On this page

Haskell

Create a Clever Cloud account

The API of Clever Cloud uses OAuth 1 to perform authentication actions. There are two ways to signup to Clever Cloud: email or GitHub login.

Go to the Clever Cloud Console and select the method you prefer.

Email Authentication

This kind of auth requires a valid and non-temporary disposable e-mail, and a password having at least 6 characters. Do not forget to validate your email by clicking the link you will receive.

GitHub Authentication

The GitHub signup allows you to create an account or link your existing one to GitHub, in one click. This process asks the following permsissions: 

  • Read your Public Key
  • Read User Repositories

The “repository permission” is used to deploy your GitHub apps directly to Clever Cloud, with a simple step.

If you need to give access to Clever Cloud’s API to a specific GitHub organization, you can do it here.

Two Factor Authentication (2FA)

Clever Cloud supports 2FA. You can enable it here: https://console.clever-cloud.com/users/me/authentication

Please, backup your recovery codes, we won’t be able to restore access to your account if you lose access to your regular codes.

You need to add a SSH key to your Clever Cloud’s account to deploy via Git. SSH keys are used to establish a secure connection between your computer and Clever Cloud. A user can have multiple SSH keys.

I need to create my SSH key

  1. In your Terminal, enter the following bash line:

    ssh-keygen -t ed25519 -C "your_email@youremail.com"
    

    This command creates a new ssh key using the provided email, so that the owner of the key can be identified.

  2. When prompted in which file you want to save the key, just press entrer. If it says that the file already exists, enter n for no. Type ls, constat the presence of the file and jump to Add your SSH key on Clever Cloud.

  3. When asked, enter a passphrase:

Generating public/private ed25519 key pair.
Enter file in which to save the key (/your_home_path/.ssh/id_ed25519):
# Now you should enter a passphrase.
Enter passphrase (empty for no passphrase): [Type a passphrase]
Enter same passphrase again: [Type passphrase again]

Which should give you something like this:

Your identification has been saved in /your_home_path/.ssh/id_ed25519.
Your public key has been saved in /your_home_path/.ssh/id_ed25519.pub.
The key fingerprint is:
01:0e:e5:2d:ab:98:d6:17:a1:6d:f0:68:9f:d0:a2:db your_email@youremail.com

I created my account with GitHub

If your account is linked to GitHub, a panel with your GitHub SSH keys will appear in the “SSH Keys” tab. You can add any key already present in your GitHub account by clicking on the import button next to it.

Add your SSH key on Clever Cloud

Public SSH Key

To declare your public SSH Key on Clever Cloud, in the left navigation bar, go in “Profile” and in the “SSH Keys” tab, add the key by entering a name and the public SSH key. The key is the entire content of the **id_[ed25519/rsa].pub** file including the id_ed25519/ssh-rsa part and your email.

Private SSH Key

If you want to clone a repository from a private repository, you can add a Private SSH Key to an application by creating a folder clevercloud at the root of your application and creating the file clevercloud/ssh.json with the following content:

{
    "privateKeyFile": "path/to/file"
}

Of course you need to provide a valid path to a file that contains a valid key and that you will push on the Clever Cloud git remote.

If you have trouble configuring this key you can refer to this extended documentation

Create an application on Clever Cloud

via the web console

  1. Create a new app by clicking on the Add an Application button, in the sidebar.
  2. Select a brand new instance (or a repository from GitHub if your account is linked).
  3. Then select Haskell in the platform list.
  4. Configure your scaling options.
  5. Enter your application’s name and description and click “Next”. You can also select the region you want (North America or Europe).

Refer to https://www.clever-cloud.com/doc/getting-started/ for more details on application creation via the console.

via the Clever Tools CLI

  1. Make sure you have clever-tools installed locally. Report to https://www.clever-cloud.com/doc/reference/clever-tools/getting_started/
  2. In your code folder, do clever create --type <type> <app-name> --region <zone> --org <org> where type is the type of technology you rely on, app-name the name you want for your application, zone deloyment zone (par for Paris and mtl for Montreal), and org the organization ID the application will be created under.

Refer to https://www.clever-cloud.com/doc/reference/clever-tools/create/ for more details on application creation with Clever Tools.

Setting up environment variables on Clever Cloud

With the Clever Cloud console

  1. Go to the Clever Cloud console, and find the app you want to fine tune under it’s organization.
  2. Find the Environment variables menu and select it.
  3. In this menu, you will see a form with VARIABLE_NAME and variable value fields. Fill them with the desired values then select Create.

