stream

I want to stream my logs on my home RPi3b to a Slack channel for my vacation side project. With some searches I found an article including a simple shell script to implement this function: "Stream Any Log File to Slack Using curl".

However it's a little tricky as the script replaces " to ' as escaping mechanism. I would prefer to use more formal way to implement this, also, I haven't written Perl for a while, so I have decided to implement this function in Perl:

	#!/usr/bin/perl
	use v5.14;
	use strict;
	use warnings;
	use IO::File;
	use JSON::PP;
	use WWW::Mechanize;
	sub main() {
	my $webhook_url = $ARGV[0] or die 'no webhook_url';
	my $filename = $ARGV[1] or die 'no filename';
	my $filter = $ARGV[2] // '';
	my $fh = IO::File->new("tail -F -n0 ${filename} |");
	my $ua = WWW::Mechanize->new;
	while (my $line = <$fh>) {
	next unless $line =~ $filter;
	my $payload = {text => $line, type => 'plain_text'};
	$ua->post(
	$webhook_url,
	'Content-Type' => 'application/json',
	Content => encode_json($payload),
	);
	}
	$fh->close;
	}
	&main;
	__END__

view raw tailslack.pl hosted with by GitHub

In this script there are some notes:

• Choosing tail -F instead of File::Tail is because File::Tail is quite old and no inotify implementation. On the other side, tail performs well in this section.
• Choosing JSON::PP (pure perl version) is because it's built-in in Perl 5.14+, and that's also why I have added use v5.14 requirement in the beginning.
• Choosing WWW::Mechanize for API calling is because there is no built-in module able to handle HTTPS connections, therefore I have decided to install a familiar one (for me).

btw, // operator has been introduced in Perl 5.10, and I didn't think it last there for such a long time...