Table of Contents
Introduction
There are two methods to scaling an application, service, server, etc. The first, vertical scaling, calls for more resources to a machine. The second, horizontal scaling, calls for a separation of functionality to create a more piecemeal assembly of parts.
For example, does a machine spit out memory errors in the syslog? It may make sense to just add more RAM or a swapfile. However, let's say the database server is growing to a large amount of entries and the web server alone is starting to increase in traffic – a better idea may be to set up a more controllable environment (not to mention more cost effective). To do so, a separation of the web server and database server into separate machines is the key. That is horizontal scaling.
Requirements
- Two droplets each running Debian 7. Each VPS should have completed Initial Server Setup tutorial.
- A basic understanding of Linux commands and what they do. See An Introduction to Linux Basics for a good starting point.
- You will need to have installed Laravel successfully on one of the droplets. This tutorial will work for NGINX + Laravel 4 (skip the *Wrap Up* step): Laravel + Nginx
Do not install a database on the same virtual server as your Laravel install
For the sake of simplicity, we will refer to the first droplet with the Laravel and Nginx install as the *Laravel droplet* with an IP of 192.0.2.5. The second droplet with the PostgreSQL install will be called the *database droplet* with an IP of 192.0.2.1.
Prepping the Database
Horizontal scaling is a rather simple concept that can be come rather complex when you start thinking about more advanced topics such as database replication and load balancing. However we'll only be covering a basic separation of services: the web server frontend and the database backend. Luckily PostgreSQL and Laravel make this a rather simple process.
First we will need to install PostgreSQL on our *database droplet*:
sudo apt-get install postgresql
Next, we must create a database and user within the server that will have the proper permissions to interact with the database. To do so, we must log into the PostgreSQL server:
sudo -u postgres psql
First, let's create the database user:
~~~
CREATE USER databaseuser WITH PASSWORD 'password';
GRANT CREATE ON SCHEMA public TO databaseuser;
GRANT USAGE ON SCHEMA public TO databaseuser;
~~~
Then create the database with the user as the owner and then quit the server:
~~~
CREATE DATABASE mydatabase WITH OWNER databaseuser;
\q
~~~
Next, the database droplet will need to know that it's okay for the Laravel droplet to connect to it. PostgreSQL has a client authentication file that makes this super easy.
sudo nano /etc/postgresql/9.1/main/pg_hba.conf
Add a line that includes the connection, database name, database user, address to be accepted, and the method of connection:
~~~
host mydatabase databaseuser 192.0.2.5/32 md5
~~~
Save and exit, then open up postgresql.conf and find the line that says "listen_addresses = 'localhost'".
sudo nano /etc/postgresql/9.1/main/postgresql.conf
~~~
listen_addresses = '192.0.2.1'
~~~
You may also change this value to one that will accept any address:
~~~
listen_addresses = '*'
~~~
Save, exit, and restart the PostgreSQL server:
sudo service postgresql restart
Configuring Laravel
—
The first thing that needs to be done is to give PHP some knowledge of how to work with the PostgreSQL server. Do so by installing the php5-pgsql extension.
sudo apt-get install php5-pgsql
sudo service php5-fpm restart
Next we need to tell Laravel where our database server is located and how to access it. If you followed the NGINX + Laravel tutorial, then Laravel should be installed at /var/www/laravel.
sudo nano /var/www/laravel/app/config/database.php
First let's have Laravel use it's PostgreSQL driver:
~~~
'default' => 'pgsql',
~~~
Next, let's setup information about the PostgreSQL server.
~~~
'pgsql' => array(
'driver' => 'pgsql',
'host' => '192.0.2.1',
'database' => 'mydatabase',
'username' => 'databaseuser',
'password' => 'password',
'charset' => 'utf8',
'prefix' => '',
'schema' => 'public',
),
~~~
Save and exit.
Testing the Connection
—
To test this connection, let's run a migration in from the command line that will help build our database tables out.
Note: Migrations isn't an extra package to be installed. It comes with laravel and it's a set of commands to interact with our database.
First enter the application directory where artisan is located.
cd /var/www/laravel
Great! Now it's time to install migrations and see if our database connection is working.
php artisan migrate:install
If this command runs successfully without errors you should see a new table in your database called migrations.
Wrapping it Up
—
As you can see, splitting servers is rather simple. By combining horizontal scaling with vertical scaling, a sysadmin can achieve separation of services and increased performance. Even better these methods require 0 extra software.
