Buildpack

Setting Buildpacks

Heroku officially supports buildpacks for Ruby, Node.js, Clojure, Python, Java, Gradle, Grails, Scala, Play, PHP and Go.

Buildpacks are automatically detected by Heroku in the above order, however, it can also be set manually through CLI using:

At the time of app creation

 heroku create <app_name> --buildpack <buildpack_name>

Manually,
```
 heroku buildpacks:set <buildpack_name>
```

Buildpack name can be specified either using shorthand or URL. Like for PHP buildpack,

heroku buildpacks:set heroku/php

heroku buildpacks:set https://elements.heroku.com/buildpacks/heroku/heroku-buildpack-php

Multiple buildpacks

An application can also contain more than one buildpack. It can be achieved using add:

heroku buildpacks:add --index 1 <buildpack_name>

where, --index parameter specifies the execution order of buildpack.

Say,

heroku buildpacks:set heroku/php
heroku buildpacks:add --index 1 heroku/nodejs

will set the buildpack order as:

heroku/nodejs
heroku/php

Remember: A Heroku app has only one public port - 80. Hence either of the one will serve in one port. Say, if procfile is specified with web: node server.js, node application will run in port 80, otherwise PHP. However, the build will run in the order specified. If one needs more than one application, set up multiple projects and make it to communicate with each other.