[GCU] Supressing YANG errors from libyang while sorting (sonic-net#1991)

#### What I did

Fixes sonic-net#2025

Stopping SonicYang from printing errors during config validation or moves generation.

If callers uses the `-v` option, they will see the SonicYang logs printed.

Also made sure that SonicYang returned error are properly propagated, so the user can see the exact errors.

#### How I did it
Used the the option `print_log_enabled` while creating `SonicYang`
```python
sy = sonic_yang.SonicYang(self.yang_dir, print_log_enabled=sonic_yang_print_log_enabled)
```
#### How to verify it
Manually tested the change to the output, and added unit-tests to the gu_common functions that were modified.

#### Previous command output (if the output of a command-line utility has changed)
Given an invalid patch will remove PORT table, while the PORT table is used.

```
admin@vlab-01:~$ sudo config apply-patch remove_port.json-patch -i /FEATURE
Patch Applier: Patch application starting.
Patch Applier: Patch: [{"op": "remove", "path": "/PORT"}]
Patch Applier: Getting current config db.
Patch Applier: Simulating the target full config after applying the patch.
Patch Applier: Validating target config does not have empty tables, since they do not show up in ConfigDb.
Patch Applier: Sorting patch updates.
sonic_yang(6):Note: Below table(s) have no YANG models: CONSOLE_SWITCH, DEVICE_NEIGHBOR_METADATA, DHCP_SERVER, KDUMP, RESTAPI, SNMP, SNMP_COMMUNITY, TELEMETRY
libyang[0]: Leafref "/sonic-port:sonic-port/sonic-port:PORT/sonic-port:PORT_LIST/sonic-port:name" of value "Ethernet112" points to a non-existing leaf. (path: /sonic-buffer-pg:sonic-buffer-pg/BUFFER_PG/BUFFER_PG_LIST[port='Ethernet112'][pg_num='0']/port)
libyang[0]: Leafref "/sonic-port:sonic-port/sonic-port:PORT/sonic-port:PORT_LIST/sonic-port:name" of value "Ethernet112" points to a non-existing leaf. (path: /sonic-buffer-pg:sonic-buffer-pg/BUFFER_PG/BUFFER_PG_LIST[port='Ethernet112'][pg_num='3-4']/port)
libyang[0]: Leafref "/sonic-port:sonic-port/sonic-port:PORT/sonic-port:PORT_LIST/sonic-port:name" of value "Ethernet116" points to a non-existing leaf. (path: /sonic-buffer-pg:sonic-buffer-pg/BUFFER_PG/BUFFER_PG_LIST[port='Ethernet116'][pg_num='0']/port)
>>>> 10s of log lines
libyang[0]: Leafref "/sonic-port:sonic-port/sonic-port:PORT/sonic-port:PORT_LIST/sonic-port:name" of value "Ethernet96" points to a non-existing leaf. (path: /sonic-port-qos-map:sonic-port-qos-map/PORT_QOS_MAP/PORT_QOS_MAP_LIST[ifname='Ethernet96']/ifname)
sonic_yang(3):Data Loading Failed:Leafref "/sonic-port:sonic-port/sonic-port:PORT/sonic-port:PORT_LIST/sonic-port:name" of value "Ethernet96" points to a non-existing leaf.
Failed to apply patch
Usage: config apply-patch [OPTIONS] PATCH_FILE_PATH
Try "config apply-patch -h" for help.

Error: Given patch is not valid because it will result in an invalid config
admin@vlab-01:~$ 
```
#### New command output (if the output of a command-line utility has changed)
```
admin@vlab-01:~$ sudo config apply-patch remove_port.json-patch -i /FEATURE
Patch Applier: Patch application starting.
Patch Applier: Patch: [{"op": "remove", "path": "/PORT"}]
Patch Applier: Getting current config db.
Patch Applier: Simulating the target full config after applying the patch.
Patch Applier: Validating target config does not have empty tables, since they do not show up in ConfigDb.
Patch Applier: Sorting patch updates.
Failed to apply patch
Usage: config apply-patch [OPTIONS] PATCH_FILE_PATH
Try "config apply-patch -h" for help.

Error: Given patch will produce invalid config. Error: Data Loading Failed
Leafref "/sonic-port:sonic-port/sonic-port:PORT/sonic-port:PORT_LIST/sonic-port:name" of value "Ethernet96" points to a non-existing leaf.
admin@vlab-01:~$ 
```

