访问 Heroku 部署的 Flask 应用程序时出错

Question

I have a very, very simple Flask app that I'm testing on Heroku just to see if it works. I've tried connecting it to my GitHub repo and using Heroku CLI but neither changes the outcome.

from flask import Flask

app = Flask("__name__")


@app.route("/api", methods=["GET"])
def get():
    return {"success": "much success"}


app.run(debug=True)

I followed a tutorial on Udemy on deploying to Heroku but it's not working. I was told to add these files to my root:

// runtime.txt
python-3.8.3

// requirements.txt
// created by running pip3 freeze > requirements.txt
// manually added 'uwsgi'
appdirs==1.4.3
attrs==19.3.0
black==19.10b0
click==7.1.1
Flask==1.1.2
gunicorn==20.0.4
itsdangerous==1.1.0
Jinja2==2.11.2
MarkupSafe==1.1.1
pathspec==0.8.0
regex==2020.4.4
toml==0.10.0
typed-ast==1.4.1
Werkzeug==1.0.1
uwsgi

// uwsgi.ini
[uwsgi]
http-socket = :$(PORT)
master =true
die-on-term = true
module = app:app 
memory-report = true

// Procfile
web: uwsgi uwsgi.ini

I get an 'Application Error' when I visit my app on Heroku. This is what Heroku logs shows:

2020-04-20T20:32:57.218876+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/favicon.ico" host=ninny-code-flask.herokuapp.com request_id=d355b4b9-c532-4971-91fa-e3421ca98971 fwd="104.178.145.19" dyno= connect= service= status=503 bytes= protocol=https

Answer 1

I think you are missing the PORT which you need to assigning using the env variable $PORT (provided by Heroku)

app.run(debug=False, port=int(os.environ.get("PORT", 5000)), host='0.0.0.0')

Answer 2

Looking at your debug output, I see that the script is exiting/crashed due to the port already in use. Check if you have any other local server running on the same port on the command line or service. See this line? it tells you what's the reason it failed.

OSError: [Errno 98] Address already in use

Find the pid process and shut it down/terminate it. There must be another process listening on the port. You might find out that process by using the following command:

$ lsof -i :5000

and then run sudo to kill the process.

sudo kill -9 <process_id>

However, I see now Error code h10 in heroku logs.

This error is thrown if in a Node. js environment, you forget to set a start script. Heroku uses this script to start your app so if it is missing, it would throw an H10-App crashed error code message.

Check your Procfile file, look up for spacing errors.

Wrong web : node server.js
Correct web:node server.js