title: Docker TYPO3 Directory / is not writable
body: <p>I created my own docker environment for TYPO3. It also starts. The problem is I can't install TYPO3 because I don't grant write rights to the folders.<br>
  <code>ERROR:' Path /var/www/html exists, but no file underneath it can be created.'</code>
  <a href="https://i.stack.imgur.com/ljGTI.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ljGTI.png" alt="enter image description here"></a></p>
  
  <p>Here is my dockerfile  &amp; docker-compose.yml for apache and PHP Setup: </p>
  
  <p>Any Solutions how I can fix this issue?</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
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  <pre class="snippet-code-html lang-html prettyprint-override"><code>FROM php:7.0-apache
  
  # PHP Extensions
  RUN docker-php-ext-install pdo_mysql
  
  
  # Composer
  RUN php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"
  RUN php composer-setup.php
  RUN php -r "unlink('composer-setup.php');"
  RUN mv composer.phar /usr/local/bin/composer
  
  
  ADD vhost-default.conf /etc/apache2/sites-enabled/000-default.conf
  
  # Open Ports
  EXPOSE 80
  EXPOSE 443</code></pre>
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  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>  app:
      build:
        context: ./Docker/apache
        dockerfile: Dockerfile
      container_name: apache
      ports:
          - "8090:80"
          - "443:443"
      volumes:
          - .:/var/www/html
      environment:
          - API_TOKEN=xxxx</code></pre>
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