generic_config_updater/gu_common.py

@@ -105,9 +105,9 @@ def validate_sonic_yang_config(self, sonic_yang_as_json):
             sy.loadData(config_db_as_json)
 
             sy.validate_data_tree()
-            return True
+            return True, None
         except sonic_yang.SonicYangException as ex:
-            return False
+            return False, ex
 
     def validate_config_db_config(self, config_db_as_json):
         sy = self.create_sonic_yang_with_loaded_models()
@@ -118,9 +118,9 @@ def validate_config_db_config(self, config_db_as_json):
             sy.loadData(tmp_config_db_as_json)
 
             sy.validate_data_tree()
-            return True
+            return True, None
         except sonic_yang.SonicYangException as ex:
-            return False
+            return False, ex
 
     def crop_tables_without_yang(self, config_db_as_json):
         sy = self.create_sonic_yang_with_loaded_models()
@@ -151,7 +151,8 @@ def remove_empty_tables(self, config):
     def create_sonic_yang_with_loaded_models(self):
         # sonic_yang_with_loaded_models will only be initialized once the first time this method is called
         if self.sonic_yang_with_loaded_models is None:
-            loaded_models_sy = sonic_yang.SonicYang(self.yang_dir)
+            sonic_yang_print_log_enabled = genericUpdaterLogging.get_verbose()
+            loaded_models_sy = sonic_yang.SonicYang(self.yang_dir, print_log_enabled=sonic_yang_print_log_enabled)
             loaded_models_sy.loadYangModel() # This call takes a long time (100s of ms) because it reads files from disk
             self.sonic_yang_with_loaded_models = loaded_models_sy
 
@@ -829,6 +830,9 @@ def __init__(self):
     def set_verbose(self, verbose):
         self._verbose = verbose
 
+    def get_verbose(self):
+        return self._verbose
+
     def get_logger(self, title, print_all_to_console=False):
         return TitledLogger(SYSLOG_IDENTIFIER, title, self._verbose, print_all_to_console)
 

generic_config_updater/patch_sorter.py

@@ -562,7 +562,8 @@ def __init__(self, config_wrapper):
 
     def validate(self, move, diff):
         simulated_config = move.apply(diff.current_config)
-        return self.config_wrapper.validate_config_db_config(simulated_config)
+        is_valid, error = self.config_wrapper.validate_config_db_config(simulated_config)
+        return is_valid
 
 # TODO: Add this validation to YANG models instead
 class UniqueLanesMoveValidator:
@@ -1543,8 +1544,9 @@ def sort(self, patch, algorithm=Algorithm.DFS):
 
         # Validate target config
         self.logger.log_info("Validating target config according to YANG models.")
-        if not(self.config_wrapper.validate_config_db_config(target_config)):
-            raise ValueError(f"Given patch is not valid because it will result in an invalid config")
+        is_valid, error = self.config_wrapper.validate_config_db_config(target_config)
+        if not is_valid:
+            raise ValueError(f"Given patch will produce invalid config. Error: {error}")
 
         # Generate list of changes to apply
         self.logger.log_info("Sorting patch updates.")
@@ -1731,8 +1733,9 @@ def sort(self, patch, algorithm=Algorithm.DFS):
 
         # Validate YANG covered target config
         self.logger.log_info("Validating YANG covered target config according to YANG models.")
-        if not(self.config_wrapper.validate_config_db_config(target_config_yang)):
-            raise ValueError(f"Given patch is not valid because it will result in an invalid config")
+        is_valid, error = self.config_wrapper.validate_config_db_config(target_config_yang)
+        if not is_valid:
+            raise ValueError(f"Given patch will produce invalid config. Error: {error}")
 
         # Generating changes associated with non-YANG covered configs
         self.logger.log_info("Sorting non-YANG covered configs patch updates.")

tests/generic_config_updater/gu_common_test.py

@@ -144,43 +144,47 @@ def test_validate_sonic_yang_config__valid_config__returns_true(self):
         expected = True
 
         # Act
-        actual = config_wrapper.validate_sonic_yang_config(Files.SONIC_YANG_AS_JSON)
+        actual, error = config_wrapper.validate_sonic_yang_config(Files.SONIC_YANG_AS_JSON)
 
