How To Install Discourse on a CentOS 6.4 x64 VPS

About Discourse

Discourse is a new, open-source discussion platform. Designed as a complete ‘reboot’ of discussion forums, it has a different flow from conventional forums and a built in trust system.

Step 1: OS Configuration

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There are a handful of prerequisites for running Discourse; this tutorial will assume a fresh Centos 6 VPS.

Add Swap Space

If you’re running a VPS with less than 2 GB of RAM, you’ll need to enable swap on your VPS. If you do not do so, some build steps are likely to fail.

This tutorial has instructions on enabling swap for CentOS 6. For smaller VPS, add at least 1 GB of swap space.

Create a local, non-root user

Most steps will be run as a non-root user with sudo access. This tutorial will run you through creating a user account and granting it sudo power.

Create a non-root user that will run Discourse

You’ll also need a user account which will run Discourse. It’s best for this to be a different account from your own; discourse would be a good choice.

Add the EPEL repository

EPEL stands for Extra Packages for Enterprise Linux, and it has some packages we’ll need to install that are not part of the base CentOS repositories.

Log in as your local user and run:

sudo su -c 'rpm -Uvh http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm'

Install required packages

These are pre-requisites for Discourse or its pre-requisites.

sudo yum install gcc-c++ patch readline readline-devel zlib zlib-devel libyaml-devel libffi-devel openssl-devel make bzip2 autoconf automake libtool bison iconv-devel ruby-devel libxml2 libxml2-devel libxslt libxslt-devel git

Install and start Redis

Redis is an open-source key value data store used by Discourse.

sudo yum install redis.x86_64
sudo chkconfig --add redis
sudo chkconfig --level 345 redis on
sudo /etc/init.d/redis start

Step 2: Install ngnix

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Ngnix is a lightweight web server and reverse proxy that will be used to reverse proxy connections to Discourse.

Add repository

ngnix is not in the central CentOS repositories, so you will have to add their repository for yum to be able to install ngnix.

Create a text file /etc/yum.repos.d/nginx.repo:

sudo emacs /etc/yum.repos.d/nginx.repo

Paste in this content:

[nginx]
name=nginx repo
baseurl=http://nginx.org/packages/centos/6/$basearch/
gpgcheck=0
enabled=1

Once that’s installed, you need to refresh the yum package list and then install ngnix.

sudo yum upgrade
sudo yum install nginx.x86_64

Step 3: Install PostgreSQL

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Discourse uses PostgreSQL for its data backend. While the EPEL contains packages for PostgreSQL, it’s fairly outdated. This will install a newer package from PostgreSQL’s repository.

Disable CentOS repository

First we’ll tell yum to not look at packages from the core CentOS repository. To do this, edit the file /etc/yum.repos.d/CentOS-Base.repo.

sudo emacs /etc/yum.repos.d/CentOS-Base.repo

Add the line:

exclude=postgresql*

under the [base] and [updates] sections of this file.

Install the PostgreSQL repository

Now we’ll register PostgreSQL’s repository with yum.

curl -O http://yum.postgresql.org/9.1/redhat/rhel-6-i386/pgdg-centos91-9.1-4.noarch.rpm
sudo rpm -ivh pgdg-centos91-9.1-4.noarch.rpm 

Install the PostgreSQL server

This will install the server and some development packages needed by Discourse, start the server, initialize the database, and set it to start on reboot.

sudo yum install postgresql91-server.x86_64 postgresql91-contrib.x86_64 postgresql91-devel.x86_64

sudo service postgresql-9.1 initdb
sudo service postgresql-9.1 start
sudo chkconfig postgresql-9.1 on

Grant permissions to users

Now tell PostgreSQL about our users and give them permission to access the database.

sudo -u postgres createuser -s root
sudo -u postgres createuser -s discourse

Step 4: Install rvm and Ruby

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Ruby and rvm will be installed in single-user context for the discourse user.

Install rvm

Become the discourse user and install the stable branch of rvm:

sudo su - discourse
\curl -s -S -L https://get.rvm.io | bash -s stable

rvm will add some environment setup to the login scripts for the discourse user; to make sure these are set it’s easiest to log out then back in.

exit
sudo su - discourse

Verify packages rvm requires are installed

This will make sure the environment is set up correctly and rvm is ready to work. Again, as the discourse user, run:

rvm --autolibs=read-fail requirements

This should return that no additional packages are required by rvm.

Install ruby

As the discourse user, install a local ruby environment and bundler:

rvm install 2.0.0
rvm use 2.0.0 --default
gem install bundler

Tweak ruby configuration

By default, the gem builder will not be able to find the support libraries and binaries for the system’s PostgreSQL server. In order for this gem to build, this will tell bundle to pass commandline arguments when it builds the PostgresSQL library.

Still as the discourse user, run:

bundle config build.pg --with-pgsql-lib=/usr/pgsql-9.1/lib --with-pg-config=/usr/pgsql-9.1/bin/pg_config

Step 5: Install and Configure Discourse

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Now the system is ready to build and run Discourse.

