Apache versus nginx configuration: "Server lost session", "wasClean": false

[Tirthankar Chakravarty]

Hello, 

I am running identical Shiny code on two servers with apache2 as the reverse proxy on one and nginx as the reverse proxy on the other. Apache2 works perfectly, but with nginx, I constantly get the "Disconnected from server" dialog, and the console tells me: 

Mon Jun 20 2016 18:45:23 GMT+0530 (India Standard Time): Connection closed. Info: {"type":"close","code":1006,"reason":"Server lost session","wasClean":false}

Here is my nginx configuration: 

user www-data;

worker_processes 4;

pid /run/nginx.pid;

events {

worker_connections 768;

        multi_accept on;

}

http {

  map $http_upgrade $connection_upgrade {

      default upgrade;

      ''      close;

    }

  server {

    listen 80;

    

    location / {

      proxy_pass http://localhost:3838;

      proxy_redirect http://localhost:3838/ $scheme://$host/;

      proxy_http_version 1.1;

      proxy_set_header Upgrade $http_upgrade;

      proxy_set_header Connection "upgrade";

      proxy_send_timeout 7d;      

      proxy_read_timeout 24d;

      proxy_connect_timeout 24d;

    }

  }

    ##

# 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;

# server_name_in_redirect off;

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/*;

}

Here is my apache2 configuration -- this is untouched from default, see the configuration file below for the changes that I have made to get apache2 to reverse proxy Shiny: 

# This is the main Apache server configuration file.  It contains the

# configuration directives that give the server its instructions.

# See http://httpd.apache.org/docs/2.4/ for detailed information about

# the directives and /usr/share/doc/apache2/README.Debian about Debian specific

# hints.

#

#

# Summary of how the Apache 2 configuration works in Debian:

# The Apache 2 web server configuration in Debian is quite different to

# upstream's suggested way to configure the web server. This is because Debian's

# default Apache2 installation attempts to make adding and removing modules,

# virtual hosts, and extra configuration directives as flexible as possible, in

# order to make automating the changes and administering the server as easy as

# possible.

# It is split into several files forming the configuration hierarchy outlined

# below, all located in the /etc/apache2/ directory:

#

# /etc/apache2/

# |-- apache2.conf

# | `--  ports.conf

# |-- mods-enabled

# | |-- *.load

# | `-- *.conf

# |-- conf-enabled

# | `-- *.conf

# `-- sites-enabled

# `-- *.conf

#

#

# * apache2.conf is the main configuration file (this file). It puts the pieces

#   together by including all remaining configuration files when starting up the

#   web server.

#

# * ports.conf is always included from the main configuration file. It is

#   supposed to determine listening ports for incoming connections which can be

#   customized anytime.

#

# * Configuration files in the mods-enabled/, conf-enabled/ and sites-enabled/

#   directories contain particular configuration snippets which manage modules,

#   global configuration fragments, or virtual host configurations,

#   respectively.

#

#   They are activated by symlinking available configuration files from their

#   respective *-available/ counterparts. These should be managed by using our

#   helpers a2enmod/a2dismod, a2ensite/a2dissite and a2enconf/a2disconf. See

#   their respective man pages for detailed information.

#

# * The binary is called apache2. Due to the use of environment variables, in

#   the default configuration, apache2 needs to be started/stopped with

#   /etc/init.d/apache2 or apache2ctl. Calling /usr/bin/apache2 directly will not

#   work with the default configuration.

# Global configuration

#

#

# ServerRoot: The top of the directory tree under which the server's

# configuration, error, and log files are kept.

#

# NOTE!  If you intend to place this on an NFS (or otherwise network)

# mounted filesystem then please read the Mutex documentation (available

# at <URL:http://httpd.apache.org/docs/2.4/mod/core.html#mutex>);

# you will save yourself a lot of trouble.

#

# Do NOT add a slash at the end of the directory path.

#

#ServerRoot "/etc/apache2"

