.htaccess

# Use the front controller as index file. It serves as fallback solution when
# every other rewrite/redirect fails (e.g. in an aliased environment without
# mod_rewrite). Additionally, this reduces the matching process for the
# startpage (path "/") because otherwise Apache will apply the rewritting rules
# to each configured DirectoryIndex file (e.g. index.php, index.html, index.pl).
DirectoryIndex app.php

<IfModule mod_rewrite.c>
    RewriteEngine On

    # Redirect to URI without front controller to prevent duplicate content
    # (with and without `/app.php`). Only do this redirect on the initial
    # rewrite by Apache and not on subsequent cycles. Otherwise we would get an
    # endless redirect loop (request -> rewrite to front controller ->
    # redirect -> request -> ...).
    # So in case you get a "too many redirects" error or you always get redirected
    # to the startpage because your Apache does not expose the REDIRECT_STATUS
    # environment variable, you have 2 choices:
    # - disable this feature by commenting the following 2 lines or
    # - use Apache >= 2.3.9 and replace all L flags by END flags and remove the
    #   following RewriteCond (best solution)
    RewriteCond %{ENV:REDIRECT_STATUS} ^$
    RewriteRule ^app\.php(/(.*)|$) %{CONTEXT_PREFIX}/$2 [R=301,L]

    # If the requested filename exists, simply serve it.
    # We only want to let Apache serve files and not directories.
    RewriteCond %{REQUEST_FILENAME} -f
    RewriteRule .? - [L]

    # The following rewrites all other queries to the front controller. The
    # condition ensures that if you are using Apache aliases to do mass virtual
    # hosting, the base path will be prepended to allow proper resolution of the
    # app.php file; it will work in non-aliased environments as well, providing
    # a safe, one-size fits all solution.
    RewriteCond %{REQUEST_URI}::$1 ^(/.+)(.+)::\2$
    RewriteRule ^(.*) - [E=BASE:%1]
    RewriteRule .? %{ENV:BASE}app.php [L]
</IfModule>

<IfModule !mod_rewrite.c>
    <IfModule mod_alias.c>
        # When mod_rewrite is not available, we instruct a temporary redirect of
        # the startpage to the front controller explicitly so that the website
        # and the generated links can still be used.
        RedirectMatch 302 ^/$ /app.php/
        # RedirectTemp cannot be used instead
    </IfModule>
</IfModule>