Route Services

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This topic provides guidance for offering a service to a Cloud Foundry (Cloud Foundry) services marketplace. For information about consuming these services, see Manage App Requests with Route Services.

Note: Route services require Diego. Your deployment must use the Diego architecture or you must enable Diego for your app.

Introduction

Cloud Foundry app developers might want to apply transformation or processing to requests before they reach an app. Common examples of use cases include authentication, rate limiting, and caching services. Route services are a kind of Marketplace service that you can use to apply various transformations to app requests by binding an app’s route to a service instance. Through integrations with service brokers and, optionally, with the Cloud Foundry routing tier, providers can offer these services with a familiar, automated, self-service, and on-demand user experience.

Architecture

Cloud Foundry supports the following models for route services:

• Fully-brokered services
• Static, brokered services
• User-provided services

In each model, you configure a route service to process traffic addressed to an app.

Fully-Brokered Service

In the fully-brokered service model, the Cloud Foundry router receives all traffic to apps in the deployment before any processing by the route service. You can bind a route service to any app, and if an app is bound to a route service, the Cloud Foundry router sends its traffic to the service. After the route service processes requests, it sends them back to the load balancer in front of the Cloud Foundry router. The second time through, the Cloud Foundry router recognizes that the route service has already handled them, and forwards them directly to app instances.

The route service can run inside or outside of Cloud Foundry, so long as it fulfills the Service Instance Responsibilities to integrate it with the Cloud Foundry router. A service broker publishes the route service to the Cloud Foundry marketplace, and makes it available to developers. You can then create an instance of the service and bind it to your apps with the following commands:

cf create-service BROKER-SERVICE-PLAN SERVICE-INSTANCE

cf bind-route-service YOUR-APP-DOMAIN SERVICE-INSTANCE [--hostname HOSTNAME] [--path PATH]

You can configure the service either through the service provider web interface or by passing arbitrary parameters to their cf create-service call through the -c flag.

Advantages:

• You can can use a Service Broker to dynamically configure how the route service processes traffic to specific apps.

• Adding route services requires no manual infrastructure configuration.

• Traffic to apps that do not use the service makes fewer network hops because requests for those apps do not pass through the route service.

Disadvantages:

• Traffic to apps that use the route service makes additional network hops, as compared to the static model.

Static, Brokered Service

In the static brokered service model, an operator installs a static routing service, which might be a piece of hardware, in front of the load balancer. The routing service runs outside of Cloud Foundry and receives traffic to all apps running in the Cloud Foundry deployment. The service provider creates a service broker to publish the service to the Cloud Foundry marketplace. As with a fully-brokered service, a developer can use the service by instantiating it with cf create-service and binding it to an app with cf bind-route-service.

In this model, you configure route services on an app-by-app basis. When you bind a service to an app, the service broker directs the routing service to process that app’s traffic rather than pass the requests through unchanged.

Advantages:

• You can use a service broker to dynamically configure how the route service processes traffic to specific apps.

• Traffic to apps that use the route service takes fewer network hops.

Disadvantages:

• Adding route services requires manual infrastructure configuration.
• Traffic to apps that do not use the route service make unnecessary network hops. Requests for all apps hosted by the deployment pass through the route service component.

User-Provided Service

If a route service is not listed in the Cloud Foundry marketplace by a broker, you can still bind it to your app as a user provided service. The service can run anywhere, either inside or outside of Cloud Foundry, but it must fulfill the integration requirements described in Service Instance Responsibilities. The service also needs to be reachable by an outbound connection from the Cloud Foundry router.

This model is identical to the fully brokered service model, except without the broker. You can configure the service manually, outside of Cloud Foundry. You can then create a user provided service instance and bind it to your app with the following commands,that supply the URL of their route service:

cf create-user-provided-service SERVICE-INSTANCE -r ROUTE-SERVICE-URL

cf bind-route-service DOMAIN SERVICE-INSTANCE [--hostname HOSTNAME]

Advantages:

• Adding route services requires no manual infrastructure configuration.
• Traffic to apps that do not use the service makes fewer network hops because requests for those apps do not pass through the route service.

Disadvantages:

• You must manually provision and configure route services out of the context of Cloud Foundry because no service broker automates these operations.
• Traffic to apps that use the route service makes additional network hops, as compared to the static model.