With the Clever Tools CLI

  1. Make sure you have clever-tools installed locally. Report to https://www.clever-cloud.com/doc/reference/clever-tools/getting_started/
  2. In your code folder, do clever env set <variable-name> <variable-value>

Refer to https://www.clever-cloud.com/doc/reference/reference-environment-variables/ for more details on available environment variables on Clever Cloud. You can of course create custom ones with the interface we just demonstrated, they will be available for your application.

Configure your Haskell application

Mandatory configuration

Be sure that:

  • you have pushed in master branch
  • you listen on port 8080
  • you have one and only one binary target in your .cabal file
  • your project has a stack.yaml file

The steps ran in order are:

  • stack setup
  • stack install --only-dependencies
  • stack install
  • ./<path>/my-exe (or the contents of CC_RUN_COMMAND)

The executable built by stack build (or the command you specify) must start a web server listening on 0.0.0.0:8080.

For instance, a minimal scotty application can look like this:

{-# LANGUAGE OverloadedStrings #-}

import Web.Scotty

main = scotty 8080 $ do get "/" $ do html $ "Hello world"

Dependencies

Make sure to list all your dependencies in your .cabal file. For the example above, you need:

  build-depends:       base
                     , scotty

Cached dependencies

Enabling dependencies caching

You can enable dependencies caching by adding the CC_CACHE_DEPENDENCIES=true environment variable in your application. It is enabled by default only for rust and haskell applications.

Disabling dependencies caching

You can disable dependencies caching completely by removing the CC_CACHE_DEPENDENCIES environment variable from the Clever Cloud console, in the Environment variables menu of your application. Or by setting it to CC_CACHE_DEPENDENCIES=false To fully remove cached dependencies, you have to rebuild your application from scratch. You can select “rebuild and restart” from the Clever Cloud console or launch clever restart --without-cache with the Clever Tools CLI.

Custom run command

If you need to run a custom command (or just pass options to the binary built by stack), you can specify it through the CC_RUN_COMMAND environment variable.

For instance, for a hakyll website, you can put

CC_RUN_COMMAND=~./local/bin/site server --host 0.0.0.0 --port 8080

To access environment variables from your code, just get them from the environment with getEnv :: String -> IO String in System.Environment.

If some environment variables are critical to your application, here is an approach you can use:

{-# LANGUAGE OverloadedStrings #-}
module Main where

import Data.Text.Lazy (pack) import System.Environment (getEnv) import Web.Scotty (get, html, scotty)

envVar = getEnv "MY_VAR"

main = do myVar <- envVar scotty 8080 $ do get "/" $ do html . pack $ "Hello world " ++ myVar

This loads the environment variable in your main function and tests it. This way, the application will refuse to start with an helpful error message if MY_VAR is not defined.

Git Deployment on Clever Cloud

You need git on your computer to deploy via this tool. Here is the official website of Git to get more information: git-scm.com

Setting up your remotes

  1. The “Information” page of your app gives you your git deployment URL. It looks like this: git+ssh://git@push.clever-cloud.com/<your_app_id>.git. Copy it in your clipboard.

  2. Locally, under your code folder, type in git init to set up a new git repository or skip this step if you already have one.

  3. Add the deploy URL with git remote add <name> <your-git-deployment-url>.

  4. Add your files via git add <files path> and commit them via git commit -m <your commit message>.

  5. Now push your application on Clever Cloud with git push <name> master

Refer to https://www.clever-cloud.com/doc/getting-started/quickstart/ for more details on git deployments.

Linking a database or any other add-on to your application

By linking an application to an add-on, the application has the add-on environment variables in its own environment by default.

On add-on creation

Many add-ons do exist on Clever Cloud, please refer to the full list and check add-ons dedicated pages for full instructions.

During add-on creation, you will see Applications screen, with a list of your applications. You can toggle the button to Link and click next. If you finish the process of add-on creation, the application will automatically be linked to it.

Add-on already exists

In the Clever Cloud console, under the Service Dependencies menu of your application, you can use the Link addons dropdown menu to select the name of the add-on you want to link and use the add button to finish the process.

You can also link another application from the same page in the Clever Cloud console, using the Link applications dropdown menu.

More configuration

Need more configuration? To run a script at the end of your deployment? To add your private SSH key to access private dependencies? Go check the Common configuration page.

You may want to have an advanced usage of your application, in which case we recommend you to read the Administrate documentation section.

If you can’t find something or have a specific need like using a non supported version of a particular software, please reach out to the support.