upstream prematurely closes cnx => 502 Bad Gateway to client

[B.R.]

The HTTP specification states every request shall receive a response.
Your backend closes the connection while nginx is awaiting/reading the
headers.

The problem definitely comes from your backend. You could use tcpdump
between nginx and your backend to record what they say to each other.
​Try to correlate logs from nginx with logs from your backend.​
---
*B. R.*

On Thu, Mar 3, 2016 at 11:57 AM, stefws <nginx-forum at forum.nginx.org> wrote:

> My config btw:
>
> user  imail;
> worker_processes  auto;
> daemon on;
> master_process on;
> error_log  logs/mos_error.tcp  debug_tcp;
> error_log  logs/mos_error.log;
> pid        /opt/imail/nginx/logs/mos_nginx.pid;
> worker_rlimit_nofile 200000;
> worker_rlimit_core  500M;
> working_directory   /opt/imail/nginx;
> events {
>     worker_connections  25000;
>     use epoll;
>     multi_accept off;
> }
> http {
>     log_format testlogs '$remote_addr - $remote_user [$time_local]  '
>      '"$request" $status $body_bytes_sent '
>      '"$http_referer" "$upstream_addr" '
>      '$request_time $upstream_response_time';
>     access_log logs/mos_access.log;
>     sendfile on;
>     keepalive_requests 500000;
>     keepalive_timeout 20s;
>     tcp_nopush on;
>     tcp_nodelay on;
>     client_body_buffer_size 128k;
>     client_body_temp_path /dev/shm/mos_nginx/client_temp 1 2;
>     open_file_cache max=25000 inactive=30s;
>     open_file_cache_valid    60s;
>     open_file_cache_min_uses 2;
>     open_file_cache_errors   on;
>     upstream mosgenericbackend {
>         server mss1:8081;
>         server mss2:8081;
>         server mss3:8081;
>         server mss4:8081;
>         healthcheck_enabled;
>         healthcheck_delay 1000;
>         healthcheck_timeout 1000;
>         healthcheck_failcount 2;
>         healthcheck_send 'GET /mxos/monitor HTTP/1.0';
>         keepalive 300;
>     }
>     server {
>         listen 8081;
>         keepalive_timeout 600s;
>         client_max_body_size 0;
>         location /mxos/ {
>             proxy_http_version 1.1;
>             proxy_set_header Connection "";
>             proxy_pass http://mosgenericbackend;
>             proxy_connect_timeout 2;
>             more_set_headers "Content-Type: application/json";
>         }
>         location /mxos/health_status {
>             healthcheck_status;
>         }
>         proxy_connect_timeout 60;
>         proxy_read_timeout  30;
>         proxy_send_timeout 60;
>     }
> }
>
> My [vendor patched/supplied due to application specific load
> balancing+health check] nginx version:
>
> # /opt/imail/nginx/sbin/nginx -V
> nginx version: nginx/1.7.4
> built by gcc 3.4.6 20060404 (Red Hat 3.4.6-3)
> TLS SNI support disabled
> configure arguments: --with-debug
>
> --add-module=/bld/current/emailmx90_git_blds/emailmx90_contrib_shared/contrib/nginx_1.7.4/source/addons/healthcheck_nginx_upstreams-master
>
> --add-module=/bld/current/emailmx90_git_blds/emailmx90_contrib_shared/contrib/nginx_1.7.4/source/addons/headers-more-nginx-module-0.23
>
> --add-module=/bld/current/emailmx90_git_blds/emailmx90_contrib_shared/contrib/nginx_1.7.4/source/addons/yaoweibin-nginx_tcp_proxy_module-f2156ef
>
> Posted at Nginx Forum:
> https://forum.nginx.org/read.php?2,265031,265032#msg-265032
>
> _______________________________________________
> nginx mailing list
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>
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