Gzipped content being sent to HTTP/1.0 clients?

[Igor Sysoev]

On Mon, Aug 01, 2011 at 02:42:50PM +1200, Nicholas Sherlock wrote:
> Hi everyone,
> 
> I'm using gzip and proxy_cache together, proxying to an Apache backend.
> Some of my clients are complaining that they are getting gzipped content
> which their browser is displaying without un-gzipping it, presumably
> because they getting served gzipped content when their browser doesn't
> support it.
> 
> I noticed that HTTP/1.0 clients are getting served gzipped content even
> though gzip_http_version is set to 1.1. That should never happen, right?
> I guess it is because a 1.1 client requested it first, and it got
> cached? Here's the log of an HTTP/1.0 client (wget) grabbing the resource:
> 
> wget -d
> "http://www.chickensmoothie.com/Forum/style.php?id=9&lang=en&v=1312084157"
> 
> ---request begin---
> GET /Forum/style.php?id=9&lang=en&v=1312084157 HTTP/1.0
> User-Agent: Wget/1.12 (cygwin)
> Accept: */*
> Host:www.chickensmoothie.com
> Connection: Keep-Alive
> 
> ---response begin---
> HTTP/1.1 200 OK
> Server: nginx/1.0.4
> Date: Mon, 01 Aug 2011 00:23:27 GMT
> Content-Type: text/css; charset=UTF-8
> Connection: keep-alive
> X-Powered-By: PHP/5.3.5-1ubuntu7.2
> Expires: Wed, 09 Nov 2011 00:22:33 GMT
> Last-Modified: Sun, 31 Jul 2011 03:49:17 GMT
> Vary: Accept-Encoding
> Content-Encoding: gzip
> Content-Length: 15750
> 
> ---response end---
> 200 OK
> Registered socket 3 for persistent reuse.
> URI content encoding = `UTF-8'
> Length: 15750 (15K) [text/css]
> Saving to: `style.php at id=9&lang=en&v=1312084157.4'
> 
> 2011-08-01 12:22:35 (21.4 KB/s) -
> `style.php at id=9&lang=en&v=1312084157.4' saved [15750/15750]
> 
> 
> Note that the backend isn't sending a gzipped response to Nginx:
> 
> 
> wget --header="Host:www.chickensmoothie.com" -d
> "http://localhost:8080/Forum/style.php?id=9&lang=en&v=1312084157"
> 
> ---request begin---
> GET /Forum/style.php?id=9&lang=en&v=1312084157 HTTP/1.0
> User-Agent: Wget/1.12 (linux-gnu)
> Accept: */*
> Host:www.chickensmoothie.com
> Connection: Keep-Alive
> 
> ---response begin---
> HTTP/1.1 200 OK
> Date: Mon, 01 Aug 2011 00:32:28 GMT
> Server: Apache/2.2.17 (Ubuntu)
> X-Powered-By: PHP/5.3.5-1ubuntu7.2
> X-Accel-Expires: 600
> Expires: Wed, 09 Nov 2011 00:32:28 GMT
> Last-Modified: Sun, 31 Jul 2011 03:49:17 GMT
> Vary: Accept-Encoding
> Connection: close
> Content-Type: text/css; charset=UTF-8
> 
> ---response end---
> 200 OK
> Length: unspecified [text/css]
> Saving to: `style.php?id=9&lang=en&v=1312084157.5'
> 
> 2011-08-01 00:32:28 (377 MB/s) - `style.php?id=9&lang=en&v=1312084157.5'
> saved [78125]
> 
> 
> Here's my config details:
> 
> nginx: nginx version: nginx/1.0.4
> 
> gzip on;
> gzip_disable "MSIE [1-6]\.(?!.*SV1)";
> gzip_buffers 16 4k;
> gzip_types text/plain text/html text/css application/json
> application/x-javascript text/xml application/xml application/xml+rss
> text/javascript;
> gzip_vary on;
> gzip_http_version 1.1;
> 
> proxy_temp_path /caches/proxy_temp;
> proxy_cache_path /caches/nginx levels=1:2 keys_zone=one:50m inactive=3d
> max_size=10g;
> 
> server {
> 	listen 80 default;
> 	server_name _;
> 
> 	index index.php index.html index.htm;
> 
> 	location /Forum/style.php {
> 		proxy_passhttp://127.0.0.1:8080;
> 		proxy_redirect off;
> 		proxy_set_header X-Real-IP $remote_addr;
> 		proxy_set_header Host $host;
> 		proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
>
> 		proxy_read_timeout 600;
> 		proxy_intercept_errors on;
> 
> 		proxy_cache one;
> 		proxy_cache_key $host$request_uri;
> 		proxy_cache_valid 200 301 302 2000m;
> 		proxy_cache_use_stale error timeout invalid_header updating;
> 	}
> }
> 
> I've disabled the proxy_cache for the moment, which seems to fix this
> behaviour (HTTP/1.0 clients get a plain response, HTTP/1.1 clients who
> send an accept-encoding:gzip get a gzipped response).

Add
                proxy_set_header Accept-Encoding "";
to disable gzipping on backend.

or add a gzip flag in cache key:

map $http_accept_encoding  $gzip {
    default                "";
    ~gzip                  " gzip";
}

     proxy_cache_key "$host$request_uri$gzip";


-- 
Igor Sysoev