doc: Add information on how to enable the rbd-images dashboard

Fixes: https://tracker.ceph.com/issues/44623
Signed-off-by: Enno Gotthold <egotthold@suse.de>
In the previous commit (1c52ee2b) the added dashboard will stay empty
until it is manually enabled to display information.

(cherry picked from commit 6386095e51a1d58fa0093d37b26df25c524b72bc)

Conflicts:
	doc/cephadm/monitoring.rst
        - Delete (file doesn't exist in nautilus)

diff --git a/doc/mgr/prometheus.rst b/doc/mgr/prometheus.rst
index e01196bb0ced4397356af59d448f5e9f7e2bacf6..49c8b242851230a5d4c7ce3b265a10291d599883 100644 (file)
--- a/doc/mgr/prometheus.rst
+++ b/doc/mgr/prometheus.rst
@@ -31,6 +31,8 @@ configurable with ``ceph config-key set``, with keys
 ``mgr/prometheus/server_addr`` and ``mgr/prometheus/server_port``.
 This port is registered with Prometheus's `registry <https://github.com/prometheus/prometheus/wiki/Default-port-allocations>`_.
 
+.. _prometheus-rbd-io-statistics:
+
 RBD IO statistics
 -----------------
 
@@ -41,6 +43,10 @@ configuration parameter. The parameter is a comma or space separated list
 of ``pool[/namespace]`` entries. If the namespace is not specified the
 statistics are collected for all namespaces in the pool.
 
+Example to enable the images ``image1``, ``image2`` and ``imageN``::
+
+  ceph config set mgr mgr/prometheus/rbd_stats_pools "image1,image2,imageN"
+
 The module makes the list of all available images scanning the specified
 pools and namespaces and refreshes it periodically. The period is
 configurable via the ``mgr/prometheus/rbd_stats_pools_refresh_interval``
@@ -48,6 +54,10 @@ parameter (in sec) and is 300 sec (5 minutes) by default. The module will
 force refresh earlier if it detects statistics from a previously unknown
 RBD image.
 
+Example to turn up the sync interval to 10 minutes::
+
+  ceph config set mgr mgr/prometheus/rbd_stats_pools_refresh_interval 600
+
 Statistic names and labels
 ==========================