Enable a Rule from TrafficScript or External Program

[fahimbfarook]

Hi, Is it possible to enable or disable a rule by a TrafficScript (some other rule) or external program.

Infact my requirement is this. - I need to health check the DB periodically and if DB fails, I need to redirect requests to a maintenance page.

In order to monitor the DB, I thought of writing an external program monitor which emits a custom-event if DB fails. Then I thought of writing a custom Alert/Action which is triggered by that custom-event and this action enables the maintenance page rule. Is this approach correct? Is there a better way for achieving the same?

Thanks in Advance.

[jochenmaurer]

you are able to disable a rule from external e.g. through zcli program.

but nevertheless, imho the best way to achieve what you want would be a health-check within a pool.

Health Checks are done via nodes (which is normally not your DB Server), so what we've done is creating a small page within our app-server (=node), this page just checks if DB is running, and returns OK/NOK. And we implemented a custom-healthcheck, calling this page via http request, and checking if return body is OK.

If there is a DB-Problem, all nodes will be disabled automatically, and you can do something different through trafficscript "pool.activenodes" function (e.g. showing maintenance via .http.sendresponse)

[fahimbfarook]

Appreciate if you could explain the following further.

"And we implemented a custom-healthcheck, calling this page via http request, and checking if return body is OK. If there is a DB-Problem, all nodes will be disabled automatically,.."

"custom-healthcheck" here means a custom health monitor which will run periodically? or a rule applied to the virtual server?

Also cold you please provide some links/ resources on how to enable/ disable rules from external programs/ other scripts?

[jochenmaurer]

we are using a http-healthcheck (Pools - Health Monitoring),

e.g. check your  nodes via   "/checkdb.php" (depending on your environment php maybe not suitable).

this php-script checks DB Connectivity, and returns OK/NOK

(we are not using php, so i can't provide a example, our healthcheck is part of our own application)

within the health-monitor, just define the "body_regex:" as "OK".

If you have setup this, STM will check your nodes every few seconds if this URL still returns OK, if not, the node will be marked as failed.

then, within a rule (assigned to your vserver), you can check, if nodes for your pool are available

if (pool.activenodes("yourpoolname") < 1 {

http.sendresponse(....your maintenance message);

}

if you want to use zcli, there is full documentation with functions...

[pwallace_1 · Accepted solution]

If you really need to have external control of rules in Stingray, you should be able to set up a script fairly easily with Python and FlyScript - check out the FlyScript pages on: https://splash.riverbed.com/community/product-lines/flyscript

There are a few predefined scripts already in the Stingray module, including:

change_rule(self, vserver, rule, enable=True, request=True, response=True);

If you want to create something more specific, you can see how this constructs a JSON request to access the REST API for Stingray. There is detailed documentation on the REST API on the Stingray download pages:

https://support.riverbed.com/content/support/software/stingray/traffic-manager.html

[fahimbfarook]

Hi Jochen Maurer,

Appreciate if you could calrify the following.

As you said:

"If you have setup this, STM will check your nodes every few seconds if this URL still returns OK, if not, the node will be marked as failed.

then, within a rule (assigned to your vserver), you can check, if nodes for your pool are available

if (pool.activenodes("yourpoolname") < 1 {

http.sendresponse(....your maintenance message);

}

"

However I saw a configuration under Virtual Server > Connection Management > Connection Error Settings:

that we can configure an error page. I'm not quite sure whether configuring an error page (i.e. maintanace-page.html) here has the same effect as doing like the following

if (pool.activenodes("yourpoolname") < 1 {

http.sendRedirect("maintanace-page.html");

}

Could you please shed some light on this