dashboard: configuration setting browser
Ceph stores the configuration for all its daemons according to a schema defined within the C++ code in src/common/options.cc. This can currently be viewed on live systems by using a command like "ceph daemon mon.a config help".
That schema information is also available inside ceph-mgr, although it isn't currently exposed to the python modules. Modules can currently call MgrModule.get("config") to get the current values (the equivalent of "config show" command line), which is satisfied by the C++ code here: https://github.com/ceph/ceph/blob/master/src/mgr/ActivePyModules.cc#L190
If the C++ side is extended to enable python modules to retrieve the config schema, then the dashboard can then be extended with a page that shows all the possible configuration values and their documentation strings. The config option schema includes a "services" field that shows which options apply to which type of service, so the configuration page in the dashboard should be filterable by service.
This view will be a useful online documentation resource for engineers and administrators. It doesn't need to show any current values -- the values available in ceph-mgr are currently only for the mgr daemon itself (not the rest of the cluster), so it would be misleading to display them.