mgr: add doc to describe relationship to prometheus

The healthcheck for slow_ops is used by the mgr/prometheus
module so it's important the alert generated matches the
format expected in mgr/prometheus.

Signed-off-by: Paul Cuzner <pcuzner@redhat.com>

diff --git a/src/mgr/DaemonHealthMetricCollector.cc b/src/mgr/DaemonHealthMetricCollector.cc
index 4b51100ee2e7eacd132f99290b3b880daccea3fd..53c0b78a6904ccce3804af9b24c04fedccac92d5 100644 (file)
--- a/src/mgr/DaemonHealthMetricCollector.cc
+++ b/src/mgr/DaemonHealthMetricCollector.cc
@@ -30,6 +30,8 @@ class SlowOps final : public DaemonHealthMetricCollector {
     if (daemons.empty()) {
       return;
     }
+    // Note this message format is used in mgr/prometheus, so any change in format
+    // requires a corresponding change in the mgr/prometheus module.
     ostringstream ss;
     if (daemons.size() > 1) {
       if (daemons.size() > 10) {