Start Commands
The Start command is the command needed to start your application. It’s a must for any application, whether it’s created with a Nixpack, Buildpack, or Dockerfile. The Start command may differ depending on the application’s language. We’ve provided examples from some common languages below.
Start command from a Nixpack
When an application is created with a Nixpack, we attempt to infer the Start command based on the contents of your application’s repository, or you can specify the Start command in the Resources step when you add the application.
Start command from a Buildpack
When an application is created with a Buildpack, we attempt to infer the Start command based on the contents of your application’s repository, or you can specify the Start command in the Resources step when you add the application.
Start command from a Docker image or Dockerfile
If your application uses a Docker image or Dockerfile to set up your container image, you must specify the ENTRYPOINT or CMD instruction in the Dockerfile to run a container. For more information about how to specify your application’s instructions, see the Dockerfile reference or Best practices for writing Dockerfiles.
Chaining commands
To add multiple Start commands, use && to chain the commands together like:
command one && command two
The Start command needs to always initiate a web service as the last command. That will keep the container running and listening to incoming connections.Each command must successfully execute (exit with code 0) for the next command to run.
View or edit the start command
Go to Processes > Runtime processes and edit the Web process to change the Start command. The application will automatically deploy with the updated Start command.
Start command language examples
Python
Python
python3 main.py
Django
gunicorn .wsgi
Go
bin/<repo name>
PHP
PHP
heroku-php-apache2
Laravel
heroku-php-apache2 /public
php artisan serve --host 0.0.0.0 --port 8080
Statamic
heroku-php-apache2 public/
Node.js
Node.js
npm start
If you would like to use another command, you need to modify the web process in Sevalla.
"scripts": {
"start": "node server.js"
},
Node.js with a Dockerfile
When you create the app Sevalla creates a process from the CMD instruction.
CMD ["npm", "run", "start"]
If you change this command in the repository, the process is not changed by default, so you must edit the process in your application’s Processes in Sevalla.
Ruby
Ruby on Rails
rails server
Ruby on Rails with a Dockerfile
When you first create the application, Sevalla creates a process from the ENTRYPOINT instruction.
ENTRYPOINT ["entrypoint.sh"]
If you change this command in the repository, the process is not changed by default, so you must edit the process in your application’s Processes in Sevalla.
Java
When you deploy an application, Sevalla automatically creates processes based on the Procfile in the root of the repository.
Scala
target/universal/stage/bin/ -Dhttp.port=$PORT