#

# The accept serialization lock file MUST BE STORED ON A LOCAL DISK.

#

Mutex file:${APACHE_LOCK_DIR} default

#

# PidFile: The file in which the server should record its process

# identification number when it starts.

# This needs to be set in /etc/apache2/envvars

#

PidFile ${APACHE_PID_FILE}

#

# Timeout: The number of seconds before receives and sends time out.

#

Timeout 300

#

# KeepAlive: Whether or not to allow persistent connections (more than

# one request per connection). Set to "Off" to deactivate.

#

KeepAlive On

#

# MaxKeepAliveRequests: The maximum number of requests to allow

# during a persistent connection. Set to 0 to allow an unlimited amount.

# We recommend you leave this number high, for maximum performance.

#

MaxKeepAliveRequests 100

#

# KeepAliveTimeout: Number of seconds to wait for the next request from the

# same client on the same connection.

#

KeepAliveTimeout 5

# These need to be set in /etc/apache2/envvars

User ${APACHE_RUN_USER}

Group ${APACHE_RUN_GROUP}

#

# HostnameLookups: Log the names of clients or just their IP addresses

# e.g., www.apache.org (on) or 204.62.129.132 (off).

# The default is off because it'd be overall better for the net if people

# had to knowingly turn this feature on, since enabling it means that

# each client request will result in AT LEAST one lookup request to the

# nameserver.

#

HostnameLookups Off

# ErrorLog: The location of the error log file.

# If you do not specify an ErrorLog directive within a <VirtualHost>

# container, error messages relating to that virtual host will be

# logged here.  If you *do* define an error logfile for a <VirtualHost>

# container, that host's errors will be logged there and not here.

#

ErrorLog ${APACHE_LOG_DIR}/error.log

#

# LogLevel: Control the severity of messages logged to the error_log.

# Available values: trace8, ..., trace1, debug, info, notice, warn,

# error, crit, alert, emerg.

# It is also possible to configure the log level for particular modules, e.g.

# "LogLevel info ssl:warn"

#

LogLevel warn

# Include module configuration:

IncludeOptional mods-enabled/*.load

IncludeOptional mods-enabled/*.conf

# Include list of ports to listen on

Include ports.conf

# Sets the default security model of the Apache2 HTTPD server. It does

# not allow access to the root filesystem outside of /usr/share and /var/www.

# The former is used by web applications packaged in Debian,

# the latter may be used for local directories served by the web server. If

# your system is serving content from a sub-directory in /srv you must allow

# access here, or in any related virtual host.

<Directory />

Options FollowSymLinks

AllowOverride None

Require all denied

</Directory>

<Directory /usr/share>

AllowOverride None

Require all granted

</Directory>

<Directory /var/www/>

Options Indexes FollowSymLinks

AllowOverride None

Require all granted

</Directory>

#<Directory /srv/>

# Options Indexes FollowSymLinks

# AllowOverride None

# Require all granted

#</Directory>

# AccessFileName: The name of the file to look for in each directory

# for additional configuration directives.  See also the AllowOverride

# directive.

#

AccessFileName .htaccess

#

# The following lines prevent .htaccess and .htpasswd files from being

# viewed by Web clients.

#

<FilesMatch "^\.ht">

Require all denied

</FilesMatch>

#

# The following directives define some format nicknames for use with

# a CustomLog directive.

#

# These deviate from the Common Log Format definitions in that they use %O

# (the actual bytes sent including headers) instead of %b (the size of the

# requested file), because the latter makes it impossible to detect partial

# requests.

#

# Note that the use of %{X-Forwarded-For}i instead of %h is not recommended.

# Use mod_remoteip instead.

#

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 of directories ignores editors' and dpkg's backup files,

# see README.Debian for details.

# Include generic snippets of statements

IncludeOptional conf-enabled/*.conf

# Include the virtual host configurations:

IncludeOptional sites-enabled/*.conf

# vim: syntax=apache ts=4 sw=4 sts=4 sr noet

And here is "sites-enabled/000-default.conf" that gets called by "apache2.conf": 

<VirtualHost *:80>

  <Proxy *>

    Allow from localhost

  </Proxy>

        <Location />

                AuthType Basic

                AuthName "Restrcted Access - Authenticate"

                AuthUserFile /etc/httpd/htpasswd.users

                Require valid-user

        </Location>

  ProxyPassMatch ^/(.+)/websocket ws://localhost:3838/$1/websocket

  ProxyPass / http://localhost:3838/

  ProxyPassReverse / http://localhost:3838/

  ProxyRequests Off

</VirtualHost>

Is there any reason that nginx disconnects where apache2 works perfectly? 

