mvrf_avoid_snmp_yml_config: made changes to pass SNMP config from con…

[kannankvs]

This PR is based on the new comments given for the already merged PR3586.
By design, snmp.yml provides some static configurations that are not supported in ConfigDB (redis).
Hence, the configurations that got added in snmp.yml as part of PR3586 is being removed.
Instead, the configurations are directly read from ConfigDB and rendered in snmpd.conf.j2 inside snmp docker container to generate the snmpd.conf directly without using snmp.yml.
These are tested by configuring the snmpagentaddress and snmptrap commands.
@qiluo-msft : Request you to kindly review, approve, merge & cherrypick to 201911.

[kannankvs]

retest this please

[qiluo-msft]

{{ "" }} [](start = 94, length = 8)

Why you need this?

Could you give some samples of input and render results?

[kannankvs]

@qiluo-msft : I assume you mean the last {{ "" }}.
I am using the following example configuration in config_db,

    "SNMP_AGENT_ADDRESS_CONFIG": {
        "1.1.1.1||": {},
        "2.2.2.2||": {}
    },

Without this {{ "" }}, if we configure more than one agentAddress, they all come in same line in snmpd.conf.
Example: In snmpd.conf without this {{ "" }} as follows.

agentAddress 1.1.1.1agentAddress 2.2.2.2

With this {{ "" }}, a new line is inserted between agentAddress.
Example: In snmpd.conf with this {{ "" }} as follows.

agentAddress 1.1.1.1
agentAddress 2.2.2.2

[qiluo-msft]

Not true. Could you please test again? I tested and got the expected multiple line output.

---

In reply to: 371142042 [](ancestors = 371142042)

[kannankvs]

@qiluo-msft : My previous example was from my device only. I am not sure why you are not seeing same result as mine. I used the commands (given below) to configure. You can try once using the commands as well.

I redid the configuration and the result is given below.

root@sonic-s6100-07:~# config snmpagentaddress add 1.1.1.1
root@sonic-s6100-07:~# config snmpagentaddress add 2.2.2.2

root@sonic-s6100-07:~# docker exec -it snmp bash
root@sonic-s6100-07:/# cat /etc/snmp/snmpd.conf | grep agentAdd
agentAddress 1.1.1.1agentAddress 2.2.2.2
root@sonic-s6100-07:/# 

Above is the output from my device without that {{ "" }}. If you are 100% sure that {{ "" }} is not required, I can remove it.

[qiluo-msft]

I test the image built in this PR https://sonic-jenkins.westus2.cloudapp.azure.com/job/mellanox/job/buildimage-mlnx-all-pr/2154/artifact/target/sonic-mellanox.bin. Please check if the test is valid and recheck yours?

admin@sonic:~$ docker exec -it snmp bash
root@sonic:/# redis-cli -n 4
127.0.0.1:6379[4]> hset "SNMP_AGENT_ADDRESS_CONFIG|1.1.1.1||" "" ""
(integer) 1
127.0.0.1:6379[4]> hset "SNMP_AGENT_ADDRESS_CONFIG|2.2.2.2||" "" ""
(integer) 1
127.0.0.1:6379[4]> exit
root@sonic:/# sonic-cfggen -d -y /etc/sonic/snmp.yml -t /usr/share/sonic/templates/snmpd.conf.j2
###############################################################################
# Managed by sonic-config-engine
###############################################################################
#
# EXAMPLE.conf:
#   An example configuration file for configuring the Net-SNMP agent ('snmpd')
#   See the 'snmpd.conf(5)' man page for details
#
#  Some entries are deliberately commented out, and will need to be explicitly activated
#
###############################################################################
#
#  AGENT BEHAVIOUR
#

#  Listen for connections on all ip addresses, including eth0, ipv4 lo
#
agentAddress 1.1.1.1
agentAddress 2.2.2.2

[kannankvs]

@qiluo-msft : Unfortunately I dont have any mellanox device to test the mellanox bin. I tested in Dell device that uses sonic-broadcom.bin. I am using Jan 22 image from Jenkins.
Doubt: If we have this {{ "" }}. will it create any issue? Since it always gives error in my setup, can we retain it and merge?

[qiluo-msft]

Ok, I double checked my test case and it is not true.

[qiluo-msft]

Minor issues

[kannankvs]

Minor issues

@qiluo-msft : Is this a different comment? Can you please explain?