Is it possible to set filters by browser?

[Vidyut]

If, for example, I want to not combine scripts for spdy/http2 enabled browsers and combine for the rest, how do I do it?

Vidyut

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[Jeff Kaufman]

In the upcoming 1.10 release you can use nginx script variables with
the EnableFilters/DisableFilters commands. This would look like this:

http {
...
pagespeed ProcessScriptVariables on;
location / {
set $disablefilters "";

if ($spdy) {
set $disablefilters "list,of,filters,to,disable";
}

pagespeed DisableFilters $disablefilters;
}
}

If you'd like to try this out now, it's a tiny patch:
https://github.com/pagespeed/ngx_pagespeed/commit/afd0f01686e1f06bfff86efd06324d54b2244f9a

See https://developers.google.com/speed/pagespeed/module/domains#LoadFromFileScriptVariables
for more on ProcessScriptVariables.

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[Hans van Eijsden]

That's great new Jeff. Thanks, I'm looking forward to it.

One thing though: the first thing everybody learns about nginx is "if = evil": https://www.nginx.com/resources/wiki/start/topics/depth/ifisevil/ but in the example above, there's "if" in a location block.

Is there a way to do it without "if"?

Hans

Op zondag 1 november 2015 19:14:32 UTC+1 schreef Jeff Kaufman:

> email to ngx-pagespeed-discuss+unsub...@googlegroups.com.

[Otto van der Schaaf]

On Sun, Nov 1, 2015 at 11:39 PM, Hans van Eijsden <hans...@gmail.com> wrote:

One thing though: the first thing everybody learns about nginx is "if = evil": https://www.nginx.com/resources/wiki/start/topics/depth/ifisevil/ but in the example above, there's "if" in a location block.

Is there a way to do it without "if"?

Using "if" just to set a variable in a server{} block should work fine (and I think it is also a good place as that also is where protocols are configured). 

So for example, you could configure something like this:

http {
pagespeed ProcessScriptVariables on;
server {
    set $spdy_disable "";

    if ($spdy) {
       set $spdy_disable "combine_css,combine_javascript";
    }
    pagespeed DisableFilters "$spdy_disable";
}
}

In location{} blocks, "if" gets tricky, but it does behave consistently. 

So if a configuration depending on if-in-location works for a single request, it should work for all of them.

Otto

[Jeff Kaufman]

I realized I don't have draft doc for this feature for the 1.10
release. I've started that doc now, which then reminded me that we
don't support disabling ShardDomain. So I'm adding that too.

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[Jeff Kaufman]

The configuration I'm planning to recommend for people running http2/spdy is:

http {
pagespeed ProcessScriptVariables on;
server {

set $disable_filters "";
set $domain_shards "shard1,shard2,shard3..."

if ($http2) {
set $disable_filters "combine_css,combine_javascript";
set $domain_shards "";
}
pagespeed DisableFilters "$disable_filters";
pagespeed ShardDomain domain_to_shard "$domain_shards";
}
}

The ShardDomain portion of this needs a psol update, though.

[Vidyut]

Thanks! This is useful. Will play with it a bit when I get time.

I agree IfIsEvil but there should be a way of setting it in another manner to avoid the if. Will figure it out and share back if useful. Map could come in handy.... or something.

Vidyut

[Jeff Kaufman]

I really don't think we should be trying to avoid the use of "if"
here. Setting a variable in an "if" statement in a server block is
one of the safe ways to use it.