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  2. feedback request: extracting a common route-registrar job

Re: feedback request: extracting a common route-registrar job

Amit Kumar Gupta
 

Hey all,

The router already has some health check behaviour -- you can naively
register routes with it and it's smart about knowing whether to actually
route traffic or not. I'd like to understand what the specific use cases
are that would require a route-registration job to support additional
custom health check logic provided by the various colocated jobs.

Here's the set of things that are being done/need to be done for this track
of work:

1. extract route-registration process from UAA job in cf-release into its
own job in cf-release (note that the new uaa-release doesn't have this
process) [story done, needs acceptance]
2. use this route-registration job colocated with UAA in the cf manifests.
[story done, needs acceptance]
3. use this route-registration job colocated with CC, HM9k, and doppler in
the cf manifests. [stories in flight]
4. discover additional requirements for a generic route-registration job to
be useful [this email thread]
5. implement features in route-registration job to satisfy requirements
6. wait for consul to be declared stable, and enable the routing-api as a
default part of cf deployments [next couple final versions of cf-release
will validate consul]
7. all things doing route-registration should use routing-api
8. extract route-registration job out of cf-release (and put it where?) in
order to make it usable by other things like Gemfire, MySQL, Riak, etc.
9. discover more additional requirements for a generic route-registration
job to be useful
10. implement more features in route-registration job to satisfy
requirements
11. implement more features in routing-api to satisfy requirements

This isn't necessarily an ordered list, however we want to extract and
start using the route-registration stuff early to discover requirements,
and whether it's even a feasible idea, rather than waiting on consul and
routing-api to validate it. A nice additional consequence of doing this
extraction early is that once we want to switch over to routing-api, it
only needs to be done in one place.

Jens,

Here is a story in the Routing backlog to enable the routing-api to support
sticky-session route registrations:
https://www.pivotaltracker.com/story/show/100327146

Best,
Amit

On Tue, Sep 8, 2015 at 3:43 PM, Lyle Franklin <lfranklin(a)pivotal.io> wrote:

The mysql and riak services register routes with this guy:
https://github.com/cloudfoundry-incubator/route-registrar. At a glance,
the option to run a healthcheck script to determine whether the service was
healthy would be our only real requirement in addition to the routing API
interaction. We'd love to be guinea pigs for any extracted library.

- Lyle

On Tue, Sep 8, 2015 at 1:38 PM, Zach Robinson <zrobinson(a)pivotal.io>
wrote:

i think it's a great idea, but I would wait until the routing api goes
live (waiting on consul stability) and use that tooling to create something
re-usable. I think the job for that could have some sort of health checky
thing where it would run a script with an agreed upon name to decide when
to register/unregister.

-Zach

On Tue, Sep 8, 2015 at 12:53 PM, Amit Gupta <agupta(a)pivotal.io> wrote:

Hi all,

Several components within cf-release, as well as many jobs in different
releases, register a route with the gorouter:

- *doppler* registers the "doppler" and "loggregator" routes
- the *hm9000* API server registers the "hm9000" route
- *UAA* registers "uaa", "*.uaa", "login", and "*.login" routes
- *CC* registers the "api" route
- Many *service brokers* also register a route.

All these components register their routes in different ways. They also
all use the existing NATS flow, and will all need to switch their
implementations to use the routing API once that goes live and we start to
phase out NATS.

We have been working on extracting a route-registrar job which can be
colocated with other jobs and register routes on their behalf. Currently
it naively just always advertises the configured routes, and relies on the
gorouter's behaviour around knowing not to route requests to addresses that
aren't currently up.

One might require more sophisticated logic than this, however. For
example, a server may be "up" and theoretically capable of handling
requests, but not actually ready yet. Perhaps the router-registrar should
have some contract with its colocated jobs where those jobs can define a
health check script, and the route-registrar will only update the route
registration if the check succeeds.

Another requirement may exist around shutdown behaviour. Jobs may only
want to stop having its routes registered at a certain point in its drain
lifecycle.

*We would like feedback* from anyone maintaining a job or release that
does some sort of route registration to gather requirements that would be
desired of a generic route-registration component.

Thanks,
Amit, CF OSS Release Integration team

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