management: Expose current mount stats in API and UI

This adds the configured mounts, if there are any, to the API JSON
response for the `/api/nodes` and `/api/node/<node>` endpoints and to
the overview and node-detail UI pages. Time series data is not collected
for these metrics - that should be scraped from the Prometheus endpoint
instead.

Author: the-mikedavis

deps/rabbitmq_management/priv/www/js/global.js

@@ -141,7 +141,8 @@ var ALL_COLUMNS =
      {'Statistics': [['file_descriptors',   'File descriptors',   true],
                      ['erlang_processes',   'Erlang processes',   true],
                      ['memory',             'Memory',             true],
-                     ['disk_space',         'Disk space',         true]],
+                     ['disk_space',         'Disk space',         true],
+                     ['mount_space',        'Other disks',        true]],
       'General': [['uptime',    'Uptime',       true],
                   ['cores',     'Cores',        true],
                   ['info',      'Info',         true],

deps/rabbitmq_management/priv/www/js/tmpl/node.ejs

@@ -131,6 +131,22 @@
 <% } %>
       </td>
     </tr>
+<%
+   for (var i = 0; i < node.mount_stats.length; i++) {
+     var mount = node.mount_stats[i];
+%>
+    <tr>
+      <th>
+        <%= fmt_string(mount.name) %> disk space
+      </th>
+      <td>
+<%= node_stat_bar('available', 'limit', 'low watermark', mount, fmt_bytes_axis,
+                  mount.available < mount.limit ? 'red' : 'green',
+                  mount.available < mount.limit ? 'disk_free-alarm' : null,
+                  true) %>
+      </td>
+    </tr>
+<% } %>
   </table>
 </div>
 </div>

deps/rabbitmq_management/priv/www/js/tmpl/overview.ejs

@@ -93,6 +93,24 @@
   <% if (show_column('overview', 'disk_space')) { %>
     <th>Disk space</th>
   <% } %>
+  <% if (show_column('overview', 'mount_space')) { %>
+    <%
+      var other_disk_names = [];
+      var unique_disk_names = {};
+      for (var i = 0; i < nodes.length; i++) {
+        for (var j = 0; j < nodes[i].mount_stats.length; j++) {
+          var name = nodes[i].mount_stats[j].name;
+          if (!Object.hasOwnProperty(unique_disk_names, name)) {
+            unique_disk_names[name] = true;
+            other_disk_names.push(name);
+          }
+        }
+      }
+    %>
+    <% for (var i = 0; i < other_disk_names.length; i++) { %>
+      <th><%= fmt_string(other_disk_names[i]) %> disk space</th>
+    <% } %>
+  <% } %>
   <% if (show_column('overview', 'uptime')) { %>
     <th>Uptime</th>
   <% } %>
@@ -180,6 +198,20 @@
     <% } %>
      </td>
   <% } %>
+  <% if (show_column('overview', 'mount_space')) { %>
+     <% for (var i = 0; i < other_disk_names.length; i++) {
+          var mount = node.mount_stats.find((m) => m.name == other_disk_names[i]);
+     %>
+       <td>
+         <% if (mount) { %>
+           <%= node_stat_bar('available', 'limit', 'low watermark',
+                             mount, fmt_bytes_axis,
+                             node.disk_free_alarm ? 'red' : 'green',
+                             node.disk_free_alarm ? 'disk_free-alarm' : null, true) %>
+         <% } %>
+       </td>
+     <% } %>
+  <% } %>
   <% if (show_column('overview', 'uptime')) { %>
      <td><span><%= fmt_uptime(node.uptime) %></span></td>
   <% } %>

deps/rabbitmq_management/src/rabbit_mgmt_db.erl

@@ -661,7 +661,8 @@ node_stats(Ranges, Objs, Interval) ->
      StatsD = [{cluster_links, NodeNodeStats}],
      MgmtStats = maps:get(mgmt_stats, NData),
      Details = augment_details(Obj, []), % augmentation needs to be node local
-     combine(Props, Obj) ++ Details ++ Stats ++ StatsD ++ MgmtStats
+     MountStats = [{mount_stats, maps:get(mount_stats, NData, [])}],
+     combine(Props, Obj) ++ Details ++ Stats ++ StatsD ++ MgmtStats ++ MountStats
      end || Obj <- Objs].
 
 combine(New, Old) ->

deps/rabbitmq_management_agent/src/rabbit_mgmt_data.erl

@@ -108,14 +108,15 @@ vhost_data(Ranges, Id) ->
 
 node_data(Ranges, Id) ->
     maps:from_list(
-      [{mgmt_stats, mgmt_queue_length_stats(Id)}] ++
-      [{node_node_metrics, node_node_metrics()}] ++
-      node_raw_detail_stats_data(Ranges, Id) ++
-      [raw_message_data(node_coarse_stats,
+      [{mgmt_stats, mgmt_queue_length_stats(Id)},
+       {node_node_metrics, node_node_metrics()},
+       {node_stats, lookup_element(node_stats, Id)},
+       {mount_stats, [maps:to_list(M) || M <- rabbit_disk_monitor:get_mount_free()]},
+       raw_message_data(node_coarse_stats,
                         pick_range(coarse_node_stats, Ranges), Id),
        raw_message_data(node_persister_stats,
-                        pick_range(coarse_node_stats, Ranges), Id),
-       {node_stats, lookup_element(node_stats, Id)}] ++
+                        pick_range(coarse_node_stats, Ranges), Id)] ++
+      node_raw_detail_stats_data(Ranges, Id) ++
       node_connection_churn_rates_data(Ranges, Id)).
 
 overview_data(_Pid, User, Ranges, VHosts) ->