localhost causes "Index of /" page

I am trying to dockerize my app. I have managed to start up 4 local containers: apache, codedigniter, php, and mariaDB. I have copied my source code into ./app. Now when I type localhost in the browser I get the following rather than my CI application running. What am I doing wrong?

index of /

• .dockerignore
  
  
• .editorconfig
  
  
• .git/
  
  
• .gitignore
  
  
• .idea/
  
  
• .profile
  
  
• .vagrant/
  
  
• APPATHcache/
  
  
• Configure.php
  
  
• Configure_old.php
  
  
• Dockerfile
  
  
• OptionTransfer.js
  
  
• Terms of Service.pdf
  
  
• Vagrantfile
  
  
• Welcome.php
  
  
• apache-vhost/
  
  
• app.yaml
  
  
• app/
  
  
• assets/
  
  
• backup/
  
  
• blank.php
  
  
• classes/
  
  
• composer.json
  
  
• composer.lock
  
  
• composer.phar
  
  
• config.php
  
  
• contributing.md
  
  
• css/
  
  
• docker-compose (copy).yml
  
  
• docker-compose.yml
  
  
• docker-compose.yml_bak
  
  
• examples/
  
  
• file.txt
  
  
• file2.txt
  
  
• images/
  
  
• index.php
  
  
• js/
  
  
• khtest.php
  
  
• license.txt
  
  
• list.php
  
  
• mariadb-data/
  
  
• myfile.json
  
  
• output.txt
  
  
• phpinfo.php
  
  
• phpstorm.php
  
  
• readme.rst
  
  
• resetPassword.php
  
  
• resetPassword.phpold
  
  
• sampleData.json
  
  
• session_cookies/
  
  
• testy5/
  
  
• uploads/
  
  
• user_guide/
  
  
• vendor/
  
  
• vhosts/
  
  
• webhost.conf
  
  
• xdebug.1.so
  
  
• xdebug.2.so
  
  
• xdebug.3.so
  
  
• xdebug.4.so
  

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