Forum Discussion
adalan_1411
Nimbostratus
NimbostratusHTTP Profile :: Vary Header Help
Not sure if this is the correct place for this, but I'm noticing what I would consider and abnormality in the way the VARY header is working. It seems to be adding a User-Agent component the vary header which I would like to remove:
With "vary header" checked under compression on HTTP profile:
----------------------------------------------------------
HTTP/1.x 200 OK
Date: Mon, 17 Aug 2009 13:06:39 GMT
Edge-control: !no-store
Content-Type: text/html
Expires: Tue, 18 Aug 2009 13:06:38 GMT
Cache-Control: max-age=86400,private
Vary: Accept-Encoding, User-Agent
Content-Encoding: gzip
Connection: close
----------------------------------------------------------
With "vary header" unchecked under compression on HTTP profile:
----------------------------------------------------------
HTTP/1.x 200 OK
Date: Mon, 17 Aug 2009 13:08:04 GMT
Edge-control: !no-store
Content-Type: text/html
Expires: Tue, 18 Aug 2009 13:08:04 GMT
Cache-Control: max-age=86400,private
Content-Encoding: gzip
Connection: close
----------------------------------------------------------
Is there a way to remove just the User-Agent portion?
hoolioCirrostratus
I'm not too familiar with the Vary header and whether there is a good way to address this in the configuration. But if you want to remove everything including and after the first comma, you could use scan:
scan everything not a comma into precomma and the rest into ignore
scan [HTTP::header Vary] {%[^,]%s} precomma ignore
Update the Vary header value with the scan output
HTTP::header replace Vary $precomma
Else, getfield would allow you to do this without the intermediate variables:
Update the Vary header value with first field of the Vary header value, delimited by commas
HTTP::header replace Vary [getfield [HTTP::header Vary] "," 1]
Aaron
adalan_1411It seems like a lot of processing, I'd think there would be some setting to change the vary header that it's sending out. I just can't find it.- dennypayne
Employee
Vary headers allow you to change some element of a response (in this case, compression) based on a varying element of a request. Different browsers handle compression in different ways, so you typically want to vary on User-Agent to accommodate this. I believe that LTM has some built-in optimizations for compression if it is allowed to vary on User-Agent.
I'm sure you have your reasons for wanting to remove this (and I can't think of anything at the moment to improve on Aaron's solution), but that's why it is there.
Denny 
sidiovI want to resurrect this and ask if the OP ever got it working with just accept-encoding? I need this for our CDN network which only works with accept-encoding, and irules seem to have no effect on headers generated by the Load balancer, so I cant replace or insert new values.- If you need responses that the BIG-IP compresses to not Vary based on User-Agent, then you should disable the "browser workarounds" option in the compression profile, and make sure that compression to HTTP/1.0 clients is enabled.
