Improve netdisco-sshcollector CLI experience (#460)

* Improve netdisco-sshcollector CLI experience

 * add -d <device>
 * add -O debug option to toggle Net::OpenSSH::debug
 * add -w MCE::Loop max_workers
 * updated POD for all of the above

* Fix -Q documentation

 * Specifying -Q multiple times has no effect, removed part talking about that.

* Emit Net::OpenSSH connection failures as warnings

bin/netdisco-sshcollector

@@ -53,10 +53,13 @@ use Pod::Usage 'pod2usage';
 use Getopt::Long;
 Getopt::Long::Configure ("bundling");
 
-my ($debug, $sqltrace) = (undef, 0);
+my ($debug, $sqltrace, $device, $opensshdebug, $workers) = (undef, 0, undef, undef, "auto");
 my $result = GetOptions(
-  'debug|D'    => \$debug,
+  'debug|D' => \$debug,
-  'sqltrace|Q+'  => \$sqltrace,
+  'sqltrace|Q' => \$sqltrace,
+  'device|d=s' => \$device,
+  'opensshdebug|O' => \$opensshdebug,
+  'workers|w=i' => \$workers,
 ) or pod2usage(
   -msg => 'error: bad options',
   -verbose => 0,
@@ -71,10 +74,11 @@ $ENV{DBIC_TRACE} ||= $sqltrace;
 # reconfigure logging to force console output
 Dancer::Logger->init('console', $CONFIG);
 
-#this may be helpful with SSH issues:
+if ($opensshdebug){
-#$Net::OpenSSH::debug = ~0;
+    $Net::OpenSSH::debug = ~0;
+}
 
-MCE::Loop::init { chunk_size => 1 };
+MCE::Loop::init { chunk_size => 1, max_workers => $workers };
 my %stats;
 $stats{entry} = 0;
 
@@ -83,6 +87,11 @@ exit main();
 sub main {
     my @input = @{ setting('sshcollector') };
 
+    if ($device){
+        @input = grep{ ($_->{hostname} && $_->{hostname} eq $device) 
+            || ($_->{ip} && $_->{ip} eq $device) } @input; 
+    }
+
     #one-line Fisher-Yates from https://www.perlmonks.org/index.pl?node=Array%20One-Liners
     my ($i,$j) = (0);
     @input[-$i,$j] = @input[$j,-$i] while $j = rand(@input - $i), ++$i < @input;
@@ -108,7 +117,12 @@ sub main {
                 ],
             );
 
-            MCE->gather( process($hostlabel, $ssh, $host) );
+           
+            if ($ssh->error){ 
+                warning "WARNING: Couldn't connect to <$hostlabel> - " . $ssh->error;
+            }else{
+                MCE->gather( process($hostlabel, $ssh, $host) );
+            }
         }
     } \@input;
 
@@ -173,7 +187,10 @@ full SNMP support
  ~/bin/localenv cpanm --notest Net::OpenSSH Expect
  
  # run manually, or add to cron:
- ~/bin/netdisco-sshcollector [-DQ]
+ ~/bin/netdisco-sshcollector [-DQO] [-w <max_workers>] 
+
+ # limit run to a single device defined in the config
+ ~/bin/netdisco-sshcollector [-DQO] [-w <max_workers>] -d <device> 
 
 =head1 DESCRIPTION
 
@@ -271,10 +288,7 @@ don't support command execution via ssh:
 The returned IP and MAC addresses should be in a format that the respective
 B<inetaddr> and B<macaddr> datatypes in PostgreSQL can handle.   
 
-=head1 DEBUG LEVELS
+=head1 COMMAND LINE OPTIONS
-
-The flags "C<-DQ>" can be specified, multiple times, and enable the following
-items in order:
 
 =over 4
 
@@ -284,7 +298,21 @@ Netdisco debug log level
 
 =item C<-Q>
 
-L<DBIx::Class> trace enabled
+L<DBIx::Class> trace enabled.
+
+=item C<-O>
+
+L<Net::OpenSSH> trace enabled
+
+=item C<-w>
+
+Set maximum parallel workers for L<MCE::Loop>. The default is B<auto>. 
+
+=item C<-d device>
+
+Only run for a single device. Takes an IP or hostname, must exactly match the value 
+in the config file. 
+
 
 =back