Short term: Config files.

Medium term: Consul?

discovery via HTTP and DNS
config store
some circuit breaking ability as items are removed from discovery based on health checks

Long term: PaaS platform?

Flynn - more ambitious, but explicitly stated to be not production ready.
Deis - claimed to be production ready, but the list of users is pretty thin at the moment, and some really glaring missing features (e.g. routing between services via methods other than HTTP).
These are not mature enough platforms yet, but they show a lot of promise for being able to tame some of the complexity as we move towards having many services.
Docker-based, Heroku-like deployment style
Can run on all the major cloud providers or on bare metal.

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