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Joe Miller

Ops/Engineering. Continuous DevOping at Webscale

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Graylog2 is an open-source self-hosted centralized log management tool. Think of it as a do-it-yourself version of, or perhaps a simpler alternative to Splunk. Logs are stored in a MongoDB database.

I won’t go into too much detail, so if you want more info check out [](

Graylog2 consists of two components: graylog2-server , a Java process which receives logs and writes them to a MongoDB database. graylog2-web-interface , a Ruby on Rails app that seems happiest with modern versions of Ruby and Rails. CentOS 5, however, ships with an old version of Ruby (1.8.x) which did not play nicely with all of the gems that graylog2 wanted.

If the server is going to be dedicated to only running graylog2, we could probably overwrite the installed Ruby with a newer version. However, the server we wanted to install it on was already running a complex Rails app under mod_passenger which we did not want to risk breaking.

I decided to see if RVM - Ruby Version Manager - would allow me to setup an isolated Ruby environment just for graylog2 and not disturb the other Ruby apps on the machine. I also wanted to setup an isolated instance of Passenger-standalone for graylog2 then configure apache to listen on port 80 and forwarding requests with mod_proxy.

Everything worked even better than I expected. In the Ruby world, with so much rapid change, it can be challenging to put together a compatible set of gems for multiple apps running on the same machine. RVM worked so well I will consider using it to provide isolated ruby environments for other apps in the future. I love RVM!

Here is how I put it all together:


  • Install graylog2-server in /opt/graylog2-server
  • Install graylog2-web-interface in /opt/graylog2-web-interface
  • graylog2-web-interface runs as unprivileged ‘graylog’ user
  • RVM installed to provide a Ruby 1.9.2 and Rails 3.x environment for graylog2-web-interface
  • Passenger-standalone installed in the Ruby 1.9.2 environment, running graylog2-web-interface on
  • Apache listens on tcp/80 and forwards to Passenger-standalone with mod_proxy

MongoDB install

  1. install mongodb from EPELyum repo
# yum install mongodb mongodb-server
# mkdir /var/lib/mongodb
# chown -R mongodb:mongodb /var/lib/mongodb/
  1. enable mongod to start on boot
# chkconfig mongod on
  1. start mongod (logfile: /var/log/mongodb/mongodb.log)
# service mongod start
  1. run mongo, create an admin user in the admin collection and and a graylog user in a new graylog2 collection
# mongo
     use admin
     db.addUser('admin', 'admin-mongo-passwd')
     db.auth('admin', 'admin-mongo-passwd')
     use graylog2
     db.addUser('grayloguser', 'grayloguser-mongo-passwd')

graylog2-server install

based on:

  1. download latest graylog2-server tarball:
  2. Install into /opt/graylog2-server:
# cd /opt
# tar xfvz ~/graylog2-server-0.9.5p1.tar.gz
# ln -s /opt/graylog2-server-0.9.5p1 /opt/graylog2-server
  1. configure /etc/graylog2.conf
# cp graylog2.conf.example /etc/graylog2.conf

edit /etc/graylog2.conf, set monogdb_user, mongodb_password
  1. create /etc/init.d/graylog2-server
# graylog2-server: graylog2 message collector
# chkconfig: - 98 02
# description: This daemon listens for syslog and GELF messages and stores them in mongodb

NOHUP=`which nohup`


start() {
    echo "Starting graylog2-server ..."
    $NOHUP $JAVA_CMD -jar $GRAYLOG2_SERVER_HOME/graylog2-server.jar > /var/log/graylog2.log 2>&1 &

stop() {
        PID=`cat /tmp/`
    echo "Stopping graylog2-server ($PID) ..."
        kill $PID

restart() {
    echo "Restarting graylog2-server ..."

case "$CMD" in
        echo "Usage $0 {start|stop|restart}"
  1. create /etc/logrotate.d/graylog2-server
/var/log/graylog2.log {
       rotate 90
  1. register graylog2-server init script
# chmod +x /etc/init.d/graylog2-server
# chkconfig --add graylog2-server
# chkconfig graylog2-server on
  1. start graylog2-server
# service graylog2-server start
# ps aux | grep graylog2
    root 23197 2.3 0.1 1196204 18428 pts/0 Sl 12:37 0:00 java -jar ../graylog2-server.jar

graylog2-web-interface install

based on:

