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[SNMP][IPv6]: Fix SNMP IPv6 reachability issue in certain scenarios #15487

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merged 12 commits into from
Jul 12, 2023
Merged

[SNMP][IPv6]: Fix SNMP IPv6 reachability issue in certain scenarios #15487

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8e7aa23
[SNMP][IPv6]: Fix SNMP IPv6 reachability issue in certain scenario
SuvarnaMeenakshi Jun 15, 2023
cf2f69d
snmpd to listen on loopback0 ip only if interface exists.
SuvarnaMeenakshi Jun 15, 2023
8b1359f
Update minigraph parser to update SNMP_AGENT_ADDRESS_CONFIG
SuvarnaMeenakshi Jun 21, 2023
6d0c64f
Add unit-test for minigraph change.
SuvarnaMeenakshi Jun 27, 2023
27ed71e
Update minigraph parser and add unit-test.
SuvarnaMeenakshi Jun 27, 2023
da40251
Moved logic to minigraph parser to add right IP addresses.
SuvarnaMeenakshi Jun 27, 2023
6859d0d
Remove logic to get docker0 ip.
SuvarnaMeenakshi Jun 27, 2023
e9cdf0a
Modify function name
SuvarnaMeenakshi Jun 27, 2023
40ba8f1
Modify to simpler change to easily backport to
SuvarnaMeenakshi Jun 29, 2023
15bf353
Merge remote-tracking branch 'origin/master' into HEAD
SuvarnaMeenakshi Jun 29, 2023
d1e4de4
Merge remote-tracking branch 'origin/master' into HEAD
SuvarnaMeenakshi Jul 10, 2023
817396c
Modify as per review comment
SuvarnaMeenakshi Jul 11, 2023
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28 changes: 27 additions & 1 deletion dockers/docker-snmp/snmpd.conf.j2
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Original file line number Diff line number Diff line change
Expand Up @@ -13,12 +13,38 @@
# AGENT BEHAVIOUR
#

# Listen for connections on all ip addresses, including eth0, ipv4 lo
# Listen for connections on ip addresses based on configuration
#
# if SNMP_AGENT_ADDRESS_CONFIG is present
# use SNMP_AGENT_ADDRESS_CONFIG
# elif either MGMT_INTERFACE or LOOPBACK_INTERFACE
# use management and loopback ip addresses
# use docker0 ipv4 and ipv6 address
# else if none of the above config is present
# listen on any IP
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@qiluo-msft qiluo-msft Jun 19, 2023 •
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The logic is complex.
how about minigraph.py just generated correct SNMP_AGENT_ADDRESS_CONFIG?

  1. single-asic: bind to mgmt and lo
  2. multi-asic: bind to mgmt and docker0 #Closed

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I think docker0 IP is not part of user config, you can use template here.

However, mgmt IP, lo IP are from user config, it is natural to add them into ConfigDB SNMP_AGENT_ADDRESS_CONFIG table.

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I see the challenge of determine single/multi-asic in minigraph.py. So it is okay to keep complex code here.

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I have modified the snmpd.conf.j2 template to use management and loopback IP for single asic platform.
With this, we could backport to previous branches to ensure that we could use ipv6 .

Next step is to:

  1. If the change to modify to use bridge network for snmp docker is merged in, we could add NAT rule for single asic platform similar to multi-asic platform.
  2. After that change, will update minigraph parser to update SNMP_AGENT_ADDRESS_CONFIG table with management IP and docker0 IP for both single and multi-asic platform that way minigraph parser need not have the logic to differentiate between single and multi-asic platform.
  3. Remove the changes in snmpd.conf.j2 and directly use SNMP_AGENT_ADDRESS_CONFIG which will be updated by minigraph parser.


{% if SNMP_AGENT_ADDRESS_CONFIG %}
{% for (agentip, port, vrf) in SNMP_AGENT_ADDRESS_CONFIG %}
agentAddress {{ agentip }}{% if port %}:{{ port }}{% endif %}{% if vrf %}%{{ vrf }}{% endif %}{{ "" }}
{% endfor %}
{% elif MGMT_INTERFACE is defined or LOOPBACK_INTERFACE is defined%}
{% if MGMT_INTERFACE is defined %}
{% for if, ip in MGMT_INTERFACE %}
agentAddress {{ ip.split('/')[0] }}
{% endfor %}
{% endif %}
{% if LOOPBACK_INTERFACE is defined and loopback0_exists %}
{% for lo in LOOPBACK_INTERFACE %}
{% if lo | length == 2 %}
agentAddress {{ lo[1].split('/')[0] }}
{% endif %}
{% endfor %}
{% endif %}
# Listen on docker0 IP address to support multi-asic platform
{% if docker0_v4 and docker0_v6 %}
agentAddress {{ docker0_v4 }}
agentAddress {{ docker0_v6 }}
{% endif %}
{% else %}
agentAddress udp:161
agentAddress udp6:161
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11 changes: 11 additions & 0 deletions dockers/docker-snmp/start.sh
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Expand Up @@ -16,11 +16,22 @@ mkdir -p /etc/ssw /etc/snmp
# Parse snmp.yml and insert the data in Config DB
/usr/bin/snmp_yml_to_configdb.py

DOCKER0_V4=$(ip -4 addr show docker0 | grep -oP '(?<=inet\s)\d+(\.\d+){3}')
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@qiluo-msft qiluo-msft Jun 23, 2023 •
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docker0

More secure container will bring better isolation between host and container. There is no access to docker0 insider container in future.

You may consider passing env var while docker create. #Closed

DOCKER0_V6=$(ip -6 addr show docker0 scope global | grep -oP '(?<=inet6\s)[0-9a-fA-F:]+')
# Loopback0 interface will not exist on multi-asic device
if ip link show Loopback0 >/dev/null 2>&1; then
LOOPBACK0_EXITS=true
fi

ADD_PARAM=$(printf '%s {"docker0_v4":"%s","docker0_v6":"%s","loopback0_exists":"%s"}' \
"-a" "$DOCKER0_V4" "$DOCKER0_V6" "$LOOPBACK0_EXITS")

SONIC_CFGGEN_ARGS=" \
-d \
-y /etc/sonic/sonic_version.yml \
-t /usr/share/sonic/templates/sysDescription.j2,/etc/ssw/sysDescription \
-t /usr/share/sonic/templates/snmpd.conf.j2,/etc/snmp/snmpd.conf \
$ADD_PARAM \
"

sonic-cfggen $SONIC_CFGGEN_ARGS
Expand Down