Why am I getting a Deploy Error: Health Checks?

In general, when App Platform attempts to deploy your application it will run some automated health checks to make sure your app started correctly before sending web traffic to it. You can configure these checks, but by default they’re just checking to see if your app is listening on port 8080.

So the most common reason for this error, especially with a new app, is a misconfigured port.

App Platform expects that any Service you deploy will listen on all interfaces on port 8080 (0.0.0.0:8080). If you cannot modify your Service’s code to listen on port 8080, you can configure App Platform to expect a different port. This can be done during initial App creation or on the Component details page of your Service after your App has been created. If you’re configuring your application via App Spec, you can use the http_port key to set App Platform to expect your Service on a different port.

For convenience, App Platform will set an environment variable named PORT in your runtime environment that contains the expected port number for your Service to listen on.

Had the same issue while using Nuxt.js and deploying as an app. I added this to nuxt.config.js:

server: {
  port: process.env.PORT,
  host: process.env.HOST
}

Leaving the default HTTP port in DigitalOcean, but adding an env var in the component configuration HOST=0.0.0.0. This lets me work locally via .env and on DigitalOcean without hardcoding anything.