load balancing random 503

ihamouda1 nginx-forum at nginx.us
Wed Sep 19 06:15:25 UTC 2012 

Hi there
I have an instance on ec2 acting as a load balancer for 4 apache2 servers.
The instance is ubuntu precise with nginx 1.2.3
The instance has 4 computing units and 3.75 GB memory

Everything is working ok, except I get random 503 for some images.
I have a page that loads about 20 images, they never load all, randomly some
of them don't load and not the same ones every time.

Any help is appreciated.

nginx.conf:

user www-data;
worker_processes 8;
pid /var/run/nginx.pid;

events {
	worker_connections 4096;
	# 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;
	map_hash_bucket_size 128;
	# server_name_in_redirect off;
	### override default ssl settings ###
	ssl_session_timeout 10m;
	proxy_ssl_session_reuse off;	
    	ssl_session_cache shared:SSL:16m;
    	ssl_protocols SSLv3 TLSv1;
    	ssl_ciphers
ALL:!ADH:!kEDH:!aNULL:!MD5:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv3:+EXP;
    	#ssl_ciphers  HIGH:!aNULL:!MD5:!kEDH;
    	#ssl_ciphers ALL:!aNULL:!ADH:!eNULL:!MEDIUM:!LOW:!EXP:RC4 RSA: HIGH;
    	ssl_prefer_server_ciphers on;


	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;

	##
	# 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/*;
	include /etc/nginx/cw.conf;
}

cw.conf:

upstream cwbackend {
  ip_hash;
  server cwweb1.domain.com:80;
  server cwweb2.domain.com:80;
  server cwweb3.domain.com:80;
  server cwweb4.domain.com:80;
  keepalive 16;
}

upstream cwsecure {
  ip_hash;
  server cwweb1.domain.com:443;
  server cwweb2.domain.com:443;
  server cwweb3.domain.com:443;
  server cwweb4.domain.com:443;
  keepalive 16;
}



server {

  listen 80;
  server_name cw1.domain.com;
  client_max_body_size 30M;
  location / {
    proxy_http_version 1.1;
    # needed to forward user's IP address to rails
    proxy_set_header  X-Real-IP  $remote_addr;
    proxy_set_header Connection "";
    # needed for HTTPS
    proxy_set_header  X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header Host $http_host;
    proxy_redirect off;
    proxy_max_temp_file_size 0;
    proxy_next_upstream	error timeout invalid_header http_500;
    proxy_connect_timeout	30;
    proxy_read_timeout 360;
    proxy_pass http://cwbackend;

  } #end location

} #end server



server {

  listen 443;
 
  ssl on;
  ssl_certificate /usr/local/src/certs-2011-2014/sslchain.crt;
  ssl_certificate_key /usr/local/src/certs-2011-2014/domain.com.key;
  
  server_name cw1.domain.com;
  client_max_body_size 30M;
  location / {
    proxy_http_version 1.1;
# needed to forward user's IP address to rails
    proxy_set_header  X-Real-IP  $remote_addr;
 	
    # needed for HTTPS
    proxy_set_header X-FORWARDED-PROTO https;
    proxy_set_header    X-FORWARDED-SSL on;
    #proxy_set_header  X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header Host $http_host;
    proxy_set_header Connection "";
    proxy_redirect off;
    proxy_max_temp_file_size 0;
    proxy_buffering off;
    proxy_connect_timeout	30;
    proxy_read_timeout 360;
    proxy_pass https://cwsecure;
  } #end location


} #end server

backend apache2.conf:

LockFile ${APACHE_LOCK_DIR}/accept.lock

PidFile ${APACHE_PID_FILE}

Timeout 2

KeepAlive On

MaxKeepAliveRequests 100

KeepAliveTimeout 15


<IfModule mpm_prefork_module>
    StartServers          5
    MinSpareServers       5
    MaxSpareServers      10
    MaxClients          256
    MaxRequestsPerChild  100
</IfModule>

<IfModule mpm_worker_module>
    StartServers          2
    MinSpareThreads      25
    MaxSpareThreads      75 
    ThreadLimit          64
    ThreadsPerChild      25
    MaxClients          200
    MaxRequestsPerChild   0
</IfModule>

<IfModule mpm_event_module>
    StartServers          2
    MinSpareThreads      25
    MaxSpareThreads      75 
    ThreadLimit          64
    ThreadsPerChild      25
    MaxClients          150
    MaxRequestsPerChild   0
</IfModule>

User ${APACHE_RUN_USER}
Group ${APACHE_RUN_GROUP}


AccessFileName .htaccess

<Files ~ "^\.ht">
    Order allow,deny
    Deny from all
    Satisfy all
</Files>

DefaultType None


HostnameLookups Off

ErrorLog ${APACHE_LOG_DIR}/error.log

LogLevel warn

Include mods-enabled/*.load
Include mods-enabled/*.conf

Include httpd.conf

Include ports.conf

LogFormat "%v:%p %h %l %u %t \"%r\" %>s %O \"%{Referer}i\"
\"%{User-Agent}i\"" vhost_combined
LogFormat "%h %l %u %t \"%r\" %>s %O \"%{Referer}i\" \"%{User-Agent}i\""
combined
LogFormat "%h %l %u %t \"%r\" %>s %O" common
LogFormat "%{Referer}i -> %U" referer
LogFormat "%{User-agent}i" agent


Include conf.d/

Include sites-enabled/

backend site config file:

NameVirtualHost *:443
<VirtualHost *:443>
	ServerAdmin webmaster at domain.com
	ServerName cwweb1.domain.com
	SSLEngine On
	SSLCertificateFile /usr/local/src/domain.com.crt
	SSLCertificateKeyFile /usr/local/src/domain.com.key
	SSLCertificateChainFile /usr/local/src/intermediate.crt
	DocumentRoot /data/www
	DirectoryIndex default.php index.php
	<Directory />
		Options FollowSymLinks
		AllowOverride None
	</Directory>
	<Directory /data/www>
		Options Indexes FollowSymLinks MultiViews
		AllowOverride None
		Order allow,deny
		allow from all
	</Directory>

	ScriptAlias /cgi-bin/ /usr/lib/cgi-bin/
	<Directory "/usr/lib/cgi-bin">
		AllowOverride None
		Options +ExecCGI -MultiViews +SymLinksIfOwnerMatch
		Order allow,deny
		Allow from all
	</Directory>

	ErrorLog /var/log/apache2/error.log

	# Possible values include: debug, info, notice, warn, error, crit,
	# alert, emerg.
	LogLevel warn

	CustomLog /var/log/apache2/access.log combined
	ServerSignature On

    Alias /doc/ "/usr/share/doc/"
    <Directory "/usr/share/doc/">
        Options Indexes MultiViews FollowSymLinks
        AllowOverride None
        Order deny,allow
        Deny from all
        Allow from 127.0.0.0/255.0.0.0 ::1/128
    </Directory>

</VirtualHost>

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,230847,230847#msg-230847

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