Django Login Issue with Custom Domain on Google Cloud Run

Based on the information provided, your issue appears to be related to cookie domain settings in Django when using a custom domain with Google Cloud Run. This is a common problem when the domain used for accessing the application doesn't match the domain set for cookies.

The Problem

When you access your Django application through your custom domain, the login process fails silently (redirecting back to the login page) because the session cookie isn't being properly set or recognized. This happens because:

1. The login cookie domain doesn't match the domain in your browser
2. Django is likely still using the default Cloud Run URL for cookie settings

Solution

1. Configure SESSION_COOKIE_DOMAIN

In your Django settings, you need to set the SESSION_COOKIE_DOMAIN to match your custom domain:

PYTHONCopied
# settings.py
SESSION_COOKIE_DOMAIN = 'custom-domain.org'  # Replace with your actual domain

This ensures that cookies are set for the correct domain when users access your site through the custom domain.

2. Ensure HTTPS Settings are Properly Configured

Since you're using HTTPS (which is good practice), make sure these settings are enabled:

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# settings.py
CSRF_COOKIE_SECURE = True
SESSION_COOKIE_SECURE = True

These settings prevent cookies from being transmitted over non-secure connections.

3. Check ALLOWED_HOSTS Setting

Ensure your custom domain is included in the ALLOWED_HOSTS setting:

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# settings.py
ALLOWED_HOSTS = ['your-app.run.app', 'custom-domain.org']

4. Consider Using CSRF_TRUSTED_ORIGINS

If you're using Django 4.0+, you might also need to set:

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# settings.py
CSRF_TRUSTED_ORIGINS = ['https://custom-domain.org']

5. For Cloud Run Specific Configuration

When using custom domains with authenticated Cloud Run services, you may need to configure your service to accept your custom domain as a valid authentication audience. This is particularly important if your service uses IAM authentication.

Additional Troubleshooting

If the above solutions don't resolve the issue:

1. Check your browser's developer tools to see if cookies are being set correctly
2. Verify that your custom domain mapping in Cloud Run is properly configured
3. Ensure your application is correctly handling the Host header from requests

By implementing these changes, your Django application should properly handle authentication when accessed through your custom domain.