Deploy Go applications

Overview

Clever Cloud allows you to deploy any Go application. This page will explain you how to set up your application to run it on our service.

We currently support single module applications only. That means that your sources files just need to be at the project’s root, and you can’t have multiple modules running.

You do not need to change a lot in your application, the requirements will help you configure your applications with some mandatory files to add, and properties to setup.

Create an application on Clever Cloud

via the web console

Refer to our 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 or follow our CLI getting started guide.
2. In your code folder, do clever create --type <type> <app-name> --region <zone> --org <org> where :
   1. type is the type of technology you rely on
   2. app-name the name you want for your application,
   3. zone deployment zone (par for Paris and mtl for Montreal)
   4. org the organization ID the application will be created under.

Refer to clever 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.
4. Fill them with the desired values then select Add.
5. Don’t forget to “Update Changes” at the end of the menu.

With the Clever Tools CLI

1. Make sure you have clever-tools installed locally. Refer to our CLI getting started.
2. In your code folder, do clever env set <variable-name> <variable-value>

Refer to environment variables reference 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 Go application

Mandatory configuration

Be sure that:

• Your application listens to the wild network 0.0.0.0, not only localhost or 127.0.0.1
• Your application listens on port 8080
• You put your main code in a file named main.go (if you do not do that, Go will generate a library and not an executable)

Apart from listening on port 8080, there is nothing to change on your application.

Go production build on Clever Cloud

• We automatically build and run your application, see Build the application.
• By default, we consider that your repository contains a single application. We put your application in ${GOPATH}/src/{app_id} and then run go get {app_id}. Refer to clevercloud/go.json settings if you want to override this behaviour.
• By default, we deploy your application as a Go project named “<app_id>”. You can find the app_id of your application under the environment variable APP_ID. Please refer to environment injection to know how to query it in your application.
• The executable is run with the application’s root as its current path. So if your application has a static folder at its root, it will be accessible via ./static in your application.

Build the application

To build your application, you can use one of the three methods available:

• go modules
• go build
• go get (default)

Go modules

If your project is compatible with go modules, be sure that the go.mod file is in your git tree. Note that it must be at the root of your application (see the APP_FOLDER environment variable if it isn’t

For now, you have to add the environment variable CC_GO_BUILD_TOOL=gomod to build using the go modules. In a future release, we will automatically build with go modules if the go.mod file is present at the root of your git tree.

Your project’s entrypoint should be in the same folder as the go.mod file and be named main.go. If it isn’t, you have to specify it using the following environment variable:

CC_GO_PKG=./path/to/entrypoint.go

Go build

If your project does not support go modules, it may include your vendored dependencies. In this case, go build must be used.

To use go build, you have to set the CC_GO_BUILD_TOOL=gobuild environment variable. We will then deploy your project in a classic GOPATH hierarchy using go build.

The CC_GO_PKG environment variable can be used to define the main file of your application. Defaults to main.go.

Go get

• If your application has submodules and imports them with their full path or your main project is an external package hosted, for instance on GitHub (like github.com/me/myproject), you can define the environment variable CC_GO_PKG=github.com/me/myproject. We will now run go get ${CC_GO_PKG} instead of go get <app_id>.

Also, go get requires that you put your main code in a file named main.go. If you do not do that, go will generate a library and not an executable. So if you get a Nothing listening on port 8080, please check that your main file is named main.go.

You can also force the use of go get by setting the environment variable CC_GO_BUILD_TOOL=goget. This is currently the default.

Note: if you get a Nothing listening on port 8080 error, please check that your main file is named main.go.

Customize build using environment variables

clevercloud/go.json

This configuration file is optional.

If you want to configure precisely your dependencies (e.g. have private libraries, or specific versions of some libraries), here is the way:

1. Make your repository have a GOPATH structure:

   ./
   src/
       myapp/
       foo/
           module1/
           module2/
       module3/
   

   Here you have the modules myapp, foo/module1, foo/module2 and module3.

2. Create a clevercloud/go.json file at the top of your repository:

   ./
   clevercloud/
               go.json
   src/
       myapp/
       ...
   

3. In the go.json file, put the following:

   {
       "deploy": {
           "appIsGoPath": true,
           "main": "myapp"
       }
   }
   

   If appIsGoPath is present and equals true, then we consider that your repo root is the GOPATH.

   The main field then becomes mandatory and must be the name of the module you want to run.

   E.g. if you want to run module1, main must be foo/module1.

4. (Optional) Add a “execDir” field to the “deploy” object:

   {
       "deploy": {
           "appIsGoPath": true,
           "main": "myapp",
           "execDir": "src/myapp"
       }
   }
   

The execDir value must be relative to the root of your repo.

In the example above, we will run the application in the src/myapp directory.

Environment injection

Clever Cloud injects environment variables from your application settings as mentioned in setting up environment variables and is also injecting in your application production environment, those from your linked add-ons.

To access environment variables from your code, just get them from the environment with PATH: os.Getenv("MY_VARIABLE").

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:

   1. git+ssh://[email protected]/<your_app_id>.git
   2. 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 git deployments for more details.

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.