documentation: prometheus: Improvements

Signed-off-by: Julien Pivotto <roidelapluie@inuits.eu>

docs/prometheus.md

@@ -24,15 +24,16 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 Mgmt comes with a built-in prometheus support. It is disabled by default, and
 can be enabled with the `--prometheus` command line switch.
 
-By default, the prometheus instance will listen on [`127.0.0.1:9233`][pd]. You can
-change this setting by using the `--prometheus-listen` cli option:
+By default, the prometheus instance will listen on [`127.0.0.1:9233`][pd]. You
+can change this setting by using the `--prometheus-listen` cli option:
 
 To have mgmt prometheus bind interface on 0.0.0.0:45001, use:
 `./mgmt r --prometheus --prometheus-listen :45001`
 
 ## Metrics
 
-Mgmt exposes two kinds of resources: _go_ metrics and _mgmt_ metrics.
+Mgmt exposes three kinds of resources: _go_ metrics, _etcd_ metrics and _mgmt_
+metrics.
 
 ### go metrics
 
@@ -48,13 +49,19 @@ mgmt exposes etcd metrics. Read more in the [upstream documentation][etcdm]
 Here is a list of the metrics we provide:
 
 - `mgmt_resources_total`: The number of resources that mgmt is managing
-- `mgmt_checkapply_total`: The number of checkapplies that mgmt has run.
+- `mgmt_checkapply_total`: The number of CheckApply's that mgmt has run
 - `mgmt_failures_total`: The number of resources that have failed
 - `mgmt_failures_current`: The number of resources that have failed
 
 For each metric, you will get some extra labels:
 
-- `resource_type`: The type of mgmt resource
+- `kind`: The kind of mgmt resource
+
+For `mgmt_checkapply_total`, those extra labels are set:
+
+- `eventful`: "true" or "false", if the CheckApply triggered some changes
+- `errorful`: "true" or "false", if the CheckApply reported an error
+- `apply`: "true" or "false", if the CheckApply ran in apply or noop mode
 
 ## Alerting