ExpressJS - Presets

Start a Express.js Project with Docker in 2 Easy Steps

  1. Run kool create expressjs my-project
  2. Run kool run setup

Yes, using kool + Docker to create and work on new Express.js projects is that easy!

If you haven't done so already, you first need to install Docker and the kool CLI.

Also, make sure you're running the latest version of kool. Run the following command to compare your local version of kool with the latest release, and, if a newer version is available, automatically download and install it.

$ kool self-update

Please note that it helps to have a basic understanding of how Docker and Docker Compose work to use Kool with Docker.

Use the kool create PRESET FOLDER command to create your new Express.js project:

$ kool create expressjs my-project

Under the hood, this command will create a "Hello world!" app.js file in the root of your new project directory.

After installing Express.js, kool create automatically runs the kool preset expressjs command, which helps you easily set up the initial tech stack for your project using an interactive wizard.

$ Preset expressjs is initializing! ? Which javascript package manager do you want to use [Use arrows to move, type to filter] > npm yarn $ Preset expressjs initialized!

Now, move into your new Node.js project:

$ cd my-project

The kool preset command auto-generated the following configuration files and added them to your project, which you can modify and extend.

+docker-compose.yml +kool.yml

Now's a good time to review the services added to the docker-compose.yml file.

Say hello to kool.yml, say goodbye to custom shell scripts!

As mentioned above, the kool preset command added a kool.yml file to your project. Think of kool.yml as a super easy-to-use task helper. Instead of writing custom shell scripts, add your own scripts to kool.yml (under the scripts key), and run them with kool run SCRIPT (e.g. kool run npm). You can add your own single line commands (see npm below), or add a list of commands that will be executed in sequence (see setup below).

To help get you started, kool.yml comes prebuilt with an initial set of scripts (based on the preset), including a script called setup, which helps you spin up a project for the first time.

scripts: node: kool exec app node npm: kool exec app npm # or yarn npx: kool exec app npx setup: - kool docker kooldev/node:20 npm install - kool start # - add more setup commands

Go ahead and run kool run setup to start your Docker environment and finish setting up your project:

$ kool run setup

As you can see in kool.yml, the setup script will do the following in sequence: run npm install to build your Express packages and dependencies (by spinning up and down a temporary Node container); and then start your Docker environment using docker-compose.yml (which includes a command to automatically run node app.js).

Once kool run setup finishes, you should be able to access your new site at http://localhost:3000 and see the "Hello world!" page. Hooray!

Verify your Docker container is running using the kool status command:

$ kool status +---------+---------+-------------------------------------------+--------------+ | SERVICE | RUNNING | PORTS | STATE | +---------+---------+-------------------------------------------+--------------+ | app | Running |>3000/tcp, :::3000->3000/tcp | Up 4 seconds | +---------+---------+-------------------------------------------+--------------+

Run kool logs app to see the logs from the running app container, and confirm the Node.js server was started.

Use kool logs to see the logs from all running containers. Add the -f option after kool logs to follow the logs (i.e. kool logs -f app).

$ kool logs app Attaching to my-project_app_1 app_1 | Server running at http://localhost:3000/

Use kool exec to execute a command inside a running service container:

# kool exec [OPTIONS] SERVICE COMMAND [--] [ARG...] $ kool exec app node -v

Try kool run node -h to execute the kool exec app node -h command in your running app container and print out information about Node.js.

Similar to SSH, if you want to open a Bash session in your app container, run kool exec app bash, where app is the name of the service container in docker-compose.yml. If you prefer, you can use sh instead of bash (kool exec app sh).

$ kool exec app bash bash-5.1# $ kool exec app sh /app #

If you need your app container to use your local SSH keys to pull private repositories and/or install private packages (which have been added as dependencies in your package.json file), you can simply add $HOME/.ssh:/home/kool/.ssh:delegated under the volumes key of the app service in your docker-compose.yml file. This maps a .ssh folder in the container to the .ssh folder on your host machine.

volumes: - .:/app:delegated + - $HOME/.ssh:/home/kool/.ssh:delegated

When it's time to stop working on the project:

$ kool stop

And when you're ready to start work again:

$ kool start

We have more presets to help you start projects with kool in a standardized way across different frameworks.

Missing a preset? Make a request, or contribute by opening a Pull Request. Go to and browse the code to learn more about how presets work.
By choosing "Accept all cookies" you agree to the use of cookies to help us provide you with a better user experience and to analyse website usage. Only the essential cookies are necessary for the proper functioning of our website and cannot be refused.
Check out our Cookie Policy and Privacy Policy for more information.