Deploying CodeIgniter on EC2 via Dokku

Using the Git post-receive hook to deploy your static site is lightweight and convenient, but doesn't quite work for applications that require backing services like a database or a file upload service.

is a more feature-complete fork of , and allows you to turn any server into a Heroku-like platform where all you need to do is a single git push to deploy an app.

Here is a short guide on deploying a PHP app to an Amazon EC2 instance:

Create the EC2 instance

, select any instance size and SSD you like, and make sure you open TCP ports 80 and 443 (HTTP and HTTPS).

Install dokku-alt

Connect to your instance via SSH and create a TCP tunnel to remote port 2000:

macbook$ ssh -L 2000:localhost:2000 ubuntu@<IP_ADDRESS>

Then run the :

ubuntu@ip-1-2-3-4:~$ sudo bash -c "$(curl -fsSL https://raw.githubusercontent.com/dokku-alt/dokku-alt/master/bootstrap.sh)"

The script will open a web server on port 2000; open , paste your public SSH key, and leave virtualhost naming disabled for now.

Prepare the CodeIgniter app

To deploy a CodeIgniter app to dokku-alt, you'll need to by configuring and a Procfile.

Add a file composer.json with the following contents:

{
  "require": {
    "php": "~5.6.0"
  },
  "require-dev": {
    "heroku/heroku-buildpack-php": "*"
  }
}

Add a file Procfile with the following contents:

web: vendor/bin/heroku-php-apache2

Run composer update, then your project structure should look something like this:

.
├── application/
├── system/
├── vendor/
├── .gitignore
├── .htaccess
├── composer.json
├── composer.lock
├── index.php
├── license.txt
└── Procfile

Deploy the app

Add a Git remote that points to your new dokku-alt instance, then push:

macbook$ git remote add dokku dokku@<IP_ADDRESS>:myapp
macbook$ git push dokku

The output should then tell you where the application is deployed, for example:

...
remote: =====> Application deployed:
remote:        http://<IP_ADDRESS>:49153
...

Since we haven't enabled virtualhost naming, the app is served on an app-specific port. Only ports 22, 80, and 443 are open, so you need to open an SSH tunnel to access the app port:

macbook$ ssh -L 8080:localhost:49153 ubuntu@<IP_ADDRESS>

Then open .

Attach the database

If your application requires a database, you can use dokku-alt to create a database container for either (a MySQL-compatible database), , or .

For example, add a MariaDB container:

ubuntu@ip-1-2-3-4:~$ dokku mariadb:create myapp

Then link it to your app:

ubuntu@ip-1-2-3-4:~$ dokku mariadb:link myapp myapp

A new DATABASE_URL environment variable should now be configured for the app. For example:

ubuntu@ip-172-31-39-239:~$ dokku config myapp
=== myapp config vars ===
DATABASE_URL: mysql2://myapp:PW5HDJs0KhmoUOZH@mariadb:3306/myapp

Configure environment variables

Now that your app is deployed with a database, you need to configure it to connect using the supplied DATABASE_URL variable. CodeIgniter does not have a built-in way to specify the database connect with a URL, so we need to parse it.

In application/config/database.php:

<?php
...
$database_url = getenv("DATABASE_URL");
$url=parse_url(getenv("DATABASE_URL"));
$server = $url["host"];
$username = isset($url["user"]) ? $url["user"] : '';
$password = isset($url["pass"]) ? $url["pass"] : '';
$database = substr($url["path"], 1);


$db['default']['hostname'] = $server === 'localhost' ? '127.0.0.1' : $server;
$db['default']['username'] = $username;
$db['default']['password'] = $password;
$db['default']['database'] = $database;
$db['default']['dbdriver'] = 'mysqli';
...

Note that the database driver is set to 'mysqli' instead of the default 'mysql'; the MariaDB container is not compatible with the deprecated 'mysql' driver.

.

It would also be ideal for our app to throw an exception if the required environment variables are not set. We can use CodeIgniter hooks to check the environment before calling a controller:

Enable hooks in application/config/config.php:

<?php
...
$config['enable_hooks'] = TRUE;
...

Specify the hook in application/config/hooks.php:

<?php
...
$hook['pre_controller'] = array(
  'class'    => '',
  'function' => 'check_environment',
  'filename' => 'Environment.php',
  'filepath' => 'hooks'
);
...

Finally, implement the hook in application/hooks/Environment.php:

<?php

/**
 * Ensure that environment variables are set
 */
function check_environment() {
    if (!(getenv("DATABASE_URL")))
        throw new Exception('Must set a DATABASE_URL environment variable');
}

Add these changes and git push them to dokku, and your application should connect to the database.

.