Error R10 when deploying the API using AdonisJS on Heroku - node.js

Question

Here is the error:
Error R10 (Boot timeout) -> Web process failed to bind to $PORT within 60 seconds of launch
Analyzing the log, I noticed that every time I 'run' the app on Heroku it directs to a different port.
I have already encountered numerous examples of how to solve this, but using Express and not explicitly using AdonisJS (which I am finding very limited).
Another issue I have is the use of the domain for my application, should the be the same as the Heroku provides or localhost (127.0.0.1)?
My log:
2019-03-28T12:54:19.688098+00:00 app[web.1]: info: serving app on http://127.0.0.1:48470
2019-03-28T12:55:17.075091+00:00 heroku[web.1]: State changed from starting to crashed
2019-03-28T12:55:17.081028+00:00 heroku[web.1]: State changed from crashed to starting
2019-03-28T12:55:16.883066+00:00 heroku[web.1]: Error R10 (Boot timeout) -> Web process failed to bind to $PORT within 60 seconds of launch
2019-03-28T12:55:16.883174+00:00 heroku[web.1]: Stopping process with SIGKILL
2019-03-28T12:55:17.056876+00:00 heroku[web.1]: Process exited with status 137
2019-03-28T12:55:20.176409+00:00 heroku[web.1]: Starting process with command `ENV_SILENT=true npm start`
2019-03-28T12:55:22.553527+00:00 app[web.1]:
2019-03-28T12:55:22.553548+00:00 app[web.1]: > adonis-api-app#4.1.0 start /app
2019-03-28T12:55:22.553551+00:00 app[web.1]: > node server.js
2019-03-28T12:55:22.553552+00:00 app[web.1]:
2019-03-28T12:55:23.598805+00:00 app[web.1]: info: serving app on http://127.0.0.1:37943
2019-03-28T12:56:20.763929+00:00 heroku[web.1]: State changed from starting to crashed
2019-03-28T12:56:20.660053+00:00 heroku[web.1]: Error R10 (Boot timeout) -> Web process failed to bind to $PORT within 60 seconds of launch
2019-03-28T12:56:20.660202+00:00 heroku[web.1]: Stopping process with SIGKILL
2019-03-28T12:56:20.747895+00:00 heroku[web.1]: Process exited with status 137
2019-03-28T12:56:23.940320+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/" host=***** protocol=https
2019-03-28T13:21:40.085858+00:00 heroku[web.1]: State changed from crashed to starting
2019-03-28T13:21:43.920685+00:00 heroku[web.1]: Starting process with command `ENV_SILENT=true npm start`
2019-03-28T13:21:46.419408+00:00 app[web.1]:
2019-03-28T13:21:46.419429+00:00 app[web.1]: > adonis-api-app#4.1.0 start /app
2019-03-28T13:21:46.419431+00:00 app[web.1]: > node server.js
2019-03-28T13:21:46.419433+00:00 app[web.1]:
2019-03-28T13:21:47.899057+00:00 app[web.1]: info: serving app on http://127.0.0.1:51104
My .env file:
HOST=127.0.0.1
PORT=8080
NODE_ENV=development
APP_NAME=AdonisJs
APP_URL=https://${HOST}:${PORT}
APP_KEY=*******
How to prevent the port from being changed?

Answer 1

There are a few things going on here.
Configuration from the environment
There are two main benefits to configuring your application from the environment:
It makes configuration environment-specific, e.g. so you can use different databases, mail servers, etc. in development from the ones you use in production
It lets you keep sensitive values like API keys and passwords out of your codebase
Including your .env file in your repository negates both of these benefits. It's fine to use one in development, and it can be a convenient way to set environment variables, but it shouldn't be committed to your repository or used in Heroku.
Heroku natively supports configuration from the environment. You can set variables in the web UI or via heroku:config on the command line. This is where your environment variables should go in production.
I strongly urge you to remove your .env file from your repository with
git rm --cached .env
add it to your .gitignore, and use Heroku's native environment-based configuration instead. You should also invalidate any API keys or passwords that are contained in that file and generate new ones.
For what it's worth, the AdonisJS documentation agrees with this approach:
The .env file should never be committed to your source control or shared with other people.
Different ports
This is entirely expected:
On Heroku, apps are completely self-contained and do not rely on runtime injection of a webserver into the execution environment to create a web-facing service. Each web process simply binds to a port, and listens for requests coming in on that port. The port to bind to is assigned by Heroku as the PORT environment variable.
Heroku tells you which port to bind to via the PORT environment variable, and you must use it. But this isn't the port that will be visible externally; the standard HTTP ports will be routed to your application automatically.
IP addresses
Your application should listen on all IP addresses. If you're using Express, I think that means you don't provide an IP address in your .listen() call. You should only provide the port there, and that port should come from the PORT environment variable.