Docker SNMP Proxy

This is an SNMP Proxy that collect dynamically the environment variables, with an specific prefix, of each container created by docker-compose, and with them, set up the SNMP Daemon to forward multiple SNMP OIDs to their respective container.

This solution are based on docker-gen project, developed by ©Jason Wilder.

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• Docker Image
• Requirements
• Limitations
• How-to
• Example
• To-Do

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Docker Image

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Requirements

• docker-engine >= 1.12
• docker-compose >= 1.8.1
• docker-compose must run as root user, to be able to map 161(udp) port.
• Map docker.sock, to be able to access the docker-engine API.

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Limitations

• SNMP Community harcoded to 'public' for now

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How-to

Lo primero que debemos hacer es configurar el composer para que la imagen 'snmp-proxy':

• Tenga mapeado el puerdo 161 (udp)
• Tenga montado el socket del docker-engine.

services:
  snmp-proxy:
    image: mgvazquez/snmp-proxy
    hostname: snmp-proxy01
    container_name: snmp-proxy
    ports:
      - "161:161/udp"
    volumes:
      - /var/run/docker.sock:/tmp/docker.sock:ro

Luego lo que debemos hacer es configurar cada container al que querramos consultar via SNMP:

• Que levante el SNMP Daemon
• Que exponga el puerdo 161 (udp)
• Que disponibles las OIDs a consultar
• Setear las variables de entorno con las OIDs que expondrá.

[...]
snmp-host1:
  image: elcolio/net-snmp
  hostname: snmp-host01
  command: snmpd -Lo -f -V -c /etc/snmp/snmpd.conf
  container_name: snmp-host1
  ports:
    - 161/udp
  environment:
    - SNMPOID_1=.1.3.6.1.2.1.1.5.0
    - SNMPOID_2=.1.3.6.1.2.1.1.6.0
    - SNMPOID_<n>=.x.x.x

[...]

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Example

$ sudo docker-compose up
[sudo] password for <user>:
Starting snmp-proxy
Starting snmp-host3
Starting snmp-host1
Starting snmp-host2
Attaching to snmp-proxy, snmp-host3, snmp-host2, snmp-host1
snmp-proxy    | 2016-11-15 19:34:02,628 CRIT Supervisor running as root (no user in config file)
snmp-proxy    | 2016-11-15 19:34:02,629 INFO Included extra file "/etc/supervisord.d/docker-gen.conf" during parsing
snmp-proxy    | 2016-11-15 19:34:02,629 INFO Included extra file "/etc/supervisord.d/snmpd.conf" during parsing
snmp-proxy    | 2016-11-15 19:34:02,635 INFO RPC interface 'supervisor' initialized
snmp-proxy    | 2016-11-15 19:34:02,635 CRIT Server 'unix_http_server' running without any HTTP authentication checking
snmp-proxy    | 2016-11-15 19:34:02,635 INFO supervisord started with pid 1
snmp-host3    | error finding row index in _ifXTable_container_row_restore
snmp-host3    | NET-SNMP version 5.7.2
snmp-host2    | error finding row index in _ifXTable_container_row_restore
snmp-host2    | NET-SNMP version 5.7.2
snmp-host1    | error finding row index in _ifXTable_container_row_restore
snmp-host1    | NET-SNMP version 5.7.2
snmp-proxy    | 2016-11-15 19:34:03,637 INFO spawned: 'snmpd' with pid 17
snmp-proxy    | 2016-11-15 19:34:03,639 INFO spawned: 'docker-gen' with pid 18
snmp-proxy    | 2016-11-15 19:34:03,772 INFO waiting for snmpd to stop
snmp-proxy    | 2016-11-15 19:34:03,776 INFO stopped: snmpd (exit status 0)
snmp-proxy    | 2016-11-15 19:34:03,779 INFO spawned: 'snmpd' with pid 27
snmp-proxy    | 2016-11-15 19:34:04,809 INFO success: snmpd entered RUNNING state, process has stayed up for > than 1 seconds (startsecs)
snmp-proxy    | 2016-11-15 19:34:04,809 INFO success: docker-gen entered RUNNING state, process has stayed up for > than 1 seconds (startsecs)
[...]

$ snmpget -v2c -c public localhost .1.3.6.1.2.1.1.5.0
iso.3.6.1.2.1.1.5.0 = STRING: "snmp-host01"

[...]
snmp-host1    | Received SNMP packet(s) from UDP: [172.18.0.2]:58390->[172.18.0.3]:161
snmp-host1    |   GET message
snmp-host1    |     -- SNMPv2-MIB::sysName.0
[...]

$ snmpget -v2c -c public localhost .1.3.6.1.2.1.1.6.0
iso.3.6.1.2.1.1.6.0 = STRING: "Unknown (edit /etc/snmp/snmpd.conf)"

[...]
snmp-host2    | Received SNMP packet(s) from UDP: [172.18.0.2]:45859->[172.18.0.5]:161
snmp-host2    |   GET message
snmp-host2    |     -- SNMPv2-MIB::sysLocation.0
[...]

$ snmpget -v2c -c public localhost .1.3.6.1.2.1.1.7.0
iso.3.6.1.2.1.1.7.0 = No Such Instance currently exists at this OID

[...]
snmp-host3    | Received SNMP packet(s) from UDP: [172.18.0.2]:53948->[172.18.0.4]:161
snmp-host3    |   GET message
snmp-host3    |     -- SNMPv2-MIB::sysServices.0
[...]

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To-Do

• Set up SNMP Communities per host (SNMP Contexts)

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