[Fixed]-How to dynamically add EC2 ip addresses to Django ALLOWED_HOSTS

Accepted answer was working fine with IMDSv1. In 2019 AWS launched IMDSv2 which requires session token authentication. Therefore, before requesting instance meta data we first need to fetch the token:

import requests

try:
    IMDSv2_TOKEN = requests.put('http://169.254.169.254/latest/api/token', headers={
        'X-aws-ec2-metadata-token-ttl-seconds': '3600'
    }).text
    EC2_PRIVATE_IP = requests.get('http://169.254.169.254/latest/meta-data/local-ipv4', timeout=0.01, headers={
        'X-aws-ec2-metadata-token': IMDSv2_TOKEN
    }).text
except requests.exceptions.RequestException:
    EC2_PRIVATE_IP = None


ALLOWED_HOSTS = [
    'my-app-test.eu-central-1.elasticbeanstalk.com'
]

if EC2_PRIVATE_IP:
    ALLOWED_HOSTS.append(EC2_PRIVATE_IP)

References:

https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/configuring-instance-metadata-service.html
https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instancedata-data-retrieval.html

The snippets below will find either the Public IP address or the Elastic IP address associated with your EC2 instance and append it to ALLOWED_HOSTS.

• Install PyCurl

  pip install pycurl
  

• Python 3

  import pycurl
  from io import BytesIO
  
  # Determine Public IP address of EC2 instance
  buffer = BytesIO()
  c = pycurl.Curl()
  c.setopt(c.URL, 'checkip.amazonaws.com')
  c.setopt(c.WRITEDATA, buffer)
  c.perform()
  c.close()
  # Body is a byte string, encoded. Decode it first.
  ALLOWED_HOSTS.append(buffer.getvalue().decode('iso-8859-1').strip())
  

• Python 2

  import pycurl
  from StringIO import StringIO
  
  buffer = StringIO()
  c = pycurl.Curl()
  c.setopt(c.URL, 'checkip.amazonaws.com')
  c.setopt(c.WRITEDATA, buffer)
  c.perform()
  c.close()
  # In Python 2, we can cast the return value to
  # string without knowing the exact encoding.
  ALLOWED_HOSTS.append(str(buffer.getvalue()).strip())