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Forum Discussion

Brad_Otlin's avatar
Brad_Otlin
Ret. Employee
May 08, 2013
Solved

Reference an iRule variable in an HTML iFile response

I have a sorry page iRule that serves an html sorry page if no servers are left in the pool and serves another page if a 404 or 5xx is encountered. The 404/5xx portion of the irule tries each server...
application delivery
dev
devops
iRules
  • spark_86682's avatar
    spark_86682
    May 08, 2013
    I think the subst Tcl command is closest to what you want: 

    
HTTP::respond 200 content  [subst -nocommands -nobackslashes [ifile get error_html]]

    Very clean, and much safer than using eval.
Kevin_Stewart's avatar
Kevin_Stewart
Icon for Employee rankEmployee
May 08, 2013

It is possible, albeit a little tricky.

 


when HTTP_REQUEST {
    set http_host [HTTP::host]
    set http_uri [HTTP::uri]
    eval "set temp \"[string map {"\"" "\\\""} [ifile get down.html]]\""
    HTTP::respond 200 content $temp
}

 

You can also just do:

HTTP::respond 200 content [eval "set temp \"[string map {"\"" "\\\""} [ifile get down.html]]\""]

You can use local variables and commands (ie. [HTTP::host]) inside the HTML files as well. Essentially what you're doing is assigning the contents of the HTML file to a local variable, encapsulating the whole thing in quotation marks to make it one long string, replacing all of the internal quotation marks with escaped quotation marks, and then evaluating the new string to replace all of the inline variables and commands. You have to be careful of course that you don't have any TCL errors in your HTML, as that'll be a little less forgiving in the troubleshooting department. Also, if you have any other special characters in your HTML, like the square brackets, you'll need to escape them too.