💉 Add health check for hosting containerized tiled instances

[Kezzsim]

Kubernetes and other container orchestration platforms require pods that expose themselves as services to prove that they are alive and ready to handle HTTP responses, while this response can be baked into deployment yml, it's considered best practice to actually have the service return something indicating that it is healthy.

This implements the spec defined in the Kubernetes Readyness Probe section.

This resolves part of issue #648

[dylanmcreynolds]

This is great.

Is there any configuration you have to do in k8s to invoke this, or is it automagic?

There is a docker-compose.yml in the root of the tiled repo. Perhaps this is a future PR, but it might be nice to add the health check to it, now that it's possible. Here's an example

[Kezzsim]

Good idea!
Yeah we rushed this PR through on a call so we could deploy to our Rancher instance, the /healthz endpoint check is standard in spec and seems to work with any Kubernetes instance out of the box.