proxyprefix

Let a proxied service know how it should construct URLs in the response.

This is achieved using a WSGI middleware that prefixes SCRIPT_NAME with an X-Forwarded-Prefix header if present.

It will also update the WSGI environ to set wsgi.url_scheme and HTTPS according to the X-Forwarded-Proto header if present.

Example

Let's say:

curl https://service.com/posts/

responds with:

{
    "posts": [...],
    "next": "https://service.com/posts/?page=2"
}

If we put service behind a proxy at http://client.com/service/, we want to make the following changes to that next URL:

1. The host name should be client.com instead of service.com.
2. The protocol should be http instead of https.
3. The path should start with /service/.

If you're using django, you can do all three by setting settings.USE_X_FORWARDED_HOST to True, installing the proxyprefix WSGI middleware, and making sure your proxy sends these headers with its request to service:

curl \
  --header "X-Forwarded-Host: client.com" \
  --header "X-Forwarded-Proto: http" \
  --header "X-Forwarded-Prefix: /service/" \
  https://service.com/posts/

Which gives you a response with links to the proxy, not the service:

{
    "posts": [...],
    "next": "http://client.com/service/posts/?page=2"
}

Installation

pip install proxyprefix

from proxyprefix.wsgi import ReverseProxiedApp

# flask example:
app.wsgi_app = ReverseProxiedApp(app.wsgi_app)

# django example:
application = ReverseProxiedApp(get_wsgi_application())

Sending X-Forwarded-* headers in local development

If you use djproxy to proxy services in local development, it will send X-Forwarded-Host and X-Forwarded-Proto for you. But X-Forwarded-Prefix is a non-standard header, so you will need to use the middleware provided by proxyprefix:

from djproxy.urls import generate_routes

configuration = {
    'service_name': {
        'base_url': 'https://service.com/',
        'prefix': '/service_prefix/',
        'append_middlware': ['proxyprefx.contrib.djproxy.XForwardedPrefix']
    }
}

urlpatterns += generate_routes(configuration)

Middleware support was added in djproxy 2.0.0.

Development

Clone the project and install requirements:

pip install -r requirements.txt

Run the tests with nosetests:

nosetests

You can lint and test files when they change automatically using testtube:

stir