502 error deploying flask application to elastic beanstalk using CLI

Question

Running into an issue with deploying a very straight-forward Hello, World type flask application to AWS Elastic Beanstalk. I'm using the eb CLI tool, installed on Mac with brew and python 3. Some sample code below:

from flask import Flask

app = Flask(__name__)

@app.route('/')
def hello_world():
    return 'Hello, World!'

@app.route('/<username>')
def hello_user(username):
    return f'Hello, {username}!'

# run the app.
if __name__ == "__main__":
    # Setting debug to True enables debug output. This line should be
    # removed before deploying a production app.
    
    app.debug = True
    app.run(port=8000)

It runs locally as expected, and I can deploy it through the CLI, but when I go to access the application I'm getting a 502 Bad Gateway.

I've tried:

• Accessing the application using both the URL from the console, and also eb open .
• Specifying the port 5000 (default flask) and 8000 at the end of the URL.
• Using app.run() , and app.run(port=8000) with no success.

I've had a look through the documentation but couldn't find a fix. If folks have any suggestions or links they think would be helpful that'd be appreciated.

Answer 1

Your application should be called application not app .

Below is the corrected application.py file. I verified that it works using Python 3.7 running on 64bit Amazon Linux 2/3.1.0 platform:

from flask import Flask

application = Flask(__name__)

@application.route('/')
def hello_world():
    return 'Hello, World!'

@application.route('/<username>')
def hello_user(username):
    return f'Hello, {username}!'

# run the app.
if __name__ == "__main__":
    # Setting debug to True enables debug output. This line should be
    # removed before deploying a production app.
    
    application.debug = True
    application.run(port=8000)