Build Discourse

As the discourse user, pull down the Discourse source using git. This will clone the Discourse git tree to a sub-folder discourse:

git clone git://github.com/discourse/discourse.git discourse

Once that has copied the source locally, build Discourse:

cd discourse
bundle install --deployment --without test

Configure Discourse

Copy the example configuration files so Discourse will find them:

cd config
cp database.yml.production-sample database.yml
cp redis.yml.sample redis.yml
cp discourse.pill.sample discourse.pill
cp environments/production.rb.sample environments/production.rb

You’ll need to edit database.yml. Change the host_names line to your server’s hostname.

Create database

Return to the discourse directory, and as the discourse user run:

cd ~/discourse
createdb discourse_prod
RUBY_GC_MALLOC_LIMIT=90000000 RAILS_ENV=production rake db:migrate
RUBY_GC_MALLOC_LIMIT=90000000 RAILS_ENV=production rake assets:precompile

The precompile step can take several minutes without printing any output to the screen, so it may appear like the process has hung.

Fix permissions

By default the webserver will not be able to access the discourse directory. To grant more broad permissions, run this as the discourse user:

cd ~
chmod og+rx /home/discourse

Install and configure bluepill

Bluepill is a process monitoring tool that Discourse uses to monitor itself. Install and configure it to start on boot:

gem install bluepill
echo 'alias bluepill="NOEXEC_DISABLE=1 bluepill --no-privileged -c ~/.bluepill"' >> ~/.bash_profile
rvm wrapper $(rvm current) bootup bluepill
rvm wrapper $(rvm current) bootup bundle

Run Discourse

Discourse is now ready to start up. To start Discourse, run:

RUBY_GC_MALLOC_LIMIT=90000000 RAILS_ROOT=/home/discourse/discourse RAILS_ENV=production NUM_WEBS=2 bluepill --no-privileged -c ~/.bluepill load /home/discourse/discourse/config/discourse.pill

You should also configure Discourse to start at bootup by adding this to the discourse user’s crontab. Open up your crontab for editing:

crontab -e

And paste the following line into the editor that pops up:

@reboot RUBY_GC_MALLOC_LIMIT=90000000 RAILS_ROOT=/home/discourse/discourse RAILS_ENV=production NUM_WEBS=2 /home/discourse/.rvm/bin/bootup_bluepill --no-privileged -c ~/.bluepill load /home/discourse/discourse/config/discourse.pill

Discourse is now running, but ngnix needs to be configured to forward requests to the running Discourse server before it will answer requests sent to your hostname.

Step 7: Configure ngnix

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Now configure ngnix to point to the Discourse instance.

Log back in and execute these commands as the local user, not as discourse.

Base ngnix configuration

There’s a small change you’ll need to make to the configuration. Open the /etc/nginx/nginx.conf file:

sudo emacs /etc/nginx/nginx.conf

Find the http section of the file and add the following line:

server_names_hash_bucket_size 64;

Configure nginx for Discourse

Discourse comes with an example nginx configuration file. Copy the example Discourse ngnix configuration to where ngnix expects it:

sudo cp /home/discourse/discourse/config/nginx.sample.conf /etc/nginx/conf.d/discourse.conf

There are a few changes that need to be made to this file. Open the `/etc/nginx/conf.d/discourse.conf’ file:

sudo emacs /etc/nginx/conf.d/discourse.conf

• Change server_name to your hostname.

• Change the socket paths to reflect where Discourse is installed. They should look like this:

upstream discourse {
  server unix:/home/discourse/discourse/tmp/sockets/thin.0.sock;
  server unix:/home/discourse/discourse/tmp/sockets/thin.1.sock;
  server unix:/home/discourse/discourse/tmp/sockets/thin.2.sock;
  server unix:/home/discourse/discourse/tmp/sockets/thin.3.sock;
}

• Change the base path in the file. Look for a line with a path /var/www/discourse/public and replace this with our correct path, /home/discourse/discourse/public.

Now restart ngnix to pick up the configuration changes:

sudo /etc/init.d/nginx stop
sudo /etc/init.d/nginx start

The stop command may fail if ngnix wasn’t currently running, but the start command should succeed.

Step 8: Use Discourse!

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Discourse is now running and responding to requests at your hostname. The last thing you’ll need to do is set up an admin account to give you permission to administrate the Discourse instance.

Create your Discourse user

Open your Discourse website by navigating to your hostname in your webbrowser. Create a user account for yourself and make note of the email address with which you sign up.

Grant yourself administrative priveleges

Return back to your shell. Become the discourse user and bring up a rails console connected to the Discourse instance:

cd ~/discourse
RAILS_ENV=production bundle exec rails c

This will drop you into a Rails console where you can run commands. These commands will grant you administrative access; replace the email address with the email address you signed up with:

me = User.find_by_username_or_email('myemailaddress@me.com')
me.activate
me.admin = true
me.save

You can also set this user as the default contact, as well:

SiteSetting.site_contact_username = me.username

Type exit to quit the Rails console.

Verify you are now an administrator

Return back to your Discourse instance in your webbrowser. If you’re not logged in as the account you signed up for, log back in. You will now be able to configure your Discourse instance to your liking.

Congratulations! You’ve installed Discourse. Huzzah!

<div class=“author”>Submitted by: <a href=“http://jimreardon.us/”>Jim Reardon</a></div>