[system-health] When disabling a feature the SYSTEM_READY|SYSTEM_STAT…

[DavidZagury]

…E was not updated
Fix issue sonic-net#14916
Backport of sonic-net#14823

Why I did it

If you enable feature and then disable it, System Ready status change to Not Ready

root@qa-eth-vt01-2-3700v:/home/admin# config feature state dhcp_relay enabled 
root@qa-eth-vt01-2-3700v:/home/admin# show system-health sysready-status 
System is ready

Service-Name            Service-Status    App-Ready-Status    Down-Reason
----------------------  ----------------  ------------------  -------------
containerd              OK                OK                  -
dhcp_relay              OK                OK                  -
docker                  OK                OK                  -
...


root@qa-eth-vt01-2-3700v:/home/admin# config feature state dhcp_relay disabled 
root@qa-eth-vt01-2-3700v:/home/admin# show system-health sysready-status 
System is not ready - one or more services are not up

Service-Name            Service-Status    App-Ready-Status    Down-Reason
----------------------  ----------------  ------------------  -------------
containerd              OK                OK                  -
docker                  OK                OK                  -
...

A disabled feature should not affect the system ready status.

Work item tracking

• Microsoft ADO (number only):

How I did it

During the disable flow of dhcp_relay, it entered the dnsrvs_name list, which caused the SYSTEM_STATE key to be set to DOWN. Right after that, the dhcp_relay service was removed from the full service list, however, but, when it was removed from the dnsrvs_name, there was no flow to reset the system state back to UP even though there was no more services in down state.

How to verify it

root@qa-eth-vt01-2-3700v:/home/admin# config feature state dhcp_relay enabled 
root@qa-eth-vt01-2-3700v:/home/admin# show system-health sysready-status 

root@qa-eth-vt01-2-3700v:/home/admin# config feature state dhcp_relay disabled
root@qa-eth-vt01-2-3700v:/home/admin# show system-health sysready-status 

Should see
System is ready

Which release branch to backport (provide reason below if selected)

• 201811
• 201911
• 202006
• 202012
• 202106
• 202111
• 202205
• 202211

Tested branch (Please provide the tested image version)

Description for the changelog

Link to config_db schema for YANG module changes

A picture of a cute animal (not mandatory but encouraged)