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March 6, 2021 22:20
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Tail a logfile with Mojolicious (for example /var/log/messages)
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| #!/usr/bin/env perl | |
| use Mojolicious::Lite; | |
| package Model::FileWatch { | |
| use Mojo::Base 'Mojo::EventEmitter'; | |
| use Mojo::Promise; | |
| use IO::File; | |
| has 'file'; | |
| sub watch { | |
| my $self = shift; | |
| my $p = Mojo::Promise->new; | |
| my $fh = IO::File->new; | |
| unless ($fh->open($self->file, 'r')) { | |
| return $p->reject("watching @{[$self->file]} failed: $!"); | |
| } | |
| $fh->seek(0, 2); | |
| my $id = $p->ioloop->recurring( | |
| 0.25 => sub { | |
| $fh->seek(0, 1); | |
| if (my $line = $fh->getline) { | |
| $self->emit(oneline => $line); | |
| } | |
| } | |
| ); | |
| $self->once(finish => sub { $p->ioloop->remove($id) }); | |
| $p; | |
| } | |
| } | |
| websocket '/tail' => sub { | |
| my $c = shift; | |
| my $m = Model::FileWatch->new(file => '/var/log/messages'); | |
| $c->inactivity_timeout(300); | |
| $m->on( | |
| oneline => sub { | |
| my ($tail, $line) = @_; | |
| $c->send($line); | |
| } | |
| ); | |
| $c->on(finish => sub { $m->emit('finish')->unsubscribe('oneline') }); | |
| $m->watch->catch(sub { $c->send(@_) })->wait; | |
| }; | |
| get '/' => 'index'; | |
| app->start; | |
| __DATA__ | |
| @@ index.html.ep | |
| <!DOCTYPE html> | |
| <html> | |
| <head><title>Tail</title></head> | |
| <body> | |
| <script> | |
| var ws = new WebSocket('<%= url_for('tail')->to_abs %>'); | |
| // Incoming messages | |
| ws.onmessage = function (event) { | |
| document.body.innerHTML += event.data + '<br/>'; | |
| window.scrollTo(0, document.body.scrollHeight); | |
| }; | |
| // Ping from client side to keep WS connection alive | |
| window.setInterval(function () { ws.send('') }, 10000); | |
| </script> | |
| </body> | |
| </html> | |
| __END__ |
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