tree 5a8138bce6a5aaf4f28c66f7dcd2270083aaf57c
parent 31c7100229796bb7f0d8792d0160c4a66c3049a8
author David Pursehouse <dpursehouse@collab.net> 1510903098 +0900
committer Hugo Arès <hugo.ares@ericsson.com> 1511545879 -0500

Initial implementation of health servlet

The health servlet allows the plugin to be used to return responses
to HAProxy's health check function [1].  For example if the http(s)
backend is configured with something like:

  option httpchk GET /plugins/high-availability/health

then GET calls to the /health URL will return HTTP status 204, thus
indicating that the server is healthy (the default response).

Sending a DELETE request to the same /health URL will set the status
to 'unhealthy', and then any subsequent GET requests will return HTTP
503.

Sending a POST request sets the status back to 'healthy'.

Documentation and tests will be added in follow up changes.

[1] http://cbonte.github.io/haproxy-dconv/1.7/configuration.html#option%20httpchk

Change-Id: Ife2e6176347c5a84f328b9652a2613080572c994