Nginx proxy-pass - ipv6 deaktivieren

Habe ich nginx conf wie folgt:

server {
listen       127.0.0.1:8080;
server_name  127.0.0.1;

client_max_body_size 20m;

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

# redirect server error pages to the static page /50x.html                                                                                                                                              
#                                                                                                                                                                                                       
error_page   500 /500.json;
error_page   501 /501.json;
error_page   502 /502.json;
error_page   503 /503.json;
error_page   504 /504.json;
error_page   404 /404.json;

location = /500.json {
    root   /opt/lj/nginx;
}
location = /501.json {
    root   /opt/lj/nginx;
}
location = /502.json {
    root   /opt/lj/nginx;
}
location = /503.json {
    root   /opt/lj/nginx;
}
location = /504.json {
    root   /opt/lj/nginx;
}
location = /404.json {
    root  /opt/lj/nginx;
}
}

In der conf.d/services-Verzeichnis habe ich eine Datei mit:

location /api/auth {proxy_pass     http://127.0.0.1:8081;}

Habe ich einen upstream-Prozess hören auf 8081 für Anfragen. Fast genau 2 unserer 3 mal, die Anfrage wird umgeleitet entsprechend, aber in jedem Dritten mal, bekomme ich diesen Fehler:

2014/10/09 03:03:52 [alert] 4572#0: *16 socket() failed (97: Address family not supported by protocol) while connecting to upstream, client: 127.0.0.1, server: 127.0.0.1, request: "GET /api/auth/1.0/companies/1/clients HTTP/1.1", upstream: "http://[::1]:8081/api/auth/1.0/companies/1/clients", host: "localhost:8080"

Ich weiß nicht, wie man nginx nur bei uns auf der IPv4-Adresse, die der upstream versteht.

Access logs: (Bitte beachten Sie 1 von 3 versuche Ergebnisse in 500 während der rest pass)

127.0.0.1 - portalAdmin [09/Oct/2014:02:56:37 -0400] "GET /api/auth/1.0/companies/1/clients HTTP/1.1" 500 107 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/38.0.2125.101 Safari/537.36" "98.207.234.244"
127.0.0.1 - portalAdmin [09/Oct/2014:02:57:38 -0400] "GET /api/auth/1.0/companies/1/clients HTTP/1.1" 200 2 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/38.0.2125.101 Safari/537.36" "98.207.234.244"
127.0.0.1 - portalAdmin [09/Oct/2014:02:57:39 -0400] "GET /api/auth/1.0/companies/1/clients HTTP/1.1" 200 2 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/38.0.2125.101 Safari/537.36" "98.207.234.244"
127.0.0.1 - portalAdmin [09/Oct/2014:02:57:41 -0400] "GET /api/auth/1.0/companies/1/clients HTTP/1.1" 500 107 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/38.0.2125.101 Safari/537.36" "98.207.234.244"
127.0.0.1 - portalAdmin [09/Oct/2014:03:03:44 -0400] "GET /api/auth/1.0/companies/1/clients HTTP/1.1" 200 2 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/38.0.2125.101 Safari/537.36" "98.207.234.244"
127.0.0.1 - portalAdmin [09/Oct/2014:03:03:45 -0400] "GET /api/auth/1.0/companies/1/clients HTTP/1.1" 200 2 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/38.0.2125.101 Safari/537.36" "98.207.234.244"
127.0.0.1 - portalAdmin [09/Oct/2014:03:03:46 -0400] "GET /api/auth/1.0/companies/1/clients HTTP/1.1" 500 107 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/38.0.2125.101 Safari/537.36" "98.207.234.244"
127.0.0.1 - portalAdmin [09/Oct/2014:03:03:50 -0400] "GET /api/auth/1.0/companies/1/clients HTTP/1.1" 200 2 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/38.0.2125.101 Safari/537.36" "98.207.234.244"
127.0.0.1 - portalAdmin [09/Oct/2014:03:03:51 -0400] "GET /api/auth/1.0/companies/1/clients HTTP/1.1" 200 2 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/38.0.2125.101 Safari/537.36" "98.207.234.244"
127.0.0.1 - portalAdmin [09/Oct/2014:03:03:52 -0400] "GET /api/auth/1.0/companies/1/clients HTTP/1.1" 500 107 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/38.0.2125.101 Safari/537.36" "98.207.234.244"

Jede Hilfe wäre sehr geschätzt werden! Danke.