How To Use PostgreSQL with Your Ruby on Rails Application on Ubuntu 14.04

This tutorial requires that have a working Ruby on Rails development environment. If you do not already have that, you may follow the tutorial in this link: How To Install Ruby on Rails with rbenv on Ubuntu 14.04.

You will also need to have access to a superuser, or sudo, account, so you can install the PostgreSQL database software.

Once you’re ready, let’s install PostgreSQL.

If you don’t already have PostgreSQL installed, let’s do that now.

First, update apt-get:

sudo apt-get update

Then install PostgreSQL and its development libraries:

sudo apt-get install postgresql postgresql-contrib libpq-dev

PostgreSQL is now installed but you should create a new database user, that your Rails application will use.

Create a PostgreSQL superuser user with this command (substitute the highlighted word with your own username):

sudo -u postgres createuser -s pguser

If you want to set a password for the database user, enter the PostgreSQL console with this command:

sudo -u postgres psql

The PostgreSQL console is indicated by the postgres=# prompt. At the PostgreSQL prompt, enter this command to set the password for the database user that you created:

\password pguser

Enter your desired password at the prompt, and confirm it.

Now you may exit the PostgreSQL console by entering this command:

\q

Let’s create a Rails application now.

Create a new Rails application in your home directory. Use the -d postgresql option to set PostgreSQL as the database, and be sure to substitute the highlighted word with your application name:

cd ~
rails new appname -d postgresql

Then move into the application’s directory:

cd appname

The next step is to configure the application’s database connection.

Configure Database Connection

The PostgreSQL user that you created will be used to create your application’s test and development databases. We need to configure the proper database settings for your application.

Open your application’s database configuration file in your favorite text editor. We’ll use vi:

vi config/database.yml

Under the default section, find the line that says “pool: 5” and add the following lines under it. It should look something like this (replace the highlighted parts with your PostgreSQL user and password):

  host: localhost
  username: pguser
  password: pguser_password

Save and exit.

Create Application Databases

Create your application’s development and test databases by using this rake command:

rake db:create

This will create two databases in your PostgreSQL server. For example, if your application’s name is “appname”, it will create databases called “appname_development” and “appname_test”.

If you get an error at this point, revisit the previous subsection (Configure Database Connection) to be sure that the host, username, and password in database.yml are correct. After ensuring that the database information is correct, try creating the application databases again.

The easiest way to test that your application is able to use the PostgreSQL database is to try to run it.

For example, to run the development environment (the default), use this command:

rails server

This will start your Rails application on your localhost on port 3000.

If your Rails application is on a remote server, and you want to access it through a web browser, an easy way is to bind it to the public IP address of your server. First, look up the public IP address of your server, then use it with the rails server command like this (substitute it for the highlighted part):

rails server --binding=server_public_IP

Now you should be able to access your Rails application in a web browser via the server’s public IP address on port 3000:

http://server_public_IP:3000

If you see the “Welcome aboard” Ruby on Rails page, your application is properly configured, and connected to the PostgreSQL database.

You’re now ready to start development on your Ruby on Rails application, with PostgreSQL as the database, on Ubuntu 14.04!

Good luck!