Feature: Simple health checking

[birkland]

Create a an API-X component that performs basic health checks (e.g periodic HEAD requests) and removes unhealthy services from an LDP service instance registry.

The intent of this is to provide simple-to-use functionality out of the box for those who unable to leverage an existing infrastructure that offers health checking and registry maintenance, such as consul or zookeeper.

It should straightforward to use this or not use it.

This may be demonstrated in a Docker demo this by having the user run a local service (i.e. on their own machine) that self-registers, and is subsequently killed by the user via ctrl-c

So a demo might look like:

• user starts API-X
• runs local service on command line which self-registers itself as an extension
• verify that it's working via API-X
• Shut down local service
• Should get 503 error if there are no available services to satisfy the request

[ajs6f]

Interesting that that's a 503. If you have time can you point me at the spec that details that?

[birkland]

@ajs6f There's nothing in the API-X design doc that spells that out, but this would be a good opportunity to do so. 503 just seemed logical because:

• There's an extension definition (still) in place (from when the extension self-registered) which spells out the intent that API-X exposes the given service at a particular location, but
• There are no service instances available to handle the request