Nginx + fastCGI = 502 bad gateway

[dekar411]

Greetings

I'm trying to setup Nagios web interface to work with Nginx, but I'm
showed a 502 Bad Gateway just after login.

This is the nginx log (10.82.1.158 is the server and 10.82.1.106 is the
client): 

==> /var/log/nginx/access.https.log <== 
10.82.1.106 - swissmsnagios [02/Aug/2011:17:19:15 +0200] "GET
/cgi-bin/nagios3/tac.cgi HTTP/1.1" 502 173
"https://10.82.1.158/nagios3/side.html" "Mozilla/5.0 (X11; Linux x86_64)
AppleWebKit/534.30 (KHTML, like Gecko) Ubuntu/11.04
Chromium/12.0.742.112 Chrome/12.0.742.112 Safari/534.30" 

==> /var/log/nginx/error.https.log <== 
2011/08/02 17:19:15 [warn] 1161#0: *57 using uninitialized "script"
variable, client: 10.82.1.106, server: vb5, request: "GET
/cgi-bin/nagios3/tac.cgi HTTP/1.1", host: "10.82.1.158", referrer:
"https://10.82.1.158/nagios3/side.html" 
2011/08/02 17:19:15 [warn] 1161#0: *57 using uninitialized "path_info"
variable, client: 10.82.1.106, server: vb5, request: "GET
/cgi-bin/nagios3/tac.cgi HTTP/1.1", host: "10.82.1.158", referrer:
"https://10.82.1.158/nagios3/side.html" 
2011/08/02 17:19:15 [error] 1161#0: *57 connect() failed (111:
Connection refused) while connecting to upstream, client: 10.82.1.106,
server: vb5, request: "GET /cgi-bin/nagios3/tac.cgi HTTP/1.1", upstream:
"fastcgi://127.0.0.1:49233", host: "10.82.1.158", referrer:
"https://10.82.1.158/nagios3/side.html" 

Relevant entry at Nginx configuration: 

    location ~ ^/cgi-bin/nagios3($|/.*) { 
        alias /usr/lib/cgi-bin/nagios3$1; 

        fastcgi_pass 127.0.0.1:49233; 
        fastcgi_param SCRIPT_FILENAME
$document_root$fastcgi_script_name; 

        auth_basic "Nagios Access"; 
        auth_basic_user_file /etc/nagios3/htpasswd.users; 

        fastcgi_param AUTH_USER $remote_user; 
        fastcgi_param REMOTE_USER $remote_user; 

        fastcgi_param QUERY_STRING $query_string; 
        fastcgi_param REQUEST_METHOD $request_method; 
        fastcgi_param CONTENT_TYPE $content_type; 
        fastcgi_param CONTENT_LENGTH $content_length; 
        fastcgi_param SCRIPT_NAME $script; 
        fastcgi_param PATH_INFO $path_info; 
        fastcgi_param REQUEST_URI $request_uri; 
        fastcgi_param DOCUMENT_URI $document_uri; 
        fastcgi_param DOCUMENT_ROOT $document_root; 
        fastcgi_param SERVER_PROTOCOL HTTP/1.0; 
        fastcgi_param GATEWAY_INTERFACE CGI/1.1; 
        fastcgi_param SERVER_SOFTWARE nginx; 
        fastcgi_param REMOTE_ADDR $remote_addr; 
        fastcgi_param REMOTE_PORT $remote_port; 
        fastcgi_param SERVER_ADDR $server_addr; 
        fastcgi_param SERVER_PORT $server_port; 
        fastcgi_param SERVER_NAME $server_name; 
    } 

Things tested:

- Comment the alias sentence
(http://forum.nginx.org/read.php?2,212501,212501)
- Switch from "fastcgi_pass 127.0.0.1:49233;" to "fastcgi_pass
127.0.0.1:3590;" (as netstat showed)

Additional info:

$ nginx -V
nginx version: nginx/0.7.65
TLS SNI support enabled
configure arguments: --conf-path=/etc/nginx/nginx.conf
--error-log-path=/var/log/nginx/error.log --pid-path=/var/run/nginx.pid
--lock-path=/var/lock/nginx.lock
--http-log-path=/var/log/nginx/access.log
--http-client-body-temp-path=/var/lib/nginx/body
--http-proxy-temp-path=/var/lib/nginx/proxy
--http-fastcgi-temp-path=/var/lib/nginx/fastcgi --with-debug
--with-http_stub_status_module --with-http_flv_module
--with-http_ssl_module --with-http_dav_module
--with-http_gzip_static_module --with-http_realip_module --with-mail
--with-mail_ssl_module --with-ipv6
--add-module=/build/buildd/nginx-0.7.65/modules/nginx-upstream-fair

$ cat /etc/lsb-release 
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=10.04
DISTRIB_CODENAME=lucid
DISTRIB_DESCRIPTION="Ubuntu 10.04.3 LTS"

$ dpkg -l | grep cgi
ii  fcgiwrap                                         1.0-1              
              simple server to run CGI applications over F
ii  libfcgi0ldbl                                     2.4.0-8            
              Shared library of FastCGI
ii  nagios3-cgi                                      3.2.0-4ubuntu2.2   
              cgi files for nagios3
ii  php5-cgi                                         5.3.2-1ubuntu4.9   
              server-side, HTML-embedded scripting languag
ii  spawn-fcgi                                       1.6.3-1            
              A fastcgi process spawner

$ sudo netstat -anp | grep cgi
tcp        0      0 127.0.0.1:9001          0.0.0.0:*              
LISTEN      686/php-cgi     
tcp        0      0 127.0.0.1:9002          0.0.0.0:*              
LISTEN      692/php-cgi     
unix  2      [ ACC ]     STREAM     LISTENING     3590     738/fcgiwrap 
      /var/run/fcgiwrap.socket

Thanks in advance.

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,213277,213277#msg-213277