title: Heroku PHP document root issues
body: <p>I have a PHP app on heroku, which was deployed without issues as the following repository structure:</p>
  
  <pre><code>myapp
  ├── connect.php
  ├── elec.php
  ├── index.php
  └── key.php
  </code></pre>
  
  <p>I cloned the app on a different machine, and reorganised the app as follows:</p>
  
  <pre><code>myapp
  ├── auth-server
  │   ├── composer.json
  │   ├── connect.php
  │   ├── election.php
  │   ├── index.php
  │   └── key.php
  ├── poll-server
  └── Procfile
  </code></pre>
  
  <p>with the Procfile containing the following:</p>
  
  <blockquote>
    <p>web: vendor/bin/heroku-php-apache2 auth-server/</p>
  </blockquote>
  
  <p>However, the deployement fails with the following message:</p>
  
  <pre><code>Enumerating objects: 35, done.
  Counting objects: 100% (35/35), done.
  Delta compression using up to 4 threads
  Compressing objects: 100% (29/29), done.
  Writing objects: 100% (34/34), 58.78 KiB | 2.35 MiB/s, done.
  Total 34 (delta 7), reused 0 (delta 0)
  remote: Compressing source files... done.
  remote: Building source:
  remote:
  remote: -----&gt; App not compatible with buildpack: https://buildpack-registry.s3.amazonaws.com/buildpacks/heroku/php.tgz
  remote:
  remote:  !     ERROR: Application not supported by this buildpack!
  remote:  !
  remote:  !     The 'heroku/php' buildpack is set on this application, but was
  remote:  !     unable to detect a PHP codebase.
  remote:  !
  remote:  !     A PHP app on Heroku requires a 'composer.json' at the root of
  remote:  !     the directory structure, or an 'index.php' for legacy behavior.
  remote:  !
  remote:  !     If you are trying to deploy a PHP application, ensure that one
  remote:  !     of these files is present at the top level directory.
  remote:  !
  remote:  !     If you are trying to deploy an application written in another
  remote:  !     language, you need to change the list of buildpacks set on your
  remote:  !     Heroku app using the 'heroku buildpacks' command.
  remote:  !
  remote:  !     For more information, refer to the following documentation:
  remote:  !     https://devcenter.heroku.com/articles/buildpacks
  remote:  !     https://devcenter.heroku.com/articles/php-support#activation
  remote:
  remote:
  remote:        More info: https://devcenter.heroku.com/articles/buildpacks#detection-failure
  remote:
  remote:  !     Push failed
  remote: Verifying deploy...
  remote:
  remote: !       Push rejected to myapp.
  remote:
  To https://git.heroku.com/myapp.git
   ! [remote rejected] master -&gt; master (pre-receive hook declined)
  error: failed to push some refs to 'https://git.heroku.com/myapp.git'
  </code></pre>
  
  <p>Since I have both, index.php and composer.json, at the document root specified by the Procfile, the error message does not seem to provide accurate information on what's missing.</p>
  
  <p>Further, I checked out the commit that worked on the previous machine (which is also the current deployed version) only to find it now failing with the same message as above.</p>