tail_logfile: read from journalctl, not pause.log

This means we can stop writing pause.log!

Also, this switches from "last n bytes" to "last n lines" and so adjusts
the options a bit.

Author: rjbs

lib/pause_2017/PAUSE/Web/Controller/User.pm

@@ -300,17 +300,18 @@ sub tail_logfile {
   my $pause = $c->stash(".pause");
   my $req = $c->req;
 
-  my $tail = $req->param("pause99_tail_logfile_1") || 5000;
-  my $file = $PAUSE::Config->{PAUSE_LOG};
+  my $lines = $req->param("pause99_tail_logfile_1") || 1000;
 
-  open my $fh, "<", $file or die "Could not open $file: $!";
-  seek $fh, -$tail, 2;
-  local($/);
-  $/ = "\n";
-  <$fh>;
-  $/ = undef;
+  my @valid_options = qw(500 1000 10000 20000);
+  unless (grep {; $lines eq $_ } @valid_options) {
+    $lines = 500;
+  }
+
+  my $logs = readpipe("/usr/bin/journalctl --lines $lines --identifier paused");
+
+  $logs = qq{Error reading PAUSE daemon logs!\n} if $? != 0;
 
-  $pause->{tail} = <$fh>;
+  $pause->{tail} = $logs;
 }
 
 sub change_passwd {

lib/pause_2017/templates/user/tail_logfile.html.ep

@@ -2,8 +2,8 @@
 % my $pause = stash(".pause") || {};
 
 <div id="logs">
-<%= select_field pause99_tail_logfile_1 => [qw/2000 5000 10000 20000 40000/]; =%>
-<input type="submit" name="pause99_tail_logfile_sub" value="Tail characters">
+<%= select_field pause99_tail_logfile_1 => [qw/500 1000 10000 20000/]; =%>
+<input type="submit" name="pause99_tail_logfile_sub" value="Tail lines">
 <input class="search" placeholder="Filter">
 <table class="table compact">
   <tbody class="list">