Added Consul health checks state monitoring. (#1294)

plugins/inputs/consul/README.md

@@ -0,0 +1,46 @@
+# Telegraf Input Plugin: Consul
+
+This plugin will collect statistics about all helath checks registered in the Consul. It uses [Consul API](https://www.consul.io/docs/agent/http/health.html#health_state)
+to query the data. It will not report the [telemetry](https://www.consul.io/docs/agent/telemetry.html) but Consul can report those stats already using StatsD protocol if needed.
+
+## Configuration:
+
+```
+# Gather health check statuses from services registered in Consul
+[[inputs.consul]]
+  ## Most of these values defaults to the one configured on a Consul's agent level.
+  ## Optional Consul server address (default: "")
+  # address = ""
+  ## Optional URI scheme for the Consul server (default: "")
+  # scheme = ""
+  ## Optional ACL token used in every request (default: "")
+  # token = ""
+  ## Optional username used for request HTTP Basic Authentication (default: "")
+  # username = ""
+  ## Optional password used for HTTP Basic Authentication (default: "")
+  # password = ""
+  ## Optional data centre to query the health checks from (default: "")
+  # datacentre = ""
+```
+
+## Measurements:
+
+### Consul:
+Tags:
+- node: on which node check/service is registered on
+- service_name: name of the service (this is the service name not the service ID)
+
+Fields:
+- check_id
+- check_name
+- service_id
+- status
+
+## Example output
+
+```
+$ telegraf --config ./telegraf.conf -input-filter consul -test
+* Plugin: consul, Collection 1
+> consul_health_checks,host=wolfpit,node=consul-server-node check_id="serfHealth",check_name="Serf Health Status",service_id="",status="passing" 1464698464486439902
+> consul_health_checks,host=wolfpit,node=consul-server-node,service_name=www.example.com check_id="service:www-example-com.test01",check_name="Service 'www.example.com' check",service_id="www-example-com.test01",status="critical" 1464698464486519036
+```