Architecture Comparison

The previous models require the broker and service instance responsibilities summarized in the following table:

Enabling Route Services in Cloud Foundry

To begin support for route services in a Cloud Foundry deployment, the operator must provide a passphrase used by the Gorouter to encrypt a header that is sent with the request to the route service. The Gorouter uses this header to validate the request sent by the route service to the app route. The passphrase is configured in the cf-release manifest.

properties
  router:
    route_services_secret: YOUR-SECRET-PASSPHRASE

Note: The route_services_secret property can be a robust passphrase. For more information, see the Gorouter spec in the cf-release repository on GitHub.

Route service instances can send requests to the value of x-cf-forwarded-url, obeying the scheme. The scheme is https by default. For environments that do not support TLS termination, this property can be set to false.

properties:
  router:
    route_services_recommend_https: true

The Gorouter only forwards requests to route services over SSL. By default, certificates provided by route services must be signed by a trusted CA. If they are not, the Gorouter rejects the request. In development environments, this concern might be unreasonable. To deactivate SSL certificate validation, edit the following property:

properties:
  router:
    ssl_skip_validation: true

Service Instance

The following applies only when a broker returns route_service_url in the bind response.

How It Works

Binding a service instance to a route associates the route_service_url with the route in the Cloud Foundry router. All requests for the route are proxied to the URL specified by route_service_url.

The Cloud Foundry router includes the X-CF-Forwarded-Url header containing the originally requested URL, as well as the X-CF-Proxy-Signature and X-CF-Proxy-Metadata headers used by the router to validate that the route-service sent the request. These headers are described in the Headers section.

Service Instance Responsibilities

The route service must handle requests by either:

• Accepting the request, making a new request to the original requested URL, or to another location, and then responding to the original requestor.
• Rejecting the request by responding with a non 2xx HTTP status code.

When forwarding a request to the originally requested URL, the route service must forward the X-CF-Forwarded-Url, X-CF-Proxy-Signature and X-CF-Proxy-Metadata headers on the request or it is rejected. When forwarding a request to a location other than the originally requested URL, the route service strips these headers.

Headers

The following HTTP headers are added by the Gorouter to requests forwarded to route services.

X-CF-Forwarded-Url

The X-CF-Forwarded-Url header contains the originally requested URL. The route service might choose to forward the request to this URL or to another.

X-CF-Proxy-Signature

When the Gorouter receives a request with this header, it accepts and forwards the request to the app only if the URL of the request matches the one associated with the token, if the request was received on time. Otherwise, the request is rejected.

X-CF-Proxy-Signature also signals to the Gorouter that a request has transited a route service. If this header is present, the Gorouter does not forward the request to a route service. The route-service needs to forward these headers in subsequent requests to the orignal requested URL, so that it knows not to send the request back to the route service but to the app. The headers must NOT be sent in the HTTP response to the GoRouter, only in the new HTTP request to the GoRouter.

Note: The X-CF-Proxy-Signature header is an access token. Anyone possessing your X-CF-Proxy-Signature token can bypass the route service. Do not share your your X-CF-Proxy-Signature token with anyone.

CF-hosted Route Services cannot be chained: If the route service forwards the request to a URL to resolve a route for a different app on Cloud Foundry, the route must not have a bound route service. Otherwise, the request is rejected as the requested URL does not match the one in the forwarded X-CF-Proxy-Signature header.

X-CF-Proxy-Metadata

The X-CF-Proxy-Metadata header aids in the encryption and description of X-CF-Proxy-Signature.

SSL Certificates

When Cloud Foundry is deployed in a development environment, certificates hosted by the load balancer are self-signed, and not signed by a trusted Certificate Authority. When the route service finishes processing an inbound request and makes a call to the value of X-CF-Forwarded-Url, be prepared to accept the self-signed certificate when integrating with a non-production deployment of Cloud Foundry.

Timeouts

Route services must forward the request to the app route within the number of seconds configured by the router.route_service_timeout property. The router.route_service_timeout property defaults to 60 seconds.

In addition, all requests must respond in the number of seconds configured by the request_timeout_in_seconds property. The request_timeout_in_seconds property default to 900 seconds.

