Watch handlers should get called on rpc error

[jrmithdobbs]

When an rpc error (eg, 500 because of failure/resulting master election) occurs watches should be called in some indicative way so that action can be taken if necessary.

Things like this:

2015/07/11 03:13:33 consul.watch: Watch (type: service) errored: Unexpected response code: 500 (rpc error: unexpected EOF), retry in 5s

In the middle of consul watch <stuff> output

Also when specifying unknown datacenters:

2015/07/11 18:17:06 [ERR] http: Request /v1/health/service/something?dc=unknowndc01, error: No path to datacenter

Watches in the config/initiated from client should have a chance to fire to handle these or maybe specify a separate error handler.

[ryanuber]

Thanks for the suggestion. Makes sense to me, maybe we can export an environment variable to indicate why the watch was fired. Marking as an enhancement.

[jrmithdobbs]

Even just passing a json object detailing the error instead of the normal response would be fine in my eyes.