I was about to suggest a similar UX for expressing a list of route
services, by relying on params ordering

cf update-route DOMAIN [-n HOST] (-s 'service instance' )*
cf update-route DOMAIN [-n HOST] -s caching -s https-only -s rate-limiting

Besides, If the MVP does not include support for multiple route services,
route service implementers might be able to experiment with supporting
arbitrary params as a way for users to specify fine grain options, possibly
ordered

cf create-service large-grain-route-service -p '{ "caching": true,
"ssl_only": true, "rate_limit": 3 }'

+1 for Mike's suggestions to allow for some route services to be
implemented in an upfront LB such as no router. This might address the
latency and availability concerns in the initial MVP ("route services to
forward requests back through the LB and GoRouter")

Lastly, it seems important that route services be able to output logs that
end up being associated with the app that receive the associated traffic
(e.g. cache hit or cache miss for a specific incoming request). With route
services being associated to routes (and not being bound to app instances
anymore), I'd like to re-iterate the suggestion I made in the design
document (on Feb 17) to have the gorouter include the app_id in the headers
of the signed request it sends to route service(s). This will allow for a
route service with log_emiter scope to add entries to the proper app
through loggregator/doppler. Of course, this also means that when a route
is associated to multiple apps, the load balancing decision among app is
made prior to sending traffic to route service(s). I'd imagine the app_id
could be propagated in the signed request headers when going through route
services and finally reaching the gorouter before hitting the app (as to
preserve the stateless nature of gorouter).

Guillaume.


On Fri, Jun 26, 2015 at 12:04 AM, Shannon Coen <scoen(a)pivotal.io> wrote:

This is great. Thank you, Mike.

FWIW, James had the following suggestion update-route could be used to
associate multiple routes, and express their chain order. We're not fixed
on this UX. We'll consider this more carefully when we get closer to the CF
CLI work.

cf update-route DOMAIN [-n HOST] [-s 'list,of,service,instances']

Shannon Coen
Product Manager, Cloud Foundry
Pivotal, Inc.

On Thu, Jun 25, 2015 at 12:58 PM, Mike Youngstrom <youngm(a)gmail.com>
wrote:

This is interesting. Could you flesh this out for me? What use cases do
you have in mind for associating a service instance with a route, but not
providing a forwarding address?

I would imagine you could bind a service to a route any time you want to
customize incoming traffic in some way. But that customization wouldn't
necessarily have to be implemented as a proxy.

Here are a few examples:

* A Public facing service as an indicator that a given route should be
made public facing. (Would require a broker to orchestrate stuff outside
of CF DNS, applying DoS security profiles to the route, force ssl on the
front end load balancer, etc.)
* A service to apply web front caching to a route. Could be done as a
proxy but could also be done by changing config in a front end load
balancer that supports caching like an F5 LTM.
* Rate limiting. Could be implemented as a proxy, or could be
implemented by applying some config in a front end load balancer
* A security service to limit client IP addresses allowed to connect on
a route. Again could be implemented as a proxy if you trust
X-Forwarded-For or simply change some config on a front end load balancer
no new proxy needed.

Basically a service applied to a route could trigger and manage all
kinds of functionality not necessarily implemented as proxy orchestrated by
the GoRouter.

It also occurs to me that the only time chain ordering of route services
seems to be an issue is in the case of a proxy url. So, it is unfortunate
that I'd be limited to binding only one route service when I may want to
apply all kinds of functionality to a route not implemented as a proxy
because user defined ordering isn't an issue.

That said I can see how it can be difficult for CF to provide a generic
solution to the kind of functionality applied above and that you may not
want to distract from the basic Route Services MVP to accommodate these
types of use cases. I guess I can only hope that you keep the concept of
applying non proxy functionality to a route in mind as you move through
your MVP.

Mike

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