Timeouts are configurable for the router using the cf-release BOSH deployment manifest. For more information, see the spec.

Broker Responsibilities

Catalog Endpoint

Brokers must include requires: ["route_forwarding"] for a service in the catalog endpoint. If this is not present, Cloud Foundry does not permit users to bind an instance of the service to a route.

Binding Endpoint

When you bind a route to a service instance, Cloud Foundry sends a bind request to the broker, including the route address with bind_resource.route. A route is an address used by clients to reach apps mapped to the route. The broker might return route_service_url, containing a URL where Cloud Foundry proxy requests for the route. This URL must have an https scheme, or the Cloud Controller rejects the binding. route_service_url is optional, and not returning this field allows a broker to dynamically configure a network component already in the request path for the route, requiring no change in the Cloud Foundry router.

For more information about bind requests, see the Binding section of the Open Service Broker API (v2.13) spec on GitHub.

Example Route Services

• Logging Route Service: This route service can be pushed as an app to Cloud Foundry. It fulfills the service instance responsibilities and logs requests received and sent. It can be used to see the route service integration in action by tailing its logs.

• Rate Limiting Route Service: This example route service is a simple Cloud Foundry app that provides rate limiting to control the rate of traffic to an app.

• Various Spring Boot examples.

Tutorial

The following instructions show how to use the Logging Route Service described in Example Route Services to verify that when a route service is bound to a route, requests for that route are proxied to the route service.

For a video of this tutorial, see Route Services in Pivotal Cloud Foundry 1.7 on YouTube.

These commands require the Cloud Foundry Command Line Interface (cf CLI) v6.16 or later.

To use the logging route service:

1. Push the logging route service as an app by running:

   cf push logger
   

2. Create a user provided service instance, and include the route of the logging route service you pushed as route_service_url. Make sure to use https for the scheme.

Run:

```console
cf create-user-provided-service mylogger -r https://logger.cf.example.com
```

1. Push a sample app such as Spring Music. By default, this creates a route spring-music.cf.example.com.

Run:

```
cf push spring-music
```

1. Bind the user provided service instance to the route of your sample app. The bind-route-service command takes a route and a service instance.

The route is specified in the following example by domain cf.example.com and hostname spring-music.

Run:

```console
cf bind-route-service cf.example.com mylogger --hostname spring-music
```

1. Tail the logs for your route service by running:

   cf logs logger
   

2. Send a request to the sample app and view in the route service logs that the request is forwarded to it by running:

   curl spring-music.cf.example.com
   

Security Considerations

The contract between route services and the Gorouter, applicable for fully brokered and user-provided models, activates a Cloud Foundry operator to suggest whether or not requests forwarded from the route service to a load balancer are encrypted. The Cloud Foundry operator makes this suggestion by setting the router.route_services_recommend_https manifest property.

This suggestion does not allow the platform to guarantee that a route service obeys the scheme of the X-Forwarded-Url header. If a route service ignores the scheme and downgrades the request to plain text, a the requester can intercept, and use or edit the data within it.

For increased security, follow these recommendations:

• A load balancer stops TLS and can sanitize and reset X-Forwarded-Proto based on whether the request it received was encrypted or not. Set the router.sanitize_forwarded_proto: false manifest property for the Gorouter.

• A load balancer configured for TCP passthrough can sanitize and reset the header based on whether the request it received was encrypted or not. Set the router.sanitize_forwarded_proto: true manifest property for the Gorouter.

For more information about securing traffic into Cloud Foundry, see Securing Traffic into Cloud Foundry.

Note: When a route service is mapped to a route, the Gorouter sanitizes the X-Forwarded-Proto header once, even though requests pass through the Gorouter more than once.

Recommendations for Securing Route Services

To best secure communications through route services, Cloud Foundry operators :

1. Set the router.route_services_recommend_https: true manifest property.

2. Set the router.disable_http: true manifest property. Setting this property deactivates the HTTP listener, and forces all communication to the Gorouter to be HTTPS. This assumes all route services communicate over HTTPS with the Gorouter. This causes requests from other clients made to port 80 to be rejected. You must confirm that clients of all apps make requests over TLS.

3. Confirm that route services do not change the value of the X-Forwarded-Proto header.