  1. Install RVM and prepare a new Ruby 1.9.2 environment
# bash
  1. create ‘graylog’ user
# adduser -m graylog
  1. download latest graylog2-web-interface tarball:
# mkdir /opt
# cd /opt
# tar xfvz ~/graylog2-web-interface-0.9.5.tar.gz
# ln -s /opt/graylog2-web-interface-0.9.5 /opt/graylog2-web-interface
# chown -R graylog /opt/graylog2-web-interface-0.9.5
  1. Install gems necessary to run graylog2 using Bundler in the ruby 1.9.2 environment
# rvm use 1.9.2
# cd /opt/graylog2-web-interface
# gem install bundler
# bundle install
  1. Configure graylog2-web-interface
    • Edit the various config files in /opt/graylog2-web-interface to suit your environment:
    • email.yml
    • general.yml
    • mongoid.yml (make sure to use the user/pass you setup earlier)
  2. Start graylog2-web-interface, create first user
# rvm use 1.9.2
# cd /opt/graylog2-web-interface
# RAILS_ENV=production script/rails server

Connect to If everything is working, graylog2 will ask you to create the first user. Shutdown graylog2 (ctrl-C) after you create the first user.

  1. Install and configure passenger-standalone
# yum -y install curl-devel
# rvm use 1.9.2
# gem install passenger
# gem install file-tail

# cd /opt/graylog2-web-interface
# mkdir tmp log
# chmod -R 777 tmp log
# passenger start

Passenger should download, compile, and build everything it needs. If passenger tries to serve requests, ctrl-C to quit.

  1. Create /etc/init.d/graylog2-web-interface
# graylog2-web-interface: graylog2 web interface
# chkconfig: - 98 02
# description: Starts graylog2-web-interface using passenger-standalone. \
# Uses RVM to use switch to a specific ruby version.

# config

# --

CMD_START="cd $APP_DIR; rvm use $RVM_RUBY; passenger start -d \
                    -a $ADDR \
                    -p $PORT \
                    -e $ENVIRONMENT \
                    --user $USER"
CMD_STOP="cd $APP_DIR; rvm use $RVM_RUBY; passenger stop -p $PORT"

CMD_STATUS="cd $APP_DIR; rvm use $RVM_RUBY; passenger status -p $PORT"

. /lib/lsb/init-functions
case "$1" in
    echo "Starting graylog2-web-interface"
    su - $USER -c "$CMD_START"
    echo "Stopping graylog2-web-interface"
    su - $USER -c "$CMD_STOP"
   su - $USER -c "$CMD_STATUS"
    echo "Usage: $0 start|stop|status" >&2
    exit 3
  1. Create /etc/logrotate.d/graylog2-web-interface
       rotate 90
  1. Register graylog2-web-interface service
# chmod +x /etc/init.d/graylog2-web-interface
# chkconfig --add graylog2-web-interface
# chkconfig graylog2-web-interface on
  1. Start graylog2-web-interface
# service graylog2-web-interface start
  1. Configure apache to forward requests to passenger

    1. Create /etc/httpd/conf.d/graylog2.conf
NameVirtualHost *:80

	ProxyPreserveHost On
	ProxyPass /
	ProxyPassReverse /

        CustomLog /var/log/httpd/ common
  1. Restart apache
# service httpd configtest
# service httpd restart

Startup scripts for running multiple Passenger-standalone instances:

If you need a method for setting up multiple Passenger-standalone Rails apps, checkout these scripts. They’re very well done:

Alternatives to Apache

rippleAdder posted example configs on the graylog2 mailing list for running graylog2-web-interface with other webservers than Apache, namely unicorn and nginx. These are likely going to be faster than apache, although I haven’t benchmarked any webservers with graylog2 yet. You can find his sample configs here