I'm using tomcat as a backend (using websocket), and is hostead on AWS behind a balancer. After a some time (acording to timeouts) I'm starting to get the error that the upstream sent no valid HTTP/1.0, but what is strange, is that I'm only using HTTP/1.1, this is my configuration:

------------
# This file was overwritten during deployment by .ebextensions/customs.config
user nginx;
error_log /var/log/nginx/error.log warn;
pid /var/run/nginx.pid;
worker_processes auto;
worker_rlimit_nofile 133650;

events {
worker_connections 10240;
}

http {
include /etc/nginx/mime.types;
default_type application/octet-stream;
client_max_body_size 0; # disable any limits to avoid HTTP 413

log_format main '$remote_addr - $remote_user [$time_local] "$request" '
'$status $body_bytes_sent "$http_referer" '
'"$http_user_agent" "$http_x_forwarded_for" JSESSIONID="$cookie_JSESSIONID"';

log_format main_ext '$remote_addr - $remote_user [$time_local] "$request" '
'$status $body_bytes_sent "$http_referer" '
'"$http_user_agent" "$http_x_forwarded_for" '
'"$host" sn="$server_name" '
'rt=$request_time '
'ua="$upstream_addr" us="$upstream_status" '
'ut="$upstream_response_time" ul="$upstream_response_length" '
'cs=$upstream_cache_status JSESSIONID="$cookie_JSESSIONID"';

include conf.d/*.conf;

map $http_upgrade $connection_upgrade {
default "upgrade";
}

server {
listen 80 default_server;
access_log /var/log/nginx/access.log main_ext;

client_header_timeout 60;
client_body_timeout 60;
keepalive_timeout 60;
gzip on;
gzip_comp_level 4;
gzip_types text/plain text/css application/json application/javascript application/x-javascript text/xml application/xml application/xml+rss text/javascript;

# Include the Elastic Beanstalk generated locations (We are commenting this in order to add some CORS configuration)
# include conf.d/elasticbeanstalk/*.conf;

location / {
proxy_pass http://127.0.0.1:8080;
proxy_http_version 1.1;

proxy_buffers 16 16k;
proxy_buffer_size 16k;

proxy_set_header Connection $connection_upgrade;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}

location ~* \.(jpe?g|png|gif|ico|css|woff)$ {
proxy_pass http://127.0.0.1:8080;
proxy_http_version 1.1;
add_header 'Access-Control-Allow-Origin' '*';
add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
}

location /nginx_status {
stub_status on;
allow 127.0.0.1;
deny all;
}
}
}
-----------

There is nothing in conf.d/*.conf


I do have a lot of Writing, but I'm guessing that's because of the websocket.

# curl localhost/nginx_status;lsof -n -u nginx | awk '{print $5}' | sort | uniq -c | sort -nr
Active connections: 1029
server accepts handled requests
62963 62963 342949
Reading: 0 Writing: 1016 Waiting: 13
2053 IPv4
338 REG
81 unix
28 0000
24 CHR
20 DIR
2 FIFO
1 TYPE




If I set the timeout on the balancer and proxy_read_timeout on 4.000 seconds (the max available), I'm able to live without errors for an hour until I need to restart the tomcat server. We haven't make any configuration change for the last year but I'm guessing I'm hitting some limit, but I can't find what is it