problem summary:

php5-fastcgi works with nginx but doesn't work with nginx+varnish (502 Bad Gateway)

does anyone have a suggestion of what I could change to get varnish working ?

problem details:

This is my configuration:

(listening 80) nginx (requesting 8181) ==> (listening 8181) varnish ==> (listening 9090) php5-fastcgi

/etc/nginx/conf.d/mydomain.com

server {
  listen 80;
  server_name mydomain.com;
  index index.html index.htm index.php;
  keepalive_timeout  30;
  root /var/www/assets;
  location = /favicon.ico {
    log_not_found off;
    access_log off;
  }
  location ~\.php$ {
    root /var/www/api;
    add_header Access-Control-Allow-Origin *;
    fastcgi_pass 127.0.0.1:8181;
    include fastcgi_params;
    fastcgi_index index.php;
    fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
  }
  location ~ ^/(api|wp) {
    root /var/www/api;
    try_files $uri $uri/ /index.php?q=$uri&$args;
  }
}

/etc/default/varnish

START=yes
NFILES=131072
MEMLOCK=82000
DAEMON_OPTS="-a :8181 \
             -T localhost:6082 \
             -f /etc/varnish/default.vcl \
             -S /etc/varnish/secret \
             -s malloc,256M"

/etc/varnish/default.vlc

backend default {
    .host = "127.0.0.1";
    .port = "9090";
}
sub vcl_recv {
    set req.backend = default;
    if (!(req.url ~ "wp-(login|admin)")) {
            unset req.http.cookie;
    }
    return(lookup);
}
sub vcl_miss {
    return(fetch);
}
sub vcl_hit {
    return(deliver);
}
sub vcl_fetch {
    if (!(req.url ~ "wp-(login|admin)")) {
            unset beresp.http.set-cookie;
    }
    set beresp.ttl = 24h;
    set beresp.http.X-Cacheable = "YES";
    unset beresp.http.Vary;
    return(deliver);
}
sub vcl_deliver {
    return(deliver);
}

/usr/bin/php5-fastcgi-p

#!/bin/bash
FASTCGI_USER=user
FASTCGI_GROUP=www-data
PORT=9090
ADDRESS=127.0.0.1
PIDFILE=/var/run/php5-fastcgi.pid
CHILDREN=4
PHP5=/usr/bin/php5-cgi

/usr/bin/spawn-fcgi -a $ADDRESS -p $PORT -P $PIDFILE -C $CHILDREN -u $FASTCGI_USER -g $FASTCGI_GROUP -f $PHP5

(on ubuntu 10.04 lucid lynx)

This setup doesn't currently work (502 Bad Gateway).

I also get a couple messages in varnishlog when I'm making my requests

 0 CLI          - Wr 200 19 PONG 1380029665 1.0
 11 SessionOpen  c 127.0.0.1 42489 :8181
 11 Debug        c herding
 11 SessionClose c no request
 11 StatSess     c 127.0.0.1 42489 0 1 0 0 0 0 0 0
 0 CLI          - Rd ping
 0 CLI          - Wr 200 19 PONG 1380029668 1.0
 0 CLI          - Rd ping

so I tried another config where nginx goes around varnish, and It works like a charms.

(listen on 80 )nginx ==> (listen on 9090) php5-fastcgi

Usually people suggest it's spawn-fcgi 's fault but I think it's rather in varnish's config

(I'm working on Ubuntu 10.04 so the option of using php-fpm is not available.)

here is what I get with netstat-nlp

tcp        0      0 0.0.0.0:8181            0.0.0.0:*               LISTEN      20886/varnishd  
tcp        0      0 127.0.0.1:9090          0.0.0.0:*               LISTEN      20989/php5-cgi  
tcp        0      0 127.0.0.1:6082          0.0.0.0:*               LISTEN      20885/varnishd  
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN      1478/nginx.conf 
tcp6       0      0 :::8181                 :::*                    LISTEN      20886/varnishd