generic_updater: Fix service validator related issues (sonic-net#1901)

1) Copy generic_updater_config.conf.json as part of install
2) Read conf file from install dir
3) Drop empty keys & tables upon jsonpatch.JsonPatch.apply to be in sync with
   redis update
4) Prefix service_validator module path with "generic_updater"

Author: renukamanavalan

generic_config_updater/change_applier.py

@@ -8,8 +8,8 @@
 from swsscommon.swsscommon import ConfigDBConnector
 from .gu_common import genericUpdaterLogging
 
-
-UPDATER_CONF_FILE = "/etc/sonic/generic_config_updater.conf"
+SCRIPT_DIR = os.path.dirname(os.path.realpath(__file__))
+UPDATER_CONF_FILE = f"{SCRIPT_DIR}/generic_updater_config.conf.json"
 logger = genericUpdaterLogging.get_logger(title="Change Applier")
 
 print_to_console = False
@@ -44,6 +44,19 @@ def set_config(config_db, tbl, key, data):
     config_db.set_entry(tbl, key, data)
 
 
+def prune_empty_table(data):
+    # For JSON Patch empty entries are valid
+    # With redis, when last key is removed, the table gets removed too.
+    #
+    # Hence where required, prune tables with no keys.
+    #
+    tables = list(data.keys())
+    for tbl in tables:
+        if not data[tbl]:
+            data.pop(tbl)
+    return data
+
+
 class ChangeApplier:
 
     updater_conf = None
@@ -111,7 +124,7 @@ def _report_mismatch(self, run_data, upd_data):
 
     def apply(self, change):
         run_data = self._get_running_config()
-        upd_data = change.apply(copy.deepcopy(run_data))
+        upd_data = prune_empty_table(change.apply(copy.deepcopy(run_data)))
         upd_keys = defaultdict(dict)
 
         for tbl in sorted(set(run_data.keys()).union(set(upd_data.keys()))):

generic_config_updater/generic_updater_config.conf.json

@@ -1,21 +1,4 @@
 {
-    "tables": {
-        "": {
-            "services_to_validate": [ "system_health" ]
-        },
-        "PORT": {
-            "services_to_validate": [ "port_service" ]
-        },
-        "SYSLOG_SERVER":{
-            "services_to_validate": [ "rsyslog" ]
-        },
-        "DHCP_RELAY": {
-            "services_to_validate": [ "dhcp-relay" ]
-        },
-        "DHCP_SERVER": {
-            "services_to_validate": [ "dhcp-relay" ]
-        }
-    },
     "README": [
         "Validate_commands provides, module & method name as ",
         "    <module name>.<method name>",
@@ -41,6 +24,23 @@
         "Note: The commands may be called in any order",
         ""
     ],
+    "tables": {
+        "": {
+            "services_to_validate": [ "system_health" ]
+        },
+        "PORT": {
+            "services_to_validate": [ "port_service" ]
+        },
+        "SYSLOG_SERVER":{
+            "services_to_validate": [ "rsyslog" ]
+        },
+        "DHCP_RELAY": {
+            "services_to_validate": [ "dhcp-relay" ]
+        },
+        "DHCP_SERVER": {
+            "services_to_validate": [ "dhcp-relay" ]
+        }
+    },
     "services": {
         "system_health": { 
             "validate_commands": [ ]
@@ -49,10 +49,10 @@
             "validate_commands": [ ]
         },
         "rsyslog": {
-            "validate_commands": [ "services_validator.ryslog_validator" ]
+            "validate_commands": [ "generic_config_updater.services_validator.ryslog_validator" ]
         },
         "dhcp-relay": {
-            "validate_commands": [ "services_validator.dhcp_validator" ]
+            "validate_commands": [ "generic_config_updater.services_validator.dhcp_validator" ]
         }
     }
 }

setup.py

@@ -58,6 +58,7 @@
         'watchdogutil',
     ],
     package_data={
+        'generic_config_updater': ['generic_updater_config.conf.json'],
         'show': ['aliases.ini'],
         'sonic_installer': ['aliases.ini'],
         'tests': ['acl_input/*',