bob_cobb bob_cobb - 1 month ago 29
Node.js Question

Nginx 502 Bad Gateway when uploading files

I get the following error when I try to upload files to my node.js based web app:

2014/05/20 04:30:20 [error] 31070#0: *5 upstream prematurely closed connection while reading response header from upstream, client: ... [clipped]


I'm using a front-end proxy here:

upstream app_mywebsite {
server 127.0.0.1:3000;
}

server {
listen 0.0.0.0:80;
server_name {{ MY IP}} mywebsite;
access_log /var/log/nginx/mywebsite.log;

# pass the request to the node.js server with the correct headers and much more can be added, see nginx config options
location / {
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Host $http_host;
proxy_set_header X-NginX-Proxy true;

proxy_pass http://app_mywebsite;
proxy_redirect off;
# web socket support
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
}
}


This is my nginx.conf file:

user www-data;
worker_processes 4;
pid /run/nginx.pid;

events {
worker_connections 2048;
multi_accept on;
}

http {

##
# Basic Settings
##

sendfile on;
tcp_nopush on;
tcp_nodelay on;
keepalive_timeout 20;
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;
default_type text/html;
charset UTF-8;

##
# 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_min_length 256;
gzip_comp_level 5;
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;

##
# nginx-naxsi config
##
# Uncomment it if you installed nginx-naxsi
##

#include /etc/nginx/naxsi_core.rules;

##
# nginx-passenger config
##
# Uncomment it if you installed nginx-passenger
##

#passenger_root /usr;
#passenger_ruby /usr/bin/ruby;

##
# Virtual Host Configs
##

include /etc/nginx/conf.d/*.conf;
include /etc/nginx/sites-enabled/*;
}


Any idea on how to better debug this? The things I've found haven't really worked (e.g. removing the tailing slash from my proxy_pass

Answer

So in the end I ended up changing in my keepalive from 20 to 64 and it seems to handle large files fine now. The bummer about it is that I re-wrote from scratch the image upload library I was using node-imager, but at least I learned something from it.

server {
  location / {
    keepalive 64
  }
}
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