Friday, May 26, 2017

Hosted SITE-DOWN F5 style with IRules

When hosting web-sites, we have the means to craft  a "SIT-DOWN PAGE" to give feedback to the end-users that the site is down and the reason way.

It's good practice for providing a comfort page so the user would know the site is down versus hitting dry air. The site being down could be from a host of issues

  • planned maintenance
  • un-planned maintenance
  • serve-load
  • critical errors
  • code-application errors
  • etc..

Concept #1 is a hosted HTML PAGE via the F5 LTM


Concept#2  is to host a pool of ever-green servers that house the SITE_DOWN pages. Bigger application hosting outfits typical this method


Concept#3  is to host a server  node that houses the site down page


A hosted a data iFile and  that's call   out as required


Out of the above the pool and or node is the better method , since the administrators of the web server that hosts the site down can modify the content as required, If you set a NULL_POOL, you can always call up the "dummy" site and check the page. With a off-F5-LTM hosted site_down page, the  F5 engineer would not be tied up with managing Ifile or HTML respond content.

With the NULL_POOL defined, you can point your  browser at the will call up the hosted our  site_down for testing

Image result for SITE DOWN

And lastly, you could a simple site  http redirect or fallback statement, but be advise of  mistakes with bad 302 redirects or even worst redirect loops.

Finally the title of this post was specific with examples for using Irules. We have one more method that's even simpler.

By using a priority-group and with a node(s) set as the SITE_DOWN, you can apply that  node to your pools to host the site DOWN when all other nodes are down in that pool.

See this visio diagram where we have two priority groups and the last group with the server node "SSD" while be hit for the SiteDown page when !!!!! ALL OTHER NODES HAVE FAILED !!!!

Ken Felix

Ken Felix
NSE ( network security expert) and Route/Switching Engineer
kfelix  -----a----t---- socpuppets ---dot---com
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