plans

[Jan-Henrik Haukeland]

Hi

I'm working with the external command function. It's a bit complicated
to integrate this. You may rememeber that we originally planned to
first include this in an alert statement like: alert `/bin/xyzzy .. `

After hacking around in the monit code I think it is a better idea to
create a standalone statement for this. This statement can then also
be combined with other statements as a regular action.

The new statement can be called 'exec' and will look much like the
alert statement in standalone form. Here's the syntax:

 EXEC program [{events}] 

An example in free-form would look like:

 check ...
  exec "/bin/xyzzy -option 1 ... -option N  argument1.. argumentN" on {
    timeout, restart, checksum, resource, stop, timestamp }

Coupled with on of the "if" tests it would look like (notice that
[{events}] will not be a part in this context):

 if timestamp /usr/local/apache/conf/httpd.conf was changed then 
  exec "/bin/xyzzy -option 1 ... -option N  argument1.. argumentN"

 if cpu usage > 99% then exec "/sbin/shutdown -t 1 bye, bye"


ACTIONS:
-------

1) 
Implementing this will make use of all the calls to smtp_alert_xxx and
the smtp_alert(Service_T s, int event, char *optmsg, va_list ap)
function that now dispatch alerts will have a test equal to the
maillist test for execs as in this function skeleton:

static void smtp_alert(Service_T s, int event, char *optmsg, va_list ap) {

  ASSERT(s);

  if(s->maillist) {
    for(all objects in s->maillist)
     if(event == maillist[i].events) then
       do smtp alerts 
  }

NEW:
  if(s->execlist) {
    for(all objects in s->execlist)
      if(event == execlist[i].events) then
        do spawn program
  }

}

2) 
Since alert.c will be used in a more general term I suggest that we
change the function names from smtp_alert_xxx to simply alert_xxxx


3) 
Change the Mail_T object and extract the events into a standalone
object so they can be reused in the new Exec_T object. Changes:

/** Defines a mailinglist object */
typedef struct mymail {
  char *to;                         /**< Mail address for alert notification */
  char *from;                                     /**< The mail from address */
  char *subject;                                       /**< The mail subject */
  char *message;                                       /**< The mail message */
  char *opt_message;                 /**< An optional message used in alerts */
  int  alert_on_timeout;       /**< If TRUE, alert user when service timeout */
  int  alert_on_restart;  /**< If TRUE, alert user when the service restarts */
  int  alert_on_checksum;    /**< If TRUE, alert user when the checksum fail */
  int  alert_on_resource;     /**< If TRUE, alert user when resources exceed */
  int  alert_on_stop;          /**< If TRUE, alert user when service stopped */
  int  alert_on_timestamp;  /**< If TRUE, alert user when the timestamp fail */

  /** For internal use */
  struct mymail *next;                          /**< next recipient in chain */
} *Mail_T;


is changed to:

/** Defines an alert object */
typedef struct myalert {
  int  alert_on_timeout;       /**< If TRUE, alert user when service timeout */
  int  alert_on_restart;  /**< If TRUE, alert user when the service restarts */
  int  alert_on_checksum;    /**< If TRUE, alert user when the checksum fail */
  int  alert_on_resource;     /**< If TRUE, alert user when resources exceed */
  int  alert_on_stop;          /**< If TRUE, alert user when service stopped */
  int  alert_on_timestamp;  /**< If TRUE, alert user when the timestamp fail */
} Alert_T;


/** Defines a mailinglist object */
typedef struct mymail {
  char *to;                         /**< Mail address for alert notification */
  char *from;                                     /**< The mail from address */
  char *subject;                                       /**< The mail subject */
  char *message;                                       /**< The mail message */
  char *opt_message;                 /**< An optional message used in alerts */
  Alert_T alerts;                    /*< Alerts defined for this mail object */

  /** For internal use */
  struct mymail *next;                          /**< next recipient in chain */
} *Mail_T;


And here is the new preliminary exec object:


/** Defines an alien program to execute upon alert or an action. */
typedef struct myexec {
  Alert_T events;         /**< Events triggering this program to be executed */
  Command_T program;                       /**< The external program to call */
  
  /** For internal use */
  struct myexec *next;                   /**< next external program in chain */
} *Exec_T;


4)
All this requires changes "all over the place" and if you have
anything to checkin please let me know now.

5) 
If someone feels for it a cleanup of monit.pod would be nice and also
adding a GRAMMAR SECTION defining the grammar would maybe also be nice
or what do you think?


Opinions on this plan, anyone?

-- 
Jan-Henrik Haukeland