Letsgetdugg

I have dumped varnish as our primary cache due to multiple failures of service. I have tried to make it work but varnish kept insisting on producing 503 XID backend failures on perfectly healthy backends. I have tried doing all types of crazy configuration hacks such as forcing varnish to retry backends via a round-robin director. It did not work out all too well since the round trip added latency when varnish had to re-fetch the document multiple times. The final straw that broke the camel’s back was when varnish configured for a 256mb malloc store grew to an astonishing size of 780mb+ RSS.

I have switched to squid-3 and so far it has been stable and fast. I will later post a matching squid configuration to the one below that does the same thing.

Squid-3 will require this patch for it to compile on Solaris.

Varnish on Solaris is a dud.

List of failures

1. Producing 503 responses for perfectly healthy backends. Backend never even gets contacted.
2. Growing to a crazy size when using the malloc implementation.
3. Segfaulting every hour on the hour with the newest trunk r4080+

Here is the configuration I have used. Feel free to use it if varnish works for you.

#
# This is a basic VCL configuration file for varnish.  See the vcl(7)
# man page for details on VCL syntax and semantics.
#
# $Id: default.vcl 1818 2007-08-09 12:12:12Z des $
#

# Default backend definition.  Set this to point to your content
# server.

 # my wonderful re-try hack, that kinda works.
 director www_dir round-robin {
     { .backend = { .connect_timeout = 2s; .host="127.0.0.1"; .port="8001"; }  }
     { .backend = { .connect_timeout = 2s; .host="127.0.0.1"; .port="8001"; }  }
     { .backend = { .connect_timeout = 2s; .host="127.0.0.1"; .port="8001"; }  }
     { .backend = { .connect_timeout = 2s; .host="127.0.0.1"; .port="8001"; }  }
 }

#backend default { .host = "127.0.0.1"; .port = "8089"; .connect_timeout = 2s; }

sub vcl_recv {
 remove req.http.X-Forwarded-For;
 set req.http.X-Forwarded-For = client.ip;
 set req.grace = 2m;

    if (req.http.Accept-Encoding) {
        if (req.url ~ "\.(jpeg|jpg|png|gif|gz|tgz|bz2|tbz|mp3|ogg|ico|swf|flv|dmg)") {
            # No point in compressing these
            remove req.http.Accept-Encoding;
        } elsif (req.http.Accept-Encoding ~ "gzip") {
            set req.http.Accept-Encoding = "gzip";
        } elsif (req.http.Accept-Encoding ~ "deflate") {
            set req.http.Accept-Encoding = "deflate";
        } else {
            # unkown algorithm
            remove req.http.Accept-Encoding;
        }
    }

# don't trust MSIE6
# if (req.http.user-agent ~ "MSIE [1-6]\.") {
#     remove req.http.Accept-Encoding;
# }

 if (req.http.host == "jira.fabulously40.com") {
   pipe;
 }

 if (req.request == "GET" || req.request == "HEAD") {
	if ( req.url ~ "\.(xml|gif|jpg|swf|css|png|jpeg|tiff|tif|svg|ico|pdf|ico|swf)") {
		remove req.http.cookie;
		lookup;
	}
	# avoid caching jsps
	if ( req.url ~ "\.js([^p]|$)" ) {
		remove req.http.cookie;
		lookup;
	}
 }

 # don't bother caching large files
 if(req.url ~ "\.(mp3|flv|mov|mp4|mpg|mpeg|avi|dmg)") {
     pipe;
 }

 if (req.request != "GET" && req.request != "HEAD") {
     pipe;
 }

 if (req.request == "POST") {
     pipe;
 }

 if (req.http.Expect || req.http.Authorization || req.http.Authenticate || req.http.WWW-Authenticate) {
    pipe;
 }

 # pipe pages with these cookies set
 if (req.http.cookie && req.http.cookie ~ "_.*_session=") {
     pipe;
 }
 if (req.http.cookie && req.http.cookie ~ "JSESSIONID=") {
     pipe;
 }
 if (req.http.cookie && req.http.cookie ~ "PHPSESSID=") {
     pipe;
 }
 if (req.http.cookie && req.http.cookie ~ "wordpress_logged_in") {
     pipe;
 }

 lookup;
}

sub vcl_error {
	# retry on errors
    if (obj.status == 503) {
        if ( req.restarts < 12 ) {
             restart;
         }
     }
}

sub vcl_fetch {

	# don't cache when these cookies are in place
	if(beresp.http.Location || beresp.http.WWW-Authenticate) {
	    pass;
	}
	if(beresp.http.cookie && beresp.http.cookie ~ "JSESSIONID=") {
	    pass;
	}
	if(beresp.http.Set-Cookie && beresp.http.Set-Cookie ~ "JSESSIONID=") {
	    pass;
	}
	if(beresp.http.cookie && beresp.http.cookie ~ "_.*_session=") {
	    pass;
	}
	if(beresp.http.Set-Cookie && beresp.http.Set-Cookie ~ "_.*_session=") {
	    pass;
	}
	if(beresp.http.cookie && beresp.http.cookie ~ "PHPSESSID=") {
	    pass;
	}
	if(beresp.http.Set-Cookie && beresp.http.Set-Cookie ~ "PHPSESSID=") {
	    pass;
	}
	if(beresp.http.cookie && beresp.http.cookie ~ "wordpress_logged_in") {
	    pass;
	}
	if(beresp.http.Set-Cookie && beresp.http.Set-Cookie ~ "wordpress_logged_in") {
	    pass;
	}
	if(beresp.http.Cache-Control && beresp.http.Cache-Control ~ "no-cache") {
	    pass;
	}
	if(beresp.http.Pragma && beresp.http.Pragma ~ "no-cache") {
	    pass;
	}

# avoid defaults since we *want* pages cached with cookies
#	if (!beresp.cacheable) {
#	    pass;
#	}
#	if (beresp.http.Set-Cookie) {
#		pass;
#	}

	#cache for 30 minutes..
	if((beresp.http.Cache-Control !~ "max-age" || beresp.http.Cache-Control !~ "s-maxage") && beresp.ttl < 1800s) {
		set beresp.ttl = 1800s;
	}
	set beresp.grace = 2m;

	# anonymous users get 10 min delay
	if(beresp.http.Content-Type && beresp.http.Content-Type ~ "html" && (beresp.http.Cache-Control !~ "max-age" ||  beresp.http.Cache-Control !~ "s-maxage")) {
	    set beresp.ttl = 600s;
	}

	# remove server affinity cookie from cached pages.
	if(beresp.http.Set-Cookie && beresp.http.Set-Cookie ~ "X-SERVERID=") {
	    remove beresp.http.Set-Cookie;
	}
	if(beresp.http.Set-Cookie && beresp.http.Set-Cookie ~ "SERVERID=") {
	    remove beresp.http.Set-Cookie;
	}
	if(beresp.http.X-Backend) {
	    remove beresp.http.X-Backend;
	}

	deliver;
}