[Functional] initialize without ports on config_db.json - swss (portsyncd) failure

[NoySa]

Description

try to init with 0 ports on config_db.json leads to swss docker down (portsyncd failure)

manual testing. always reproduced. no degradation.

Steps to reproduce the issue:

1. Remove all ports from /etc/sonic/config_db.json from the PORT section
2. make sure no ports related configuration
3. reboot

Describe the results you received:

swss fails (portsyncd fails)

Warning appears on sonic shell after show commands (for example "show interfaces status"):
Warning: failed to retrieve PORT table from ConfigDB!

Errors on syslog:
Mar 30 11:52:53.936664 r-tigris-22 ERR swss#portsyncd: :- main: ConfigDB does not have port information, exiting...

Mar 30 12:51:43.874964 r-tigris-22 ERR snmp#snmp-subagent [ax_interface] ERROR: MIBUpdater.start() caught an unexpected exception during update_data()#012Traceback (most recent call last):#12 File "/usr/local/lib/python3.7/dist-packages/ax_interface/mib.py", line 37, in start#012 self.reinit_data()#12 File "/usr/local/lib/python3.7/dist-packages/sonic_ax_impl/mibs/ieee802_1ab.py", line 570, in reinit_data#012 _, _, _, self.oid_name_map = Namespace.get_sync_d_from_all_namespace(mibs.init_sync_d_interface_tables, self.db_conn)#12 File "/usr/local/lib/python3.7/dist-packages/sonic_ax_impl/mibs/init.py", line 563, in get_sync_d_from_all_namespace#012 ns_tuple = per_namespace_func(db_conn)#12 File "/usr/local/lib/python3.7/dist-packages/sonic_ax_impl/mibs/init.py", line 244, in init_sync_d_interface_tables#012 if_name_map_util, if_id_map_util = port_util.get_interface_oid_map(db_conn)#12 File "/usr/local/lib/python3.7/dist-packages/swsssdk/port_util.py", line 65, in get_interface_oid_map#012 if_name_map = db.get_all('COUNTERS_DB', 'COUNTERS_PORT_NAME_MAP', blocking=True)#12 File "/usr/lib/python3/dist-packages/swsscommon/swsscommon.py", line 1588, in get_all#012 return dict(super(SonicV2Connector, self).get_all(db_name, _hash, blocking))#12 File "/usr/lib/python3/dist-packages/swsscommon/swsscommon.py", line 1545, in get_all#012 return _swsscommon.SonicV2Connector_Native_get_all(self, db_name, _hash, blocking)#012RuntimeError: Key '{COUNTERS_PORT_NAME_MAP}' unavailable in database '{COUNTERS_DB}'

Describe the results you expected:

no errors. swss docker is stable

Output of show version:

SONiC Software Version: SONiC.SONIC.202012.52-50e4cc15_Internal
Distribution: Debian 10.8
Kernel: 4.19.0-12-2-amd64
Build commit: 50e4cc1
Build date: Tue Mar 23 10:25:18 UTC 2021
Built by: sw-r2d2-bot@r-build-sonic-ci03

Platform: x86_64-mlnx_msn3800-r0
HwSKU: ACS-MSN3800
ASIC: mellanox
ASIC Count: 1
Serial Number: MT1937X00537
Uptime: 13:07:08 up 54 min, 1 user, load average: 1.25, 1.58, 1.60

Docker images:
REPOSITORY TAG IMAGE ID SIZE
docker-teamd SONIC.202012.52-50e4cc15_Internal e404a957f154 412MB
docker-teamd latest e404a957f154 412MB
docker-nat SONIC.202012.52-50e4cc15_Internal 060b170d465d 415MB
docker-nat latest 060b170d465d 415MB
docker-platform-monitor SONIC.202012.52-50e4cc15_Internal 866984132b08 693MB
docker-platform-monitor latest 866984132b08 693MB
docker-orchagent SONIC.202012.52-50e4cc15_Internal 2da47edc09a5 431MB
docker-orchagent latest 2da47edc09a5 431MB
docker-fpm-frr SONIC.202012.52-50e4cc15_Internal 12a1712803da 431MB
docker-fpm-frr latest 12a1712803da 431MB
docker-sflow SONIC.202012.52-50e4cc15_Internal 6205a14bb9df 413MB
docker-sflow latest 6205a14bb9df 413MB
docker-syncd-mlnx SONIC.202012.52-50e4cc15_Internal f5386fd640ba 666MB
docker-syncd-mlnx latest f5386fd640ba 666MB
docker-dhcp-relay SONIC.202012.52-50e4cc15_Internal cb5a7323aeb9 409MB
docker-dhcp-relay latest cb5a7323aeb9 409MB
docker-snmp SONIC.202012.52-50e4cc15_Internal 8df6c0d14af7 438MB
docker-snmp latest 8df6c0d14af7 438MB
docker-sonic-mgmt-framework SONIC.202012.52-50e4cc15_Internal 4881ef3e8dc7 616MB
docker-sonic-mgmt-framework latest 4881ef3e8dc7 616MB
docker-router-advertiser SONIC.202012.52-50e4cc15_Internal 7e59764069ca 398MB
docker-router-advertiser latest 7e59764069ca 398MB
docker-lldp SONIC.202012.52-50e4cc15_Internal 33da46fe8a7f 438MB
docker-lldp latest 33da46fe8a7f 438MB
docker-database SONIC.202012.52-50e4cc15_Internal e65ccc177592 398MB
docker-database latest e65ccc177592 398MB
docker-sonic-telemetry SONIC.202012.52-50e4cc15_Internal 5e079afb02ab 487MB
docker-sonic-telemetry latest 5e079afb02ab 487MB

Additional information you deem important (e.g. issue happens only occasionally):

[NoySa]

files.zip

[anshuv-mfst]

@dprital - could you please look into the issue, thanks.

[liorghub]

@anshuv-mfst
@NoySa
@dprital

The fix is merged, see sonic-net/sonic-swss#1808.
Please close this bug.