How to Install Custom PHP Extensions on Heroku

Thien Tran Duy

In this tutorial, we’ll learn how to install custom extensions on Heroku. Specifically, we’ll be installing Phalcon.

Sign-up and Set up

In order to use Heroku, you must sign up for a Heroku account. Heroku generally works with a command-line interface. To use that interface, you need to install the Heroku toolbelt package for your operating system. If you are using Linux, open up terminal and type the following command.

wget -qO- | sh

After installing the toolbelt, you’ll have access to the heroku command from your command shell. Authenticate using the email address and password you used when creating your Heroku account:

heroku login

Enter your Heroku credentials.
Could not find an existing public key.
Would you like to generate one? [Yn]
Generating new SSH public key.
Uploading ssh public key /home/duythien/.ssh/

Press enter at the prompt to upload your existing ssh key or create a new one, used for pushing code later on.

Phalcon is a third party extension, and thus not bundled with PHP. Phalcon requires the following components:


mbstring and mcrypt are the main ones – mbstring is used by the templating engine (Volt), as well as some validators, the escaper and the filter, while mcrypt is used in the security component (generating secure hashes etc.)

In order to install the elements above, we will use the PHP buildpack tool. Let’s explain what that means.

According to the official Heroku documentation, buildpacks provide the magic and flexibility that make running your apps on Heroku so easy. When you push your code, the buildpack is the component that handles the setting up of your environment so that your application can run. The buildpack can install dependencies, customize software, manipulate assets, and do anything else required to run your application. Heroku didn’t always have buildpacks, they are a new component that came with the Cedar stack.

You can get more information on these three steps and more through the buildpack documentation.

To get started, we fork this code on github. Click the “Fork” button in the repository. To be able to work on the project, you will need to clone it to your local machine.

Run the following code:

git clone buildpack-php
cd buildpack-php

Create the file in your $HOME/buildpack-php/bin directory with the following content:

# Build Path: /app/.heroku/php/
echo "-----> Building Phalcon..."

### Phalcon
echo "[LOG] Downloading PhalconPHP"
git clone $dep_url -q
if [ ! -d "$phalcon_dir" ]; then
  echo "[ERROR] Failed to find phalconphp directory $phalcon_dir"
cd $phalcon_dir/build

# /app/php/bin/phpize
# ./configure --enable-phalcon --with-php-config=$PHP_ROOT/bin/php-config
# make
# make install
ln -s $BUILD_DIR/.heroku /app/.heroku
export PATH=/app/.heroku/php/bin:$PATH
bash ./install
echo "important extension phalcon into php.ini"
echo "" >> /app/.heroku/php/etc/php/php.ini

This file will install Phalcon, but Heroku must be instructed to execute it. To do that, you will have to edit the bin/compile file and add the following line somewhere in there:

source $BP_DIR/bin/phalcon

In addition, you need to add the text to the file “conf/php/php.ini“:

; Local Variables:
; tab-width: 4
; End:

Now we can push our new buildpack up:

git add -A
git commit -m "edit php.ini and create phalcon file"
git push origin master

Create a new application on Heroku

Create a directory for your app and change to it:

mkdir phalcon-dev
cd phalcon-dev

In addition, you need to give Heroku an indication that this application is a PHP application. To do this, create an empty file called composer.json. On a Unix system, you can create this file like so:

touch composer.json

Then, execute the following to initalize the repo for our app:

git init
git add -A
git commit -m" first commit"

To create a new Heroku application that you can push to, use the CLI’s create command:

heroku create phalcon-dev

Creating phalcon-dev... done, stack is cedar |
Git remote heroku added

This creates the application on Heroku ready and waiting for our code, and also attaches a git remote to our local codebase. You are now ready to deploy the application, but there is no code yet. Follow the next section to add some content to your application.

Your composer.json file should be made to look like this:

  "require": {
    "php": "5.5.12"

It will automatically install extensions such as mcrypt, mbstring, etc on Heroku. If you need mongodb, memcached, etc, modify the file further:

  "require": {
    "php": "5.5.12",
    "ext-memcached": "*",
    "ext-mongo": "*"

Now Heroku will enable the corresponding PHP extensions and put them into the support/build/extensions/no-debug-non-zts-20121212 folder. Next, create a test.php file with the following content:

<?php phpinfo() ; ?>

Finally, let’s deploy the Phalcon installation:

heroku config:set BUILDPACK_URL=
git add -A
git commit -am "installl phalcon"
git push heroku master

The first command means override the Heroku default buildpack by specifying a custom buildpack in the BUILDPACK_URL config var. After a few minutes, the results are as follows:

Build complete.
Don't forget to run 'make test'.

Installing shared extensions:     /app/.heroku/php/lib/php/extensions/no-debug-non-zts-20121212/

Thanks for compiling Phalcon!
Build succeed: Please restart your web server to complete the installation
important extension phalcon into php.ini
-----> Discovering process types
       Procfile declares types -> (none)
       Default types for PHP   -> web

-----> Compressing... done, 124.0MB
-----> Launching... done, v8 deployed to Heroku

   4f1d993..e0936a5  master -> master

This has taken our code, pushed it to Heroku, identified it, and run a build process against it, making it ready for deployment. Now our application is live on the Internet! To verify this, open it now:

heroku open test.php

If everything goes fine, you should see the following screen in your browser:


Configure the web root and deploy the sample site

Now comes the tricky part that is specifying the web root. Specifying the web root needs a little bit more work and background information. The Phalcon website application’s root in the git tree is /app/phalcon-website/public. For Heroku, by default, the web root is the root of the git-tree. That directory is internally mapped to /app. To change this, we need to create a so called Procfile that starts a sh-script each time the Heroku app web-node starts. That script then modifies the server configuration and includes your own config which is setting the web root to /app/phalcon-website/public. Create a Procfile file with the following content (if you’re using Apache):

web: vendor/bin/heroku-php-apache2 phalcon-website/public

Clone the Phalcon website into the repo folder, and when it’s done, the git push command sends all of the commits on your local master to the central repository.

cd && cd phalcon-dev
git clone --depth=1 phalcon-website
git add Procfile phalcon-websiste/
git commit -am " test phalcon website"
git push heroku master

Visit the app’s public URL and voila, you have a running clone on Heroku here.

Phalcon website

In conclusion

Installing Phalcon (or any other PHP extension) on Heroku is obviously neither easy nor simple but if you use buildpacks, it becomes much more approachable.

Leave your feedback in the comments below and, as always, please share this article if you liked it!