Run Flask App with Let's Encrypt SSL Certificate
2 min read
Flask supports serving in HTTPS mode when provided with valid certificate and key file. I have been using Let's Encrypt which automatically manages all the SSL keyfiles and certificates used on my server. I had troubles setting up preconfigured SSL keys and certificates with my Flask app. Although I had it figured out later.
What you need to do is provide an
ssl_context option with the Flask app which requires 2 things. One is the issued SSL certificate and the other is the key file. Let's Encrypt puts them all in
/etc/letsencrypt/live/yourdomain.com. So you need to find the correct one and set it up with Flask. Here is my setup.
import requests from flask import Flask, request app = Flask(__name__) def serve(): return "Hello world", 200 if __name__ == '__main__': app.run(host="0.0.0.0", port=8080, ssl_context=('/etc/letsencrypt/live/mdminhazulhaque.io/fullchain.pem', '/etc/letsencrypt/live/mdminhazulhaque.io/privkey.pem'))
As you can see,
fullchain.pem is the certificate and
privkey.pem is the keyfile. So I ran the above example and checked if the SSL is working with
openssl s_client -quiet -connect mdminhazulhaque.io:8080
depth=2 O = Digital Signature Trust Co., CN = DST Root CA X3 verify return:1 depth=1 C = US, O = Let's Encrypt, CN = Let's Encrypt Authority X3 verify return:1 depth=0 CN = mdminhazulhaque.io verify return:1 read:errno=0
errno=0 which means Flask is working fine with SSL. :D