Forum Discussion

jasona_40790's avatar
jasona_40790
Icon for Nimbostratus rankNimbostratus
Jun 14, 2012

need to rewrite HTTP 200 status code to HTTP 503

Hello,

 

 

I am performing website maintenance and need to bring down our website for a few hours. I will be

 

serving a friendly maintenance page during this time. However, when Google comes by during the

 

maintenance period this will present a problem for indexing. I am running BigIP version 10.2.3

 

 

Google strongly recommends that we return a 503 HTTP result code during the maintenance window:

 

http://googlewebmastercentral.blogs...anned-site-

 

downtime.htmlhttp://googlewebmastercentral.blogspot.com/2011/01/how-to-deal-with-planned-site-

 

downtime.html

 

There are similiar posts to mine in these forums, but none resolve what I am trying to do. I want to

 

serve a maintenance page from a pool in VIP and have the F5 rewrite the result code from a 200 to a 503.

 

I am able to apply the iRule to the VIP, however, it does not serve my maintenance page. This is my

 

iRule:

 

 

when HTTP_REQUEST {

 

HTTP::respond 503 noserver Retry-After: 10800

 

}

 

 

Thanks,

 

 

 

application delivery
dev
devops
iRules
  • Richard__Harlan's avatar
    Richard__Harlan
    Historic F5 Account
    Jun 14, 2012
    In your iRule you are sending a respond to the request so the LTM will not send the request to the pool. This pop up awhile ago to the iRule and did a small change so it should work in your setup.

     

     

    https://devcentral.f5.com/Community/GroupDetails/tabid/1082223/asg/39/aft/5814/showtab/groupforums/Default.aspx

     

     

    when HTTP_REQUEST_SEND {

     

    TCP::collect 12

     

    }

     

    when SERVER_DATA {

     

    if {[findstr [TCP::payload 12] "200"] == "200"} {

     

    TCP::payload replace 9 3 "503"

     

    }

     

    }
  • hooleylist's avatar
    hooleylist
    Icon for Cirrostratus rankCirrostratus
    Jun 14, 2012
    Hi Jason,

    Do you see any errors in /var/log/ltm when you test that iRule? Are there other iRules or HTTP profile config options that might be sending a redirect? If so, you could disable all other iRules when you're using the maintenance iRule using event disable all: 

    
 https://devcentral.f5.com/wiki/iRules.event.ashx
when HTTP_REQUEST {
   HTTP::respond 503 noserver Retry-After: 10800
   event disable all
}

    Aaron
  • hooleylist's avatar
    hooleylist
    Icon for Cirrostratus rankCirrostratus
    Jun 14, 2012
    Richard's right and has a good example. I missed that you wanted to just rewrite the pool member's status code.

     

     

    There's an existing Request For Enhancement for rewriting the status code using HTTP::status $new_status_code:

     

     

    BZ385613 RFE: Make HTTP::status iRule command support writing data

     

     

    You can open a case with F5 Support to add your request to the RFE and raise its visibility.

     

     

    Aaron
  • jasona_40790's avatar
    jasona_40790
    Icon for Nimbostratus rankNimbostratus
    Jun 14, 2012
    Thanks much, that worked. I will also need to set the 503 'Retry-After header' with something similiar to this:

     

     

    Retry-After: Fri, 15 Jun 2012 13:00:00 GMT

     

     

     

    Where would I put this 'Retry-After header' in the example you gave me.

     

     

    Thanks,

     

    Jason
  • Richard__Harlan's avatar
    Richard__Harlan
    Historic F5 Account
    Jun 14, 2012
    In the HTTP_REQUEST_SEND you can add the header with the following command

     

     

    if { [HTTP::header exists "Retry-After"] } {

     

    HTTP::header replace Retry-After 10800

     

    } else {

     

    HTTP::header insert Retry-After: 10800

     

    }
  • jasona_40790's avatar
    jasona_40790
    Icon for Nimbostratus rankNimbostratus
    Jun 14, 2012
    Thanks Richard,

     

     

    Well, I added the 'Retry-After' code to my iRule and, while the iRule syntax accepted it, the maintenance page in the VIP is not accessible. I've posted my entire iRule. If I put the 'Retry-After' code anywhere else in the HTTP_REQUEST_SEND section, the iRule syntax will not accept it.

     

     

     

    when HTTP_REQUEST_SEND {

     

    if { [HTTP::header exists "Retry-After"] } {

     

    HTTP::header replace Retry-After 10800

     

    } else {

     

    HTTP::header insert Retry-After: 10800

     

    }

     

    TCP::collect 12

     

    }

     

    when SERVER_DATA {

     

    if {[findstr [TCP::payload 12] "200"] == "200"} {

     

    TCP::payload replace 9 3 "503"

     

    }

     

    }
  • Richard__Harlan's avatar
    Richard__Harlan
    Historic F5 Account
    Jun 14, 2012
    Can you post the error in /var/log/ltm. Most likely I over looked a syntex error whihc will cause the LTM to reset the connection and not display the page.
  • jasona_40790's avatar
    jasona_40790
    Icon for Nimbostratus rankNimbostratus
    Jun 14, 2012
    TCL error: iRule-Downtime503 - Illegal argument. Can't execute in the current context. (line 1) invoked from within "HTTP::header exists "Retry-After""

     

    Jun 14 16:04:18 local/tmm err tmm[7807]: 01220001:3: TCL error: iRule-Downtime503 - Illegal argument. Can't execute in the curre nt context. (line 1) invoked from within "HTTP::header exists "Retry-After""

     

  • Richard__Harlan's avatar
    Richard__Harlan
    Historic F5 Account
    Jun 15, 2012
    Ok it does not like the HTTP::header exists

     

     

    I read through the WIKI and it looks like that is redundant all you have to run is the following

     

     

    HTTP::header replace Retry-After: 10800

     

     

    if the header is not there it will add if it is then it will update.

     

     

    Sorry about that.
  • jasona_40790's avatar
    jasona_40790
    Icon for Nimbostratus rankNimbostratus
    Jun 15, 2012
    Richard,

     

    Still not working. Here is the /var/log/ltm:

     

     

    Jun 14 17:18:56 local/tmm1 err tmm1[7808]: 01220001:3: TCL error: iRule-Downtime503 - Illegal argument. Can't execute in the current context. (line 1) invoked from within "HTTP::header replace Retry-After: 10800"

     

     

     

    Here is the iRule:

     

    when HTTP_REQUEST_SEND {

     

    HTTP::header replace Retry-After: 10800

     

    TCP::collect 12

     

     

    }

     

    when SERVER_DATA {

     

    if {[findstr [TCP::payload 12] "200"] == "200"} {

     

    TCP::payload replace 9 3 "503"

     

    }

     

    }