Say when a named log source answered with nothing

An ipmi node named no source at all, so -s dropped every event, and a
log with no entries can never be named by one.

confluent_client/bin/nodeeventlog

@@ -201,10 +201,20 @@ elif wantsources is not None:
     for node in nodes:
         found = set(x.lower() for x in sources_seen.get(node, ()))
         missing = wantsources - found
-        if missing and found:
+        if not missing:
+            continue
+        if found:
             sys.stderr.write('{0}: no such log source: {1}, this node has {2}\n'
                              .format(node, ','.join(sorted(missing)),
                                      ','.join(sorted(sources_seen[node]))))
+        else:
+            # A log that holds no entries names no source, so an empty answer
+            # here is as often a quiet platform as a wrong name.  Either way
+            # saying nothing would look like the log simply had nothing in it.
+            sys.stderr.write(
+                '{0}: no entries from any log source, so nothing could match '
+                '{1}\n'.format(node, ','.join(sorted(missing))))
+        exitcode |= 1
 
 if options.lines and not listmode:
     for node in nodes:

confluent_client/doc/man/nodeeventlog.ronn

@@ -15,6 +15,11 @@ noisier than others.  Reading gathers every log the platform describes as an
 event log, wherever it keeps them, and `-s` narrows the output to the ones
 asked for.  `-s list` names the logs a node offers rather than showing entries.
 
+A source is named by the entries that come from it, so a log that holds no
+entries is not among them, and a node whose logs are all empty names none.  An
+ipmi managed node keeps its events in the one log the spec gives it, which is
+reported as `SEL`.
+
 Clearing is deliberately narrower than reading: it only touches the logs the
 platform's own manager publishes, so a log that only a read reaches is never
 destroyed by one.  A selection cannot be cleared, so `-s` and `clear` are
@@ -39,6 +44,8 @@ refused together.
    only show entries from the named logs, comma delimited and matched without
    regard to case. `-s list` names the logs the node offers instead of showing
    entries. A platform that named a log "list" would be shadowed by that.
+   Asking for a log the node named nothing from is reported on stderr and
+   exits non-zero, rather than looking like an empty log.
 
 * `-h`, `--help`:
   Show help message and exit  

confluent_server/confluent/plugins/hardwaremanagement/ipmi.py

@@ -933,6 +933,10 @@ class IpmiHandler:
         await self.output.put(msg.EventCollection(eventout, name=self.node))
 
     def pyghmi_event_to_confluent(self, event):
+        # An ipmi platform keeps its events in one place and the spec has a
+        # name for it, so say so rather than leaving the source blank and
+        # having a caller asking for a named log get nothing back
+        event.setdefault('log_id', 'SEL')
         event['severity'] = _str_health(event.get('severity', 'unknown'))
         if 'event_data' in event:
             event['event'] = '{0} - {1}'.format(