Ryfujk

I'm experiencing 502 Gateway errors when accessing a PHP file in a directory (http://example.com/dev/index.php). The logs simply says this:

2011/09/30 23:47:54 [error] 31160#0: *35 connect() failed (111: Connection refused) while connecting to upstream, client: xx.xx.xx.xx, server: domain.com, request: "GET /dev/ HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "domain.com"

I've never experienced this before. What is the solution for this type of 502 Gateway error?

This is the nginx.conf:

user www-data;

worker_processes 4;

pid /var/run/nginx.pid;



events {

    worker_connections 768;

    # multi_accept on;

}



http {



    ##

    # Basic Settings

    ##



    sendfile on;

    tcp_nopush on;

    tcp_nodelay on;

    keepalive_timeout 65;

    types_hash_max_size 2048;

    # server_tokens off;



    # server_names_hash_bucket_size 64;

    # server_name_in_redirect off;



    include /etc/nginx/mime.types;

    default_type application/octet-stream;



    ##

    # Logging Settings

    ##



    access_log /var/log/nginx/access.log;

    error_log /var/log/nginx/error.log;



    ##

    # Gzip Settings

    ##



    gzip on;

    gzip_disable "msie6";



    # gzip_vary on;

    # gzip_proxied any;

    # gzip_comp_level 6;

    # gzip_buffers 16 8k;

    # gzip_http_version 1.1;

    # gzip_types text/plain text/css application/json application/x-javascript text/xml application/xml application/xml+rss text/javascript;



    ##

    # Virtual Host Configs

    ##



    include /etc/nginx/conf.d/*.conf;

    include /etc/nginx/sites-enabled/*;

}

It sounds like you haven't started and configured the backend for Nginx. Start php-fpm and add the following to nginx.conf, in the http context:

server {

    listen 127.0.0.1;

    server_name localhost;



    error_log /var/log/nginx/localhost.error_log info;



    root /var/www/localhost/htdocs;



    location ~ .php$ {

        fastcgi_pass 127.0.0.1:9000;

        include /etc/nginx/conf.d/*.conf;

        include /etc/nginx/sites-enabled/*;



        fastcgi_intercept_errors        on;

        error_page 404 /error/404.php;

    }

}

This answer is only for those who get an error like this:

connect() failed (111: Connection refused) while connecting to upstream, client ....
fastcgi://[::1]:9000

Rewrite your nginx config to use ip, not dns. For instance, 127.0.0.1 instead of localhost, or remove the ipv6 alias from /etc/hosts.

Got errors like this too.
Problem was my abstract backend referencing two servers.
php-fpm was only listing to socket...

# Upstream to abstract backend connection(s) for php

upstream php {

        server unix:/var/run/php5-fpm.sock;

        #server 127.0.0.1:9000;

} 



server {

    [...]



    location ~ .php$ {

            # NOTE: You should have "cgi.fix_pathinfo = 0;" in php.ini



            # With php5-fpm:

            fastcgi_pass php;

            fastcgi_index index.php;

            fastcgi_intercept_errors on;

            include fastcgi_params;

    }

}

Had the same problem with proxied requests to a Node server listening on port 5000. Requests would result with 200 OK but sometime 502 Bad Gateway randomly. NGINX showed the error:

connect() failed (111: Connection refused) while connecting to upstream, client: ..., server: ...

My solution:

1. Set node HTTP server to listen strictly for ipv4 by including
   localhost as host: server.listen(5000, 'localhost');


2. Removed any ipv6 listen directives (listen [::]:80; or listen
[::]:443 ssl default_server;).


3. Changed location block proxy_pass to use IPs: proxy_pass http://127.0.0.1:5000 (not proxy_pass http://localhost:5000).

Hope this helps someone.