[yang]Fixing sonic-cfg-help to handle nested container (sonic-net#17260)

Why I did it
Fixing sonic-cfg-help to handle nested container scenario. In case of nested container, the inner container name acts as key for the table. For e.g.

"AUTO_TECHSUPPORT": {
        "GLOBAL": {
         }
}
Previous output

AUTO_TECHSUPPORT
Description: AUTO_TECHSUPPORT part of config_db.json

+-------------------------+----------------------------------------------------+-------------+-----------+-------------+
| Field                   | Description                                        | Mandatory   | Default   | Reference   |
+=========================+====================================================+=============+===========+=============+
| state                   | Knob to make techsupport invocation event-driven   |             |           |             |
|                         | based on core-dump generation                      |             |           |             |
+-------------------------+----------------------------------------------------+-------------+-----------+-------------+
| rate_limit_interval     | Minimum time in seconds between two successive     |             |           |             |
|                         | techsupport invocations. Configure 0 to explicitly |             |           |             |
|                         | disable                                            |             |           |             |
+-------------------------+----------------------------------------------------+-------------+-----------+-------------+
| max_techsupport_limit   | Max Limit in percentage for the cummulative size   |             |           |             |
|                         | of ts dumps. No cleanup is performed if the value  |             |           |             |
|                         | isn't configured or is 0.0                         |             |           |             |
+-------------------------+----------------------------------------------------+-------------+-----------+-------------+
| max_core_limit          | Max Limit in percentage for the cummulative size   |             |           |             |
|                         | of core dumps. No cleanup is performed if the      |             |           |             |
|                         | value isn't congiured or is 0.0                    |             |           |             |
+-------------------------+----------------------------------------------------+-------------+-----------+-------------+
| available_mem_threshold | Memory threshold; 0 to disable techsupport         |             | 10.0      |             |
|                         | invocation on memory usage threshold crossing      |             |           |             |
+-------------------------+----------------------------------------------------+-------------+-----------+-------------+
| min_available_mem       | Minimum Free memory (in MB) that should be         |             | 200       |             |
|                         | available for the techsupport execution to start   |             |           |             |
+-------------------------+----------------------------------------------------+-------------+-----------+-------------+
| since                   | Only collect the logs & core-dumps generated since |             |           |             |
|                         | the time provided. A default value of '2 days ago' |             |           |             |
|                         | is used if this value is not set explicitly or a   |             |           |             |
|                         | non-valid string is provided                       |             |           |             |
+-------------------------+----------------------------------------------------+-------------+-----------+-------------+


New output

AUTO_TECHSUPPORT
Description: AUTO_TECHSUPPORT part of config_db.json

key - GLOBAL
+-------------------------+----------------------------------------------------+-------------+-----------+-------------+
| Field                   | Description                                        | Mandatory   | Default   | Reference   |
+=========================+====================================================+=============+===========+=============+
| state                   | Knob to make techsupport invocation event-driven   |             |           |             |
|                         | based on core-dump generation                      |             |           |             |
+-------------------------+----------------------------------------------------+-------------+-----------+-------------+
| rate_limit_interval     | Minimum time in seconds between two successive     |             |           |             |
|                         | techsupport invocations. Configure 0 to explicitly |             |           |             |
|                         | disable                                            |             |           |             |
+-------------------------+----------------------------------------------------+-------------+-----------+-------------+
| max_techsupport_limit   | Max Limit in percentage for the cummulative size   |             |           |             |
|                         | of ts dumps. No cleanup is performed if the value  |             |           |             |
|                         | isn't configured or is 0.0                         |             |           |             |
+-------------------------+----------------------------------------------------+-------------+-----------+-------------+
| max_core_limit          | Max Limit in percentage for the cummulative size   |             |           |             |
|                         | of core dumps. No cleanup is performed if the      |             |           |             |
|                         | value isn't congiured or is 0.0                    |             |           |             |
+-------------------------+----------------------------------------------------+-------------+-----------+-------------+
| available_mem_threshold | Memory threshold; 0 to disable techsupport         |             | 10.0      |             |
|                         | invocation on memory usage threshold crossing      |             |           |             |
+-------------------------+----------------------------------------------------+-------------+-----------+-------------+
| min_available_mem       | Minimum Free memory (in MB) that should be         |             | 200       |             |
|                         | available for the techsupport execution to start   |             |           |             |
+-------------------------+----------------------------------------------------+-------------+-----------+-------------+
| since                   | Only collect the logs & core-dumps generated since |             |           |             |
|                         | the time provided. A default value of '2 days ago' |             |           |             |
|                         | is used if this value is not set explicitly or a   |             |           |             |
|                         | non-valid string is provided                       |             |           |             |
+-------------------------+----------------------------------------------------+-------------+-----------+-------------+


Work item tracking
Microsoft ADO (number only):
How I did it
Fixing sonic-cfg-help tool to handle nested container

How to verify it
Added UT to verify it.

src/sonic-yang-mgmt/sonic-cfg-help

@@ -54,7 +54,14 @@ class SonicCfgDescriber:
                 self.print_field_desc(table['list'], field)
                 print()
         elif table.get('container') is not None:
-            self.print_field_desc(table.get('container'), field)
+            if isinstance(table['container'], dict):
+                print("key - " + table['container'].get('@name'))
+                self.print_field_desc(table.get('container'), field)
+            elif isinstance(table['container'], list):
+                for c in table['container']:
+                    print("key - " + c.get('@name'))
+                    self.print_field_desc(c, field)
+
             print()
 
     def get_referenced_table_field(self, ref):

src/sonic-yang-mgmt/tests/test_cfghelp.py

@@ -19,6 +19,7 @@
 AUTO_TECHSUPPORT
 Description: AUTO_TECHSUPPORT part of config_db.json
 
+key - GLOBAL
 +-------------------------+----------------------------------------------------+-------------+-----------+-------------+
 | Field                   | Description                                        | Mandatory   | Default   | Reference   |
 +=========================+====================================================+=============+===========+=============+
@@ -56,6 +57,7 @@
 AUTO_TECHSUPPORT
 Description: AUTO_TECHSUPPORT part of config_db.json
 
+key - GLOBAL
 +---------+--------------------------------------------------+-------------+-----------+-------------+
 | Field   | Description                                      | Mandatory   | Default   | Reference   |
 +=========+==================================================+=============+===========+=============+
@@ -112,6 +114,25 @@
 
 """
 
+snmp_table_output="""\
+
+SNMP
+
+key - CONTACT
++---------+----------------------+-------------+-----------+-------------+
+| Field   | Description          | Mandatory   | Default   | Reference   |
++=========+======================+=============+===========+=============+
+| Contact | SNMP System Contact. |             |           |             |
++---------+----------------------+-------------+-----------+-------------+
+key - LOCATION
++----------+-----------------------+-------------+-----------+-------------+
+| Field    | Description           | Mandatory   | Default   | Reference   |
++==========+=======================+=============+===========+=============+
+| Location | SNMP System Location. |             |           |             |
++----------+-----------------------+-------------+-----------+-------------+
+
+"""
+
 class TestCfgHelp(TestCase):
 
     def setUp(self):
@@ -161,3 +182,8 @@ def test_when_condition(self):
         argument = ['-t', 'ACL_RULE', '-f', 'ICMP_TYPE']
         output = self.run_script(argument)
         self.assertEqual(output, acl_rule_table_field_output)
+
+    def test_nested_container(self):
+        argument = ['-t', 'SNMP']
+        output = self.run_script(argument)
+        self.assertEqual(output, snmp_table_output)