         # Assert
         self.assertEqual(expected, actual)
+        self.assertIsNone(error)
 
     def test_validate_sonic_yang_config__invvalid_config__returns_false(self):
         # Arrange
         config_wrapper = gu_common.ConfigWrapper()
         expected = False
 
         # Act
-        actual = config_wrapper.validate_sonic_yang_config(Files.SONIC_YANG_AS_JSON_INVALID)
+        actual, error = config_wrapper.validate_sonic_yang_config(Files.SONIC_YANG_AS_JSON_INVALID)
 
         # Assert
         self.assertEqual(expected, actual)
+        self.assertIsNotNone(error)
 
     def test_validate_config_db_config__valid_config__returns_true(self):
         # Arrange
         config_wrapper = gu_common.ConfigWrapper()
         expected = True
 
         # Act
-        actual = config_wrapper.validate_config_db_config(Files.CONFIG_DB_AS_JSON)
+        actual, error = config_wrapper.validate_config_db_config(Files.CONFIG_DB_AS_JSON)
 
         # Assert
         self.assertEqual(expected, actual)
+        self.assertIsNone(error)
 
     def test_validate_config_db_config__invalid_config__returns_false(self):
         # Arrange
         config_wrapper = gu_common.ConfigWrapper()
         expected = False
 
         # Act
-        actual = config_wrapper.validate_config_db_config(Files.CONFIG_DB_AS_JSON_INVALID)
+        actual, error = config_wrapper.validate_config_db_config(Files.CONFIG_DB_AS_JSON_INVALID)
 
         # Assert
         self.assertEqual(expected, actual)
+        self.assertIsNotNone(error)
 
     def test_crop_tables_without_yang__returns_cropped_config_db_as_json(self):
         # Arrange

tests/generic_config_updater/patch_sorter_test.py

@@ -925,7 +925,7 @@ def test_validate__invalid_config_db_after_applying_move__failure(self):
         # Arrange
         config_wrapper = Mock()
         config_wrapper.validate_config_db_config.side_effect = \
-            create_side_effect_dict({(str(self.any_simulated_config),): False})
+            create_side_effect_dict({(str(self.any_simulated_config),): (False, None)})
         validator = ps.FullConfigMoveValidator(config_wrapper)
 
         # Act and assert
@@ -935,7 +935,7 @@ def test_validate__valid_config_db_after_applying_move__success(self):
         # Arrange
         config_wrapper = Mock()
         config_wrapper.validate_config_db_config.side_effect = \
-            create_side_effect_dict({(str(self.any_simulated_config),): True})
+            create_side_effect_dict({(str(self.any_simulated_config),): (True, None)})
         validator = ps.FullConfigMoveValidator(config_wrapper)
 
         # Act and assert
@@ -3100,7 +3100,8 @@ def run_single_success_case(self, data, skip_exact_change_list_match):
         simulated_config = current_config
         for change in actual_changes:
             simulated_config = change.apply(simulated_config)
-            self.assertTrue(self.config_wrapper.validate_config_db_config(simulated_config))
+            is_valid, error = self.config_wrapper.validate_config_db_config(simulated_config)
+            self.assertTrue(is_valid, f"Change will produce invalid config. Error: {error}")
         self.assertEqual(target_config, simulated_config)
 
     def test_patch_sorter_failure(self):
@@ -3424,7 +3425,7 @@ def __create_patch_sorter(self,
                  (str(any_target_config),): (any_target_config_yang, any_target_config_non_yang)})
 
         config_wrapper.validate_config_db_config.side_effect = \
-            create_side_effect_dict({(str(any_target_config_yang),): valid_yang_covered_config})
+            create_side_effect_dict({(str(any_target_config_yang),): (valid_yang_covered_config, None)})
 
         patch_wrapper.generate_patch.side_effect = \
             create_side_effect_dict(
@@ -3517,7 +3518,7 @@ def __create_patch_sorter(self,
 
         config_wrapper.validate_config_db_config.side_effect = \
             create_side_effect_dict(
-                {(str(any_target_config),): valid_config_db})
+                {(str(any_target_config),): (valid_config_db, None)})
 
 
         inner_patch_sorter.sort.side_effect = \