Handling EC2 ELB health checks and Django's ALLOWED_HOSTS setting.

settings.py

# Hosts/domain names that are valid for this site; required if DEBUG is False
# See https://docs.djangoproject.com/en/1.5/ref/settings/#allowed-hosts
ALLOWED_HOSTS = [
    'yourdomain.tld',
    '.compute-1.amazonaws.com', # allows viewing of instances directly
]

import requests
EC2_PRIVATE_IP  =   None
try:
    EC2_PRIVATE_IP  =   requests.get('http://169.254.169.254/latest/meta-data/local-ipv4', timeout = 0.01).text
except requests.exceptions.RequestException:
    pass

if EC2_PRIVATE_IP:
    ALLOWED_HOSTS.append(EC2_PRIVATE_IP)

To answer @jameserrico above:

The Elastic Load Balancer HTTP health check will use the instance's internal IP [for the host header].

(From https://forums.aws.amazon.com/thread.jspa?messageID=423533)

Works great! thanks!

Still works!

put your ec2 instance's private ip in allowed hosts if using single instance

you do not need line 5 '.compute-1.amazonaws.com'. Works fine also without it.
Also the public-hostheader (@JoarLeth) is not required.

Right on, good looks bud 👍

This is a great solution, congrats

how about v6 addresses?

Another option is to implement a middleware that returns a health check before Django's SecurityMiddleware (that checks the request against ALLOWED_HOSTS): https://gist.github.com/mgax/cf771b1991e68ca454693d5f3597ff04

Hi, I am stuck with this we have an ELB which uses the Round-Robin technique and we have 3-10 servers, and I couldn't get any single of them working. Which IP shall I put into the below line 11
EC2_PRIVATE_IP = requests.get('http://169.254.169.254/latest/meta-data/local-ipv4', timeout = 0.01).text

Please someone help me here

This Works for me

import requests

ALLOWED_HOSTS = [
    'yourdomain.tld',
    '.compute-1.amazonaws.com', # allows viewing of instances directly
]

EC2_PRIVATE_IP = None

try:
    token = requests.put("http://169.254.169.254/latest/api/token",
                         headers={"X-aws-ec2-metadata-token-ttl-seconds": "21600"}).text
                         
    EC2_PRIVATE_IP = requests.get("http://169.254.169.254/latest/meta-data/local-ipv4",
                                  headers={"X-aws-ec2-metadata-token": token}, timeout=0.01).text
                                  
except requests.exceptions.RequestException:
    pass

if EC2_PRIVATE_IP:
    ALLOWED_HOSTS.append(EC2_PRIVATE_IP)

Great,
I also have somewhat similar try/except block.