FAQ

What is a Scaler?

A scaler is an individual instance hosting your app. You can attribute one or more Scalers to your apps. Scalers come in many sizes based on each language requirements from Pico to XL.

Each scaler is given a fixed set of resources.

When enabling auto-scalability, you have to set a minimum and a maximum of active scalers in your apps settings. This way you can precisely control your monthly fee.

What languages and frameworks are supported by Clever Cloud?

Currently Clever Cloud supports:

• Java (Play Framework 1 & 2, Maven, War files… )
• Node.js
• PHP (see frameworks and CMS)
• Python (Django)
• Ruby
• Go
• Haskell
• Scala
• Rust
• Docker

How many applications can I create with Clever Cloud?

As many as you want. We’ve not set a limited number of apps by developer.

How to setup domain names I own?

You can bind custom domain names to your applications. Please have a look at Custom Domain Names.

How can I disable one of my existing applications?

Log in with your account to console.clever-cloud.com, and select the appropriate organization and app in the left column. Then click on the application name and select Overview. Click on the Stop button to stop your app.

What type of content is allowed on Clever Cloud?

Please refer to our Terms and Conditions, article 6, Obligations and responsibilities of the client.

How do I add or remove members in my organizations?

Log in with your account to console.clever-cloud.com, and select the appropriate organization in the left panel. Then click on Members in the mid pane. You’ll see a list of the organization’s members. If your are an admin, you can revoke or grant permissions.

How do I report an application that is in violation of your Terms and Conditions?

To report an application that is in violation of Clever Cloud’s Terms and Conditions, please contact us at abuse@clever-cloud.com.

We will investigate and contact the application’s owner over the violation if needed.

Does Clever Cloud support TLS/SSL (HTTPS)?

Absolutely! For testing purposes, cleverapps.io domains support TLS out of the box. For custom SSL certificates, you can either order one from us or use an existing one. Have a look at installing SSL certificates, and feel free to contact us at contact@clever-cloud.com if you have questions.

I’d like to have two applications available on the same domain name

Please refer to prefix routing to learn how to have two applications share a domain name.

How do I define cron jobs for my application?

See Cron Configuration File for more information.

How to know if a user comes from a secure connection?

All connections are handled by load-balancers ahead of your applications and forwarded in plain http, you cannot rely on the server port to know the scheme used by the user.

Instead, you can use the X-Forwarded-Proto HTTP header to get the information, it is set to either ‘http’ or ‘https’.

PHP: $_SERVER auth variables are always empty, how do I make this work?

It’s explained here.

How to get the user’s IP address?

All connections are handled by load-balancers ahead of your applications and forwarded in plain http.

So if you get the REMOTE_ADDR or Client-IP header, you will only get the IP of the front load balancer that forwarded the user request.

Instead of these headers you need to use the X-Forwarded-For HTTP header, which is set by our load balancer to the client’s address. Please remember that it is a list, containing the address of each proxy the request has been through, if the said proxy has modified the X-Forwarded-For header: Read the Wikipedia page for more informations

When my application runs on multiple instances, how can I differentiate them?

If your application needs to differentiate all the running nodes internally, you can use the INSTANCE_NUMBER environment variable.

For example, if 3 instances are running for your application, this environment variable will contain 0 on the first, 1 on the second and 2 on the third.

I need a private ssh key to fetch my private dependencies. How do I do that?

If your company manages its own artifacts in a private repository (like, you can only access them via git+ssh or sftp), and you need a private key to connect to the server, you can commit them in your application’s Clever Cloud repository and then add a clevercloud/ssh.json file.

The ssh.json file is documented here.

I get a java.lang.UnsupportedClassVersionError : Unsupported major.minor version error. How can I fix it?

If you get this error on a Java (or any JVM language) application, it means that your application was compiled with a newer Java version than the one used to run it.

As an example, if a Spring Boot application was compiled with Java 17 and run with Java 11, the following error will occur :

java.lang.UnsupportedClassVersionError: org/springframework/boot/loader/JarLauncher has been compiled by a more recent version of the Java Runtime (class file version 61.0), this version of the Java Runtime only recognizes class file versions up to 55.0

By default, Java 11 is used, but it can be changed. Please head over here for more information.

For reference, the table below lists the class file version for each major Java version (official doc) :

I want SSH access to my server

Clever Cloud does not give you access to a server or a VPS, it makes your application run. Each instance is started and configured automatically, and can be stopped at any moment.

If however, you still need SSH access for debugging purposes, please have a look at SSH access, but keep in mind that changes made on an instance are not persistent across deployments.

I want to user Clever Cloud on my own premises, is that possible?

Yes, since 2016 Clever Cloud is packaged for private datacenter. This offer called “Clever Cloud On Premises” is avaialble upon request: you can send a mail to sales@clever-cloud.com or visit https://www.clever-cloud.com/on-premises for more infos.

Where are my applications and add-ons located?

Applications and add-ons are located in either Paris, France or Montreal, Canada. You can choose where you want it to be when you create an application and a Clever Cloud add-on.

Clever Cloud is based in Nantes, France.

I want to run Kubernetes on top of Clever CLoud, is that possible?

It’s currently not possible to use Kubernetes on our platform. It is however on our Roadmap.

How to setup a firewall on Clever Cloud?

Specific firewall rules can be enabled on demand to the support or in case of attack.

Can I scp something in a VM

You cannot scp something to the VM, you can however easily scp something from the VM to the outside.

I need to convert something to PDF with wkhtmltopdf

wkhtmltopdf is available and fully functional but we deeply recommend to use use chromium headless instead.

What is the timezone used by my application/add-on?

All instances on Clever Cloud run on the UTC timezone. We recommend to handle all your dates in UTC internally, and only handle timezones when reading or displaying dates.

I received an email saying “Addon [my add-on] disk is nearly full”. What do I do?

A full disk can cause your database to crash or become unresponsive. We advise you to check how many free space there is. You might want to do one of the following:

Remove data from your database

Only you know your data!

You can take a snapshot of your database and export the obsolete data to a cold storage. Then you can remove records from your database, reindex your tables and try to perform a VACUUM operation if the database software allows it.

Migrate your add-on to a bigger plan

… Or to the same plan!

You can buy more disk space by migrating your add-on to a higher plan. If a VACUUM operation needs more disk that there is remaining, migrating to the same plan will clean up the file on disk and regain space.

Where are my backups stored?

Clever Cloud store all your backups on Cellar. Cellar has a replication system to protect the data stored inside. It creates three copies of your backups, each stored in a different datacenters in the PAR region.
This way, even if one datacenter has an accident, your backup are still safe in two different datacenters.