Nagios event broker NEB module for adding a new service without restarting

helloworld.c

/*

Proof-of-concept to add services to Nagios without reload/restarts.
By Renzo Toma / 2017-03-01

Tested on Nagios 3.5.1.

New services are not visible using the Nagios CGI scripts as the new services
are missing from the objects.cache file. Workaround: use livestatus + Thruk.

*/



// allow access to service ptr fields
#define NSCORE 1

#include "../include/config.h"

/* include (minimum required) event broker header files */
#include "../include/nebmodules.h"
#include "../include/nebcallbacks.h"

/* include other event broker header files that we need for our work */
#include "../include/nebstructs.h"
#include "../include/broker.h"

/* include some Nagios stuff as well */
#include "../include/config.h"
#include "../include/common.h"
#include "../include/nagios.h"

/* specify event broker API version (required) */
NEB_API_VERSION(CURRENT_NEB_API_VERSION);


void *helloworld_module_handle = NULL;
void helloworld_function(char *);

char *log_prefix = "HELLOWORLD";
int interval = 5;   // seconds


int nebmodule_init(int flags, char *args, nebmodule *handle) {
	time_t current_time;

	/* save our handle */
	helloworld_module_handle = handle;

    logit(NSLOG_INFO_MESSAGE, TRUE, "%s: module loaded. Build: %s %s", log_prefix, __DATE__, __TIME__);

    // register our callback as scheduled event
	time(&current_time);
	schedule_new_event(EVENT_USER_FUNCTION, TRUE, current_time + interval, TRUE, interval, NULL, TRUE, (void *)helloworld_function, NULL, 0);

    logit(NSLOG_INFO_MESSAGE, TRUE, "%s: callback will be executed every %d seconds", log_prefix, interval);

	return 0;
}


int nebmodule_deinit(int flags, int reason) {
    logit(NSLOG_INFO_MESSAGE, TRUE, "%s: module unloaded", log_prefix);
	return 0;
}


void helloworld_function(char *arg) {

    char *contactgroup_name = "admins";

    char *host_name = "localhost";
    char *service_description = "foo";
    char *display_name = "foo";
    char *check_period = "24x7";

    int initial_state = 0;
    int max_check_attempts = 4;
    int parallelize_check = 1;
    int passive_checks_enabled = 1;

    double check_interval = 0.5;    // 1 = 1 minute
    double retry_interval = 0.5;
    double notification_interval = 5;
    double first_notification_delay = 0;

    char *notification_period = "24x7";

    int notify_on_recovery = 1;
    int notify_on_unknown = 1;
    int notify_on_warning = 1;
    int notify_on_critical = 1;
    int notify_on_flapping = 1;
    int notify_on_downtime = 1;
    int notifications_enabled = 1;
    int is_volatile = 0;

    char *event_handler = NULL;
    int event_handler_enabled = 1;
    char *check_command = "check_local_load!5.0,4.0,3.0!10.0,6.0,4.0";
    int active_checks_enabled = 1;

    int flap_detection_enabled = 1;
    double low_flap_threshold = 0.0;
    double high_flap_threshold = 0.0;
    int flap_detection_on_ok = 0;
    int flap_detection_on_warning = 0;
    int flap_detection_on_unknown = 0;
    int flap_detection_on_critical = 0;

    int stalk_on_ok = 0;
    int stalk_on_warning = 0;
    int stalk_on_unknown = 0;
    int stalk_on_critical = 0;

    int process_perf_data = 1;
    int failure_prediction_enabled = 1;
    char *failure_prediction_options = NULL;
    int check_freshness = 0;
    int freshness_threshold = 0;
    char *notes = NULL;
    char *notes_url = NULL;
    char *action_url = NULL;
    char *icon_image = NULL;
    char *icon_image_alt = NULL;
    int retain_status_information = 1;
    int retain_nonstatus_information = 1;
    int obsess_over_service = 1;



