[docker-snmp] Provides a config file for the polling interval in sonic_ax_impl

[PeterTSW-EC]

Why I did it

By default, SONiC does not restrict the CPU usage of the system containers.
This caused the SNMP container to consume 100% CPU.

A feasible approach is to define a configured file to adjust the SNMP container's CPU usage when required under specific scenarios.
The interval of the polling tasks in the SNMP process also affects the fundamental CPU usage consumed by the SNMP process. So, the configure file also needs to provide the option to change the update intervals in the SNMP process.

Work item tracking

• Microsoft ADO (number only):

How I did it

• Add to support the features:

1. Restrict the CPU usage of SNMP container through the file: snmp_daemon_control.json
2. Adjust the polling intervals in SNMP process through the file: snmp_daemon_control.json
   Note: the file snmp_daemon_control.json located at /usr/share/sonic/device/<device_model>/snmp_daemon_control.json

How to verify it

Use the command "docker exec -it snmp ps -x" to examine the interval update.
The following box shows an example of setting the SNMP polling interval to 5 seconds to 10 seconds.

root@as7816-64x:/# docker exec -it snmp ps -x
    PID TTY      STAT   TIME COMMAND
      1 pts/0    Ss+    0:00 /usr/bin/python3 /usr/local/bin/supervisord
     18 pts/0    S      0:00 python3 /usr/bin/supervisor-proc-exit-listener --co
     27 pts/0    Sl     0:00 /usr/sbin/rsyslogd -n -iNONE
     32 pts/0    Sl     0:39 python3 -m sonic_ax_impl
     65 pts/1    Rs+    0:00 ps -x
root@as7816-64x:/# cat /usr/share/sonic/device/x86_64-accton_as7816_64x-r0/snmp_daemon_control.json
{
        "update_frequency": 10
}

root@as7816-64x:/# systemctl restart snmp
root@as7816-64x:/# docker exec -it snmp ps -x
    PID TTY      STAT   TIME COMMAND
      1 pts/0    Ss+    0:00 /usr/bin/python3 /usr/local/bin/supervisord
     18 pts/0    S      0:00 python3 /usr/bin/supervisor-proc-exit-listener --co
     27 pts/0    Sl     0:00 /usr/sbin/rsyslogd -n -iNONE
     32 pts/0    Sl     0:01 python3 -m sonic_ax_impl -f 10
     35 pts/1    Rs+    0:00 ps -x

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

• 201811
• 201911
• 202006
• 202012
• 202106
• 202111
• 202205
• 202211
• 202305
• 202311

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)