HTTP health monitor using iRule

Welcome Prasad!

 

 

This one probably belongs over in the Management, Reporting and Logging area:

 

http://devcentral.f5.com/Community/TopicGroups/tabid/1082223/asg/44/showtab/groupforums/Default.aspx

 

 

That being said here are few areas you might want to check out..

 

 

Tips for health monitors:

 

http://devcentral.f5.com/wiki/default.aspx/AdvDesignConfig/ApplicationHealthMonitoring.html

 

 

Here is a good post for creating a simple health monitor:

 

http://devcentral.f5.com/Community/GroupDetails/tabid/1082223/asg/44/aft/61823/showtab/groupforums/Default.aspx

Check that area and post out. If you still run into an issue when trying to configure the monitor you might post a little more detail and provide the nitty gritty details of what your monitor needs to check, url path, timeouts on the monitor and stuff like that.

Hi Nathan,

 

 

Thanks for reply , I have gone through those link & posts but seems to be quite heavy for me ( at this stage at least :( !!!. ) , My requirment is like this

 

 

We have two webserver with three websites.

 

 

IP SERVER site

 

x.x.x.1 WebSrv_1 www.abc.com ; www.123.com ; www.xyz.com ( Pool 1)

 

x.x.x.2 WebSrv_2 www.abc.com ; www.123.com ; www.xyz.com (Pool 2)

 

 

We have three health monitor abc.asp , 123.asp , xyz.asp , this health monitor prduces an output ( Receive string) depending on IIS & Database accordingly the pool becomes up and down.

 

 

Our requirement is any one of the website in a pool goes down , remaining 2 websites also should be marked down.

 

 

logic should be something like ....if (abc & 123 & xyz ) are OK then WebSrv_1 else WebSrv_2

 

 

let me know if you need any further details

 

 

thanks

 

 

You can do things like checking the number of pool members available before sending traffic to the pool with an iRule, but I don't think that you can check the availability of a downstream application status with an iRule.

 

 

The Pool can have numerous Health Checks applied to it and requirements on the number of health checks that must be successful in order to have the node marked up, but that would be an all or nothing.

 

 

I would suggest setting up a different pool and health check per site if you really want to be as accurate as possible.

Hi Michael,

 

 

Can you give samples of the iRule that you mentioned ?

 

 

I tried configuring multiple health checks on each pool , but it didn't work.

 

 

Thanks

 

 

Nathan / Michael --- Any clues or examples ??

 

 

Thanks in Advance.

 

 

Regards,

 

 

Prasad.

 

 

Hi Prasad,

 

 

You could create three custom monitors that check your logic for abc.asp, 123.asp and xyz.asp. If you hardcode the destination port in the monitors and assign each of the monitors to both pool members and set the pool to require all monitors succeed, if any one monitor fails the pool member will be marked down.

 

 

If that's not the exact logic you want, can you give example IP:ports and host header values for the different web apps and explain how you want the dependencies built?

 

 

Thanks, Aaron

Hi Aaron,

 

 

Thanks for the reply , I did exactly same thing for montoring , however it didn't work , the issue I faced is the health monitor only work for that particular website i.e "abc.asp" works for "www.abc.com" only , remaining two monitors i.e 123.asp & xyz.asp marks the node as down even if it is up.

 

 

Monitors are as below

 

 

for "ABC" - get http://abc.com/include/abc.asp - receive string "abc"

 

for "123" - get http://123.com/123.asp - receive string "123"

 

for "xyz" - get http://xyz.com/dir/xyz.asp - receive string "xyz"

 

 

Now if I apply all three monitors for one wesbite ..say for abc.com - only "ABC" monitor works remaining two i.e 123 & xyz marks the node as down even if it is up , same is for other website.

 

 

Can you help ?

 

 

Thanks & regards,

 

 

Prasad.

 

 

 

 

 

 

 

If you have all three sites running on both nodes in the pool, then why wouldn't all three monitors return true for both servers?

 

 

I think I'm a little bit confused by the requirements here. If you need to monitor 3 sites on each server, and all 3 are running on each server, then your above logic would work correctly, wouldn't it?

 

 

Colin

Hi Colin ,

 

 

Logic is simple and straightforward ..but it's not working :( !!

 

 

The reason that I am assuming are

 

 

1) Three websites are on three different IP's.

 

2) The Virtual directory for three web sites are different.

 

 

So when the health monitor tries to look for the .asp page other than it's own , it does not find the directory and gives an error 404 ( file or directory not found) and eventually it marks the node as down.

 

 

Is there any possibility that iRule will monitor the website independently and decides the pool ??

 

 

Thanks & regards,

 

 

Prasad.