    // find host by name
    host *my_host = find_host(host_name);
    if (my_host == NULL) {
        logit(NSLOG_RUNTIME_WARNING, TRUE, "%s: host '%s' not found", log_prefix, host_name);
        return;
    }




    // find service
    service *my_service = find_service(my_host->name, service_description);
    if (my_service != NULL) {
        logit(NSLOG_INFO_MESSAGE, TRUE, "%s: service '%s' on host '%s' is present. Last/next check: %d/%d",
            log_prefix, my_service->description, my_service->host_name,
            my_service->last_check, my_service->next_check);
        return;
    }

    // add service
    my_service = add_service(my_host->name, service_description, display_name, check_period, initial_state, max_check_attempts, parallelize_check, passive_checks_enabled, check_interval, retry_interval, notification_interval, first_notification_delay, notification_period, notify_on_recovery, notify_on_unknown, notify_on_warning, notify_on_critical, notify_on_flapping, notify_on_downtime, notifications_enabled, is_volatile, event_handler, event_handler_enabled, check_command, active_checks_enabled, flap_detection_enabled, low_flap_threshold, high_flap_threshold, flap_detection_on_ok, flap_detection_on_warning, flap_detection_on_unknown, flap_detection_on_critical, stalk_on_ok, stalk_on_warning, stalk_on_unknown, stalk_on_critical, process_perf_data, failure_prediction_enabled, failure_prediction_options, check_freshness, freshness_threshold, notes, notes_url, action_url, icon_image, icon_image_alt, retain_status_information, retain_nonstatus_information, obsess_over_service);

    if (my_service == NULL) {
        logit(NSLOG_RUNTIME_WARNING, TRUE, "%s: can not add service '%s' on host '%s'",
            log_prefix, my_host->name, service_description);
        return;
    }

    logit(NSLOG_INFO_MESSAGE, TRUE, "%s: added service '%s' on host '%s'",
        log_prefix, my_service->description, my_service->host_name);



    // required, otherwise service is not linked to host
    my_service->host_ptr = my_host;

    // required, otherwise service view in thruk does not work
    add_service_link_to_host(my_host, my_service);


    char *command_buf = (char *)strdup(check_command);
    char *command_name = strtok(command_buf, "!");
    command *temp_command = find_command(command_name);
    if (temp_command == NULL) {
        logit(NSLOG_RUNTIME_WARNING, TRUE, "%s: can not find check command '%s'",
            log_prefix, command_name);
        return;
    }
    // required, otherwise check stays in pending
    my_service->check_command_ptr = temp_command;
    logit(NSLOG_INFO_MESSAGE, TRUE, "%s: check command '%s' verified & linked",
        log_prefix, command_name);



    // add contactgroup to service
    contactgroupsmember *temp_contactgroupsmember = add_contactgroup_to_service(my_service, contactgroup_name);
    if (temp_contactgroupsmember == NULL) {
        logit(NSLOG_RUNTIME_WARNING, TRUE, "%s: can not add contactgroup '%s'",
            log_prefix, contactgroup_name);
        return;
    }
    logit(NSLOG_INFO_MESSAGE, TRUE, "%s: contactgroup '%s' was added to service",
        log_prefix, contactgroup_name);




    timeperiod *temp_timeperiod = NULL;
    temp_timeperiod = find_timeperiod(my_service->check_period);
    if(temp_timeperiod == NULL) {
        logit(NSLOG_RUNTIME_WARNING, TRUE, "%s: can not find check period '%s'",
            log_prefix, my_service->check_period);
        return;
    }
    // required, otherwise rescheduling does not work
    my_service->check_period_ptr = temp_timeperiod;
    logit(NSLOG_INFO_MESSAGE, TRUE, "%s: check period '%s' verified & linked",
        log_prefix, my_service->check_period);



    // schedule for near future
    time_t preferred_time = time(0) + 10;
    schedule_service_check(my_service, preferred_time, CHECK_OPTION_NONE);

    logit(NSLOG_INFO_MESSAGE, TRUE, "%s: service has been scheduled", log_prefix);

    return;
}

Thruk screenshot showing the 'foo' service: