[route_check]: Ignore ASIC only SOC IPs (sonic-net#2548)

* [tests]: Improve route check test

- Split test into separate methods based on functionality being tested
- Parametrize main test method for better granularity when viewing results/running test cases
- Add config DB mocking support
- Move some setup/teardown code to fixtures for better consistency
- Extract test data to separate file
- Ignore routes for SOC IPs that are only present in the ASIC
- Add test case to cover ASIC only SOC IPs

Signed-off-by: Lawrence Lee <lawlee@microsoft.com>

Author: theasianpianist

scripts/route_check.py

@@ -450,13 +450,17 @@ def filter_out_vnet_routes(routes):
     return updated_routes
 
 
+def is_dualtor(config_db):
+    device_metadata = config_db.get_table('DEVICE_METADATA')
+    subtype = device_metadata['localhost'].get('subtype', '')
+    return subtype.lower() == 'dualtor'
+
+
 def filter_out_standalone_tunnel_routes(routes):
     config_db = swsscommon.ConfigDBConnector()
     config_db.connect()
-    device_metadata = config_db.get_table('DEVICE_METADATA')
-    subtype = device_metadata['localhost'].get('subtype', '')
 
-    if subtype.lower() != 'dualtor':
+    if not is_dualtor(config_db):
         return routes
 
     app_db = swsscommon.DBConnector('APPL_DB', 0)
@@ -489,6 +493,45 @@ def filter_out_standalone_tunnel_routes(routes):
     return updated_routes
 
 
+def get_soc_ips(config_db):
+    mux_table = config_db.get_table('MUX_CABLE')
+    soc_ips = []
+    for _, mux_entry in mux_table.items():
+        if mux_entry.get("cable_type", "") == "active-active" and "soc_ipv4" in mux_entry:
+            soc_ips.append(mux_entry["soc_ipv4"])
+
+    return soc_ips
+
+
+def filter_out_soc_ip_routes(routes):
+    """
+    Ignore ASIC only routes for SOC IPs
+
+    For active-active cables, we want the tunnel route for SOC IPs
+    to only be programmed to the ASIC and not to the kernel. This is to allow
+    gRPC connections coming from ycabled to always use the direct link (since this
+    will use the kernel routing table), but still provide connectivity to any external
+    traffic in case of a link issue (since this traffic will be forwarded by the ASIC).
+    """
+    config_db = swsscommon.ConfigDBConnector()
+    config_db.connect()
+
+    if not is_dualtor(config_db):
+        return routes
+
+    soc_ips = get_soc_ips(config_db)
+
+    if not soc_ips:
+        return routes
+    
+    updated_routes = []
+    for route in routes:
+        if route not in soc_ips:
+            updated_routes.append(route)
+
+    return updated_routes
+
+
 def check_routes():
     """
     The heart of this script which runs the checks.
@@ -526,6 +569,7 @@ def check_routes():
     rt_asic_miss = filter_out_default_routes(rt_asic_miss)
     rt_asic_miss = filter_out_vnet_routes(rt_asic_miss)
     rt_asic_miss = filter_out_standalone_tunnel_routes(rt_asic_miss)
+    rt_asic_miss = filter_out_soc_ip_routes(rt_asic_miss)
 
     # Check APPL-DB INTF_TABLE with ASIC table route entries
     intf_appl_miss, _ = diff_sorted_lists(intf_appl, rt_asic)

tests/mock_tables/config_db.json

@@ -831,8 +831,7 @@
         "mac": "1d:34:db:16:a6:00",
         "platform": "x86_64-mlnx_msn3800-r0",
         "peer_switch": "sonic-switch",
-        "type": "ToRRouter",
-        "subtype": "DualToR"
+        "type": "ToRRouter"
     },
     "SNMP_COMMUNITY|msft": {
         "TYPE": "RO"