Thanks,

T

[Erik Westlund]

Try adjusting your keepalive timeout.  Right now it's set commented out in your config file and that shoudl default to 75 seconds.

http://nginx.org/en/docs/http/ngx_http_core_module.html#keepalive_timeout

Nginx will close out connections that are unused and this might be your issue.  Try extending 75s to 300s (5 minutes) and see if your problem persists.

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[Tirthankar Chakravarty]

Hi Erik, 

Thanks for your response -- that parameter was in fact included, but I was experimenting with commenting it out. In either case I get the same issue. I have also tried varying that parameter to a large value (650s). 

One observation that I have is that the connection loss appears to happen on $(document).ready() so to speak. 

T

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Tirthankar Chakravarty
+91 99670 59990
t.chakra...@cantab.net
tirthankar....@gmail.com

[Tirthankar Chakravarty]

I was able to resolve this, based on this answer: http://stackoverflow.com/a/11875443/1414455

Had to include the line: `include  /etc/nginx/mime.types;` under `location / {`.  

So, for completeness, here is what the "nginx.conf" file looks like: 

user www-data;

worker_processes 4;

pid /run/nginx.pid;

events {

worker_connections 768;

        multi_accept on;

}

http {

  map $http_upgrade $connection_upgrade {

      default upgrade;

      ''      close;

    }

  server {

    listen 80;

    

    location / {

      include  /etc/nginx/mime.types;

      proxy_pass http://localhost:3838;

      proxy_redirect http://localhost:3838 $scheme://$host/websocket;

      proxy_http_version 1.1;

      proxy_set_header Upgrade $http_upgrade;

      proxy_set_header Connection "upgrade";

      proxy_send_timeout 7d;      

      proxy_read_timeout 24d;

      proxy_connect_timeout 24d;

    }

  }

    ##

# Basic Settings

##

sendfile on;

tcp_nopush on;

tcp_nodelay on;

    keepalive_timeout 650s;

# server_names_hash_bucket_size 64;

server_name_in_redirect 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";

##

# Virtual Host Configs

##

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

}

HTH,

T

[valenti...@gmail.com]

понедельник, 20 июня 2016 г., 19:32:25 UTC+6 пользователь Tirthankar Chakravarty написал:

Hello, 

I am running identical Shiny code on two servers with apache2 as the reverse proxy on one and nginx as the reverse proxy on the other. Apache2 works perfectly, but with nginx, I constantly get the "Disconnected from server" dialog, and the console tells me: 

Hey

Can you check if your apache server are working at all with 'service httpd status' or 'service apache2 status' ?

I can't found a 'Listen' directive in your Apache config and I can't sure that your Apache instance is running on 3838 port as nginx expected.
Can you connect to the apache on that port?

Try to look here for working example.

[Tirthankar Chakravarty]

Valentin, 

Thanks for your reply, but I am not sure that you are addressing the question that I have. For me it is an either-or scenario, where I am proxying Shiny server using either Apache or nginx as a proxy server. When I proxy using Apache (configuration as below) things work flawlessly, but when I proxy using nginx (configuration as below) things are not so smooth. 

Shiny server obviously has its own configuration, but I am using the default configuration file, which you can find here: https://github.com/rstudio/shiny-server/blob/master/config/default.config. 

I was looking to understand how I can make the nginx configuration functionally similar to the Apache configuration, and why I was getting the session connection lost issues. 

Hope that helps clarify, 

T

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