如何使用弹性 beantalk 和 aws 修复 Flask 应用程序中的内部服务器错误

Question

When I run my flask application locally, I can connect to MySQL RDS just fine. However, when I try to deploy the app using Elastic Beanstalk, I get a "500 Internal Server Error". I do not know if this helps or not, but when I use a local sqlite file, my application works as intended both when ran locally and when deployed with Elastic Beanstalk.

I did try and work along with this page, but I did not notice any difference when I included the environment properties. https://docs.aws.amazon.com/elasticbeanstalk/latest/dg/create-deploy-python-rds.html#python-rds-create

Here is my __init__.py file. I just comment out whichever database URI I do not wish to use when testing.

from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_bcrypt import Bcrypt
from flask_login import LoginManager

application = Flask(__name__)
application.config['SECRET_KEY'] = 'c4633b5a978d282104dbc44c32c9486'
application.config['SQLALCHEMY_DATABASE_URI'] =  
'mysql+pymysql://<username>:<password>@garbagero.cuz5hqf0nh5m.us-east- 
2.rds.amazonaws.com/ebdb'
#application.config['SQLALCHEMY_DATABASE_URI'] =  'sqlite:///site.db'
db = SQLAlchemy(application)
bcrypt = Bcrypt(application)
login_manager = LoginManager(application)
login_manager.login_view = 'login'
login_manager.login_message_category = 'info'

from garbageRO import routes

EDIT: I finally figured out that I accidentally left 1 package out of my requirements.txt file. I thought I had already double checked this before posting but apparently I did not.

Answer 1

I do recommend that you debug your application using the verbose mode of Flask and SQLAlchemy, so you can better know whats going on, with this level or detail i can only suggest something to check like the permissions/IAM on AWS, to check if your ElasticBeanstalk can really access the RDS, im assuming the ELB/applcation use a set of credentials, and you tested locally with another credentials, right?

About the "verbose mode", try setting the SQLALCHEMY_ECHO to True: http://flask-sqlalchemy.pocoo.org/2.3/config/ There's also this option ive not tested: https://github.com/pallets/flask-sqlalchemy/pull/208/files?short_path=fd40cf2

And on the Flask app you can set debug to True also.

Another option, is to debug if you can connect on the RDS directly with a client on the machine/container, or a least if a telnet is working.