Backing up database fails during warmboot

[vaibhavhd]

Description

Steps to reproduce the issue:

1. Run test test_warm_reboot OR manually issue warmboot
2. The test fails, as the warmboot flag was not set
3. In the CLI output, below errors are seen during backing up database:

Thu 18 Feb 2021 01:13:22 AM UTC Backing up database ...
An exception of type AttributeError occurred. Arguments:
("type object 'SonicDBConfig' has no attribute 'get_port'",)
Error: No such container:path: database:/var/lib//dump.rdb
rm: cannot remove '/var/lib//dump.rdb': No such file or directory

Describe the results you received:

admin@str-s6100-acs-4:~$ sudo warm-reboot -vvv
Thu 18 Feb 2021 01:12:55 AM UTC Saving counters folder before warmboot...
Thu 18 Feb 2021 01:12:58 AM UTC Pausing orchagent ...
Thu 18 Feb 2021 01:12:59 AM UTC Collecting logs to check ssd health before warm-reboot...
Thu 18 Feb 2021 01:12:59 AM UTC Stopping nat ...
Thu 18 Feb 2021 01:13:00 AM UTC Stopped nat ...
Thu 18 Feb 2021 01:13:00 AM UTC Stopping radv service...
Thu 18 Feb 2021 01:13:01 AM UTC Stopped radv service...
Thu 18 Feb 2021 01:13:01 AM UTC Stopping bgp ...
Thu 18 Feb 2021 01:13:07 AM UTC Stopped bgp ...
Thu 18 Feb 2021 01:13:07 AM UTC Stopping sflow ...
Thu 18 Feb 2021 01:13:07 AM UTC Stopped sflow ...
Thu 18 Feb 2021 01:13:10 AM UTC Stopping swss service ...
Thu 18 Feb 2021 01:13:21 AM UTC Stopped swss service ...
Thu 18 Feb 2021 01:13:21 AM UTC Initialize pre-shutdown ...
Thu 18 Feb 2021 01:13:21 AM UTC Requesting pre-shutdown ...
Thu 18 Feb 2021 01:13:22 AM UTC Waiting for pre-shutdown ...
Thu 18 Feb 2021 01:13:22 AM UTC Pre-shutdown succeeded ...
Thu 18 Feb 2021 01:13:22 AM UTC Backing up database ...
An exception of type AttributeError occurred. Arguments:
("type object 'SonicDBConfig' has no attribute 'get_port'",)
Error: No such container:path: database:/var/lib//dump.rdb
rm: cannot remove '/var/lib//dump.rdb': No such file or directory
Thu 18 Feb 2021 01:13:23 AM UTC Stopping teamd ...
Thu 18 Feb 2021 01:13:31 AM UTC Stopped teamd ...
Thu 18 Feb 2021 01:13:31 AM UTC Stopping syncd ...
Thu 18 Feb 2021 01:13:47 AM UTC Stopped syncd ...
Thu 18 Feb 2021 01:13:47 AM UTC Stopping all remaining containers ...
Warning: Stopping telemetry.service, but it can still be activated by:
  telemetry.timer
Warning: Stopping mgmt-framework.service, but it can still be activated by:
  mgmt-framework.timer
Thu 18 Feb 2021 01:13:55 AM UTC Stopped all remaining containers ...
Thu 18 Feb 2021 01:13:57 AM UTC updating ssd fw forwarm-reboot
Thu 18 Feb 2021 01:13:57 AM UTC Enabling Watchdog before warm-reboot
Watchdog armed for 180 seconds
Thu 18 Feb 2021 01:13:58 AM UTC Running x86_64-dell_s6100_c2538-r0 specific plugin...
Thu 18 Feb 2021 01:13:58 AM UTC Rebooting with /sbin/kexec -e to SONiC-OS-HEAD.399-7790a74d ...

Describe the results you expected:

Database backup should proceed without errors during warmboot.

Output of show version:

SONiC Software Version: SONiC.HEAD.395-f6bee730
Distribution: Debian 10.8
Kernel: 4.19.0-12-2-amd64
Build commit: f6bee730
Build date: Mon Feb 15 20:38:03 UTC 2021
Built by: johnar@jenkins-worker-22

Platform: x86_64-arista_7050cx3_32s
HwSKU: Arista-7050CX3-32S-C32
ASIC: broadcom

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