Stop being lazy and writean event broker module already

Dave Josephsen

dave@dbg.com

WHY?!

The NEB interface is AWESOME

Interpreted automata is expensiveEspecially via global event handlers and/or performance-data hooks

You're more likely to make something I can use too!

How we're going to do this

Function pointers (and YOU)

What is the event broker?

How do we use it?

A few words of advice

Dissect a couple existing pluginsNagfs

DNX

Function Pointers are weird, but they make callbacks possible

void main() {

int c2f ( int c ) { return (9/5) *c+32; } int f2c ( int f ) { return (5/9) *(f-32); }

int convert (int input, int (*fPointer)(int)) { return fPointer(input);

}

void Go() {

int result=convert('72',&f2c);

}

}

Normal Function Declarations

wha??

Argument

Oh.. ok.

What is the event broker?

Nagios Event loop(kinda)

Event Broker added

How do we use it?

Write an init functionint nebmodule_init( int flags, char * args, nebmodule * handle)

Subscribe to the events you wantneb_register_callback(STUFF, handle, '1', &myhandler);

Write handler functions for each event you subscribed toint myhandler(int neb_event_type, nebstruct_stuff_data *ds)

Write a de-init functionint nebmodule_deinit(int flags, int reason){ return 0 }

How do we use it? (cont)

NEBCALLBACK_RAW_DATANEBCALLBACK_NEB_DATANEBCALLBACK_PROCESS_DATANEBCALLBACK_TIMED_EVENT_DATANEBCALLBACK_LOG_DATANEBCALLBACK_SYSTEM_COMMAND_DATANEBCALLBACK_EVENT_HANDLER_DATANEBCALLBACK_NOTIFICATION_DATANEBCALLBACK_SERVICE_CHECK_DATANEBCALLBACK_HOST_CHECK_DATANEBCALLBACK_COMMENT_DATANEBCALLBACK_DOWNTIME_DATANEBCALLBACK_FLAPPING_DATANEBCALLBACK_PROGRAM_STATUS_DATANEBCALLBACK_HOST_STATUS_DATANEBCALLBACK_SERVICE_STATUS_DATANEBCALLBACK_ADAPTIVE_PROGRAM_DATANEBCALLBACK_ADAPTIVE_HOST_DATANEBCALLBACK_ADAPTIVE_SERVICE_DATANEBCALLBACK_EXTERNAL_COMMAND_DATANEBCALLBACK_AGGREGATED_STATUS_DATANEBCALLBACK_RETENTION_DATANEBCALLBACK_CONTACT_NOTIFICATION_DATANEBCALLBACK_CONTACT_NOTIFICATION_METHOD_DATANEBCALLBACK_ACKNOWLEDGEMENT_DATANEBCALLBACK_STATE_CHANGE_DATANEBCALLBACK_CONTACT_STATUS_DATANEBCALLBACK_ADAPTIVE_CONTACT_DATA

include/nebcallbacks.h

neb_register_callback(NEBCALLBACK_TIMED_EVENT_DATA, handle, '1', &handler);

/* fill struct with relevant data */ ds.type=type; ds.flags=flags; ds.attr=attr; ds.timestamp=get_broker_timestamp(timestamp);

ds.event_type=event->event_type; ds.recurring=event->recurring; ds.run_time=event->run_time; ds.event_data=event->event_data; ds.event_ptr=(void *)event;

/* make callbacks */ neb_make_callbacks(NEBCALLBACK_TIMED_EVENT_DATA,(void *)&ds);

base/broker.c

include/broker.h

#define NEBTYPE_TIMEDEVENT_ADD #define NEBTYPE_TIMEDEVENT_REMOVE #define NEBTYPE_TIMEDEVENT_EXECUTE#define NEBTYPE_TIMEDEVENT_DELAY#define NEBTYPE_TIMEDEVENT_SKIP#define NEBTYPE_TIMEDEVENT_SLEEP

int handler(int neb_event_type, nebstruct_timed_event_data *ds)

How do we use it? (cont)

Everything is a struct

Every struct is globally scoped

The sky is the limitenumerate/add/remove events from the queue

reconfigure hosts/services post-runtime

export/import data from/to whatever

process check data, inject/delete check results

GO CRAZY!

Some words of advice

There's a hello world module in contrib

Write your thingy as a stand-alone thingy first, and then convert it to an EH function

Start simple, and then build up

Avoid Threads(run them in a separate process)

The DNX guys have pre-packaged the headers for various versions of Nagios (zomgthankyou)

Nagfs

DNX

External process IPC

Service check preemption

Check result injection

OK BYE!

(and speaking of buy...)

http://dnx.sourceforge.net/

http://old.nagios.org/developerinfo/

http://nagios.larsmichelsen.com/event_broker_options/

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2012

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