irule replace and modify uri and response

[Juan_Carlos_Rom]

Hello everyone,

I have a problem with the irule that I've develop to the response from the server.

To put them in context the user access to the app with three different uri:

1. https://example.com/ris1

2.https://example.com/ris2

3.https://example.com/ris3

There are three different pools with two pool members for each.

When the servers receives the resquests is more like:

first sever http://example.com/Novaris with the same name for the path.

My irule is like this:

when HTTP_REQUEST {

STREAM::disable
# Check the requested path (set to lowercase)
# -glob: allow string pattern matching
switch -glob -- [string tolower [HTTP::uri]] {
"/ris1" {
log local0. "Matched pool 1 paths for [HTTP::uri]"
set uri [ string map -nocase { "/ris1" "/Novaris"} [HTTP::uri] ]
HTTP::uri $uri
HTTP::header remove "Accept-Encoding"
pool P1
}
"/ris2" {
log local0. "Matched pool 1 paths for [HTTP::uri]"
set uri [ string map -nocase { "/ris2" "/Novaris"} [HTTP::uri] ]
HTTP::uri $uri
HTTP::header remove "Accept-Encoding"
pool P2
}
"/ris3" {
log local0. "Matched pool 1 paths for [HTTP::uri]"
set uri [ string map -nocase { "/ris3" "/Novaris"} [HTTP::uri] ]
HTTP::uri $uri
HTTP::header remove "Accept-Encoding"
pool P3
}
default {
log local0. "Hit default for [HTTP::uri]"
HTTP::header remove "Accept-Encoding"
persist cookie insert "Redimed"
pool Pool_demobank
}
}
}

when HTTP_RESPONSE {
STREAM::disable
if {([HTTP::status] == 200) && ([HTTP::header value Content-Type] contains "text") } {
STREAM::expression { @http@https@ @/Novaris@/ris1@ @/Novaris@/ris2@ @/Novaris@/ris3@ }
STREAM::enable
}
}

My problem is in the response.

When the server response because the payload don't show the image so I fix with the stream:expression but with the other two not. Because the path have the same name there is another way to map this problem o I need to explain to the development team to modify the name of the path with each pool.

Thank you if anyone can help me.

[candc · Accepted solution]

If I understand you correctly, you need to alter the stream expression in your HTTP_RESPONSE event, based either on the pool that was selected or the URI you received, during the HTTP_REQUEST event. 

Note that you may need to capture that in a variable in the HTTP_REQUEST event, and check the variable in the HTTP_RESPONSE event, because you might only be able to use certain API functions inside certain events.

Something like:

when HTTP_REQUEST {
  set orig_uri [HTTP::uri]
  # the rest of your logic
}
when HTTP_RESPONSE {
  STREAM::disable
  if {([HTTP::status] == 200) && ([HTTP::header value Content-Type] contains "text") } {
    switch -glob -- [string tolower $orig_uri] {
      "/ris1*" {
        STREAM::expression {@http:@https:@ @/[Nn]ovaris@/ris1@}
      }
      "/ris2*" {
        STREAM::expression {@http:@https:@ @/[Nn]ovaris@/ris2@}
      }
      "/ris3*" {
        STREAM::expression {@http:@https:@ @/[Nn]ovaris@/ris3@}
      }
    }
    STREAM::enable
  }
}

(There are other optimisations that might shorten this, but you should get the gist)

Note that I have also changed the expression for your http/https rewrite to http:/https: (note the colon), so that any https:// URI returned by the downstream server is not rewritten to httpss://.

You may also need to handle a case-sensitive response back from the downstream server (I presume you would need to rewrite /Novaris or /novaris for instance).  To that end, you may need to make your stream search expression something like...

@/[Nn][Oo][Vv][Aa][Rr][Ii][Ss]@/ris1@

...so it handles upper- and lower-case.

[StephanManthey]

Hi @Juan_Carlos_Rom , are you using a OneConnect profile (to be assigned in the virtual server acceleration settings)?

As you are trying to "demultiplex" requests coming in through a clientside KeepAlive connection, it will be necessary to use OneConnect. Otherwise the incoming connection will be balanced to a pool according to your iRule logic and just stick there. With OneConnect enabled each incoming request will be handled individually.

I recommend to use a new OneConnect profile with a host mask of 32 bits (IPv4) or 128 bits (IPv6).

[Juan_Carlos_Rom]

Hi Stephan,

In this momento in the virtual server, I don't apply any acceleration settings.

Tomorrow, I'm going to test again with the profile oneConnect with the mask of 32 bits for ipv4.

Then, I will replay the outcome.

And thank you,  for your suggestion.

[candc · Accepted solution]

If I understand you correctly, you need to alter the stream expression in your HTTP_RESPONSE event, based either on the pool that was selected or the URI you received, during the HTTP_REQUEST event. 

Note that you may need to capture that in a variable in the HTTP_REQUEST event, and check the variable in the HTTP_RESPONSE event, because you might only be able to use certain API functions inside certain events.

Something like:

when HTTP_REQUEST {
  set orig_uri [HTTP::uri]
  # the rest of your logic
}
when HTTP_RESPONSE {
  STREAM::disable
  if {([HTTP::status] == 200) && ([HTTP::header value Content-Type] contains "text") } {
    switch -glob -- [string tolower $orig_uri] {
      "/ris1*" {
        STREAM::expression {@http:@https:@ @/[Nn]ovaris@/ris1@}
      }
      "/ris2*" {
        STREAM::expression {@http:@https:@ @/[Nn]ovaris@/ris2@}
      }
      "/ris3*" {
        STREAM::expression {@http:@https:@ @/[Nn]ovaris@/ris3@}
      }
    }
    STREAM::enable
  }
}

(There are other optimisations that might shorten this, but you should get the gist)

Note that I have also changed the expression for your http/https rewrite to http:/https: (note the colon), so that any https:// URI returned by the downstream server is not rewritten to httpss://.

You may also need to handle a case-sensitive response back from the downstream server (I presume you would need to rewrite /Novaris or /novaris for instance).  To that end, you may need to make your stream search expression something like...

@/[Nn][Oo][Vv][Aa][Rr][Ii][Ss]@/ris1@

...so it handles upper- and lower-case.

[Enes_Afsin_Al · Accepted solution]

Hi,

If the stream expression string starts or ends with space, it won't work.
It looks neater with space, but it shouldn't. 🙂

# This will work
STREAM::expression {@IE@Apache@ @Windows@Linux@}

# and this will work
STREAM::expression [list "@IE@Apache" "@Windows@Linux@"]

# but this will NOT work-- notice the space between the '{' and the '@'
STREAM::expression { @IE@Apache@ @Windows@Linux@ }

REF: https://clouddocs.f5.com/api/irules/STREAM__expression.html

[candc]

Great point -- I have updated my example above.

I do love TCL but, coming form other languages, their decision to use braces as a string-literal delimeter always catches me out!

[Juan_Carlos_Rom]

Thank you for your time. I fix the problem.