Slides of the talk I gave at the Erlang meetup on the 20th of April 2010.

1. Looking
Under The Covers
Using SNMP to peek inside Erlang

2. About me
More stickers than a 40 years old RV!

3. About us
Developing a platform for a new breed of social
networking games
Scalability is a must
Back-end developed with Erlang/OTP
And lots of other good stuff
Front-end developed with Flex 4

4. We
Monitoring

5. The Expected
Monitoring the Erlang VM

6. The Fun Stuff
Monitoring your applications' guts

7. Agenda
SNMP 101
SNMP & Erlang
Agent configuration
Fixed and dynamic custom objects
Standard VM / OTP objects

8. SNMP 101
Simple Network Management Protocol
Introduced in 1988
Control & Monitoring
Anything with an IP address
Usually over UDP port 161
v2 is current, v3 is draft

9. SNMP 101, cont.

10. SNMP 101, end
SNMP world is a tree
With OIDs
All our Internet
are belong to DOD
You are 1.3.6.1.4.1.*

11. SNMP 101, end
Management Information Base (MIB)
Define what objects are handled by the agent
"Interesting" syntax
nodeName
OBJECT-TYPE
SYNTAX DisplayString
MAX-ACCESS read-only
STATUS current
DESCRIPTION "Erlang node name"
::= { staticOid 1 }

12. SNMP & Erlang
Full SNMP support:
Manager, agent, traps, queries, security...
Quickstart:
http://www.trapexit.org/SNMP_Quick_Start
Quicksand:
[3,6,1,4,1,193,19]}. % {ericsson otp}

13. Erlang SNMP Agent

14. Getting started: Configuration
Add all the agent boiler plate configuration
Create a custom MIB
Consider getting a Private Enterprise Number
Compile .mib to .bin
Compile .bin to .hrl (optional)
OIDs, default values, ranges

15. Getting started: Code
application:start(snmp)
snmpa:load_mibs(snmp_master_agent,
["snmp/MY-MIB"])
...
snmp_generic:variable_set(objectName,
objectValue)

16. Getting started: Tools
Command line
snmpwalk
snmpget
UI
tkmib
Monitoring
Zabbix, Zenoss, Nagios...
Graphing
Cacti...

17. Lab Time!
Monitor:
nodeName
DisplayString
gaugeValue
Gauge32

18. Creating Dynamic Objects
Use tables when OID is not fixed
Indexed rows
Dynamic OID composed of ASCII codes
1.3.6.1.4.1.35458.3.70.111.111.1
==
MyOID.Foo.1

19. SNMP Table: Code
SnmpRow = {Data1, Data2, ..., DataN}
snmpa_local_db:table_create_row(
tableName,
Index,
SnmpRow)
Index being one of Data...
Don't forget the .funcs configuration

20. Lab Time!
Monitor FS usage:
/ 74%
/dev 1%
/var/run 1%

21. Standard Erlang SNMP
OTP
Single agent
Table of all nodes in a cluster
General info & stats
OSMON
Local node
Detailed stats
Good luck to find these MIBs :)

22. Lab Time!
Monitor Erlang VM:
erlNode*
OTP-MIB
load*
OTP-OS-MON-MIB

23. Moar Infoz!

24. Thank you!
Raffle courtesy of

25. Source code
http://www.dossot.net/misc/files/erlang-snmp.tar.gz