Quirks & constraints

Limits, restrictions, permissions — aren't there always some? Heads up so it doesn't cost you hours of researching in the wrong direction.

Service scope

Apps are lightweight containers optimized for speedy web delivery of PHP applications. Apps are specialized to do just that. Apps are single-purpose by design. Apps are also managed.

No 1-click installers

When creating an App we ask for the desired software you are about to use. This can be Laravel, Craft CMS, WordPress or alike. That will not install the software for you. Please don't expect one-click-installers here. This is self service PHP hosting for professional developers. We believe in a clear separation of concerns where you will take care of the code you'll write and use and where we will manage the infrastructure. We also expect you to have a local development environment, see the local dev article.

No root shell

Professional Apps only have remote SSH execution. Universal Apps come with an SSH environment, but that is not a root shell, it's "jailed". So you can use it for deployment and for common tasks around development. Therefore, it's NOT possible to install software like: FFmpeg, Node, NPM, Gulp, webpack, ruby, Rails or mailserver.

We do this for security and performance reasons. Embrace the idea of decoupled services, don't let your users wait, while your application is crunching a video or some images. Consider using an alternative or a third party service.

The Pro Stack has the Worker Component to have CPU intensive long running tasks run in the background, but again only for software you can install via Composer.

Need to call via php interpreter

To launch a PHP script you need to specify the PHP interpreter explicitly: for example, php artisan or php craft.

No image optimization tools

Tools like jpegoptim, optipng, pngquant, SVGO, gifsicle and alike can help to reduce file size of your images. Using such tools are considered a best practice today. Unfortunately they consume a lot of CPU time and memory. fortrabbit Apps are build for fast short running light processes, not heavy lifting. Consider using a third party service for this.

No video compressing

ffmpeg and ffprobe alike are also not available to avoid overuse of resources.


wkhtmltopdf is a popular library to convert HTML to PDF. It's NOT installed and you can not install it on your own for the reasons named above. Check out the following alternatives:

  • dompdf is a PHP only PDF by CSS renderer
  • Use PDF as a service like cloudconvert or others
  • Rethink if you really need PDF? An invoice in HTML is sometimes ok too
  • Consider PDF creation on the client side with JS in the browser, with jsPDF or similar


Apps are designed for fast web delivery — to answer page requests swiftly. Unlike a VPS, which is a multi-purpose box, Apps are single-purpose for web delivery. Installing CPU intensive software would hurt the performance.


We believe in a clear division of security. In a nutshell: We - fortrabbit - take care of the Operating System level and the PHP runtime, you - the developer - are responsible for the software you write and use. Installing additional software would blur that strict division.

Service location

Data center locations are available in Ireland (AWS EU-1) and Virginia / USA (AWS US-EAST-1). A data center can be chosen for each App individually, but can't be changed later on. The service is available in Euro (€) or US Dollars ($): This can be chosen with each Billing Contact. The fortrabbit headquarters is based in Berlin, time zone is: CET.


Sendmail — the Mail Transfer Agent — is not available on fortrabbit.

In PHP Sendmail is usually used with the mail() function. Back in the good ol' days, this would simply call the shell command sendmail from the shell to send a mail directly from the web server to the receiving mail server.

In recent days, this is a really bad practice: your web server can send mails, but not receive any - it is not a mail server. So it is not distinguishable from any home PC part of a bot net. Long story short: it is very likely that your mail will not be received.

Direct SMTP

There is no mailing built-in here. Instead of sendmail you can use a mail script that uses SMTP (Simple Mail Transfer Protocol) via your e-mail provider - usually the one that provides your domain - directly.

There are countless possibilities how to use SMTP. Most frameworks and CMS give them to you out of the box. If you use a custom script, have a look at Swift Mailer. There are special solutions for WordPress, Laravel & Symfony.

A better solution might be to use a "transactional mail service", those are built to do the bulk mailing — see extending fortrabbit. You can either connect to them via "SMTP relay" or by "API". Those services help you to save your App's resources, are probably more reliable and have some nice extra features like analytics and debugging.



Our runtime implements PHP via FastCGI + FPM. To utilize PATH_INFO you need to do a small hack-around in your .htaccess file:

RewriteCond %{REQUEST_URI} \.php/ [NC]
RewriteRule ^(.+)\.php/(.+)$    /$1.php [NC,L,QSA,E=PATH_INFO:/$2]

Basic authentication

If you want to use HTTP basic authentication, you need to forward the Authorization header via an .htaccess directive and parse the contents manually.

Authorization header

If you need the Authorization header, for OAuth for example, you have to forward the header explicitly via an ENV variable:

RewriteCond %{HTTP:Authorization} .
RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]


The PHP extension HTTP from PECL is enabled by default. The classes HttpRequest, HttpResponse and HttpMessage are a very handy replacement for curl and the like. The downside is that it breaks CakePHP in some cases. You can disable the extension in your Settings -> Extensions tab of your App.

Available locales


Branch name matters

Only the branches main, master and the {{app-name}} will be deployed to the webspace. More here.

Release package limit

To keep deployment fast for everyone the size of the release package is limited to 200 MB. Read on.

MySQL with persistent connections during upgrade

When scaling (up or down) your MySQL, your App's database will be migrated to a new node. Therefore the CNAME target of your App's MySQL hostname will be changed. The hostname's time to live (TTL) is 60 seconds, which reflects the maximum expected downtime during upgrade.

With persistent connections this can take longer (possibly up to half an hour). Therefore we recommend to disable persistent connections during upgrades and downgrades.

Outgoing IP address

In some cases you need to know your App's IP address, like for payment processing or in environments that are behind a firewall.

For Professional Apps on production level plans, the outgoing IP address is fixed. All outgoing traffic from these Apps is routed through a NAT gateway. The traffic from Apps will appear to others as coming from these addresses:


This is also true for Workers but not during deployment.

For Universal Apps and for Pro Apps on development plans the IP address is not guaranteed. Although it will most probably not change during the lifetime of an App. You can see this for yourself with a PHP script. Querying an HTTP service like that from an App is the easiest way to determine the current IP address.

echo file_get_contents("https://ifconfig.co/");

Depending on your needs, it is possible to use an HTTP proxy provider like QuoteGuard to get a static IP address.

Finally, there is also the official list of AWS IP ranges and the same list in JSON format.

Do bear in mind, the place where you shell into with ssh or push with git is called the deploy service. The IP address of the deploy service may change.


We do not intend to change the IP address of the deploy services, but we do not guarantee it.

What this isn't

Embrace the idea of decoupled services! We don't offer some classical hosting providers standards such as:

  • Plesk, cPanel, ISPconfig, any classical hosting control panel
  • e-mail hosting, e-mail address configuration
  • any WebMail, so no RoundCube or SquirrelMail
  • Domain ordering, top level domain registration services
  • pre-installed phpMyAdmin, phpBB, Wikis …
  • one-click installers

Our advice to you, the professional developer: consider abandoning your all-in-one old school hosting.

All articles

Craft CMS


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The Dashboard


Tips & tricks




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