXT_SETTINGS = dict(help_option_names=['-h', '--help', '-?'])
 
@@ -160,10 +176,7 @@ def cli(ctx):
 cli.add_command(warm_restart.warm_restart)
 
 # Add greabox commands only if GEARBOX is configured
-# TODO: Find a cleaner way to do this
-app_db = SonicV2Connector(host='127.0.0.1')
-app_db.connect(app_db.APPL_DB)
-if app_db.keys(app_db.APPL_DB, '_GEARBOX_TABLE:phy:*'):
+if is_gearbox_configured():
     cli.add_command(gearbox.gearbox)