A perl daemon which sends structured logs from the Journal to a Gelf HTTP endpoint (made for Graylog)
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#!/usr/bin/perl
use warnings;
use strict;
use JSON;
use LWP::UserAgent;
use Encode qw(encode);
use Data::Dumper;
use Compress::Zlib;
use Getopt::Long;
use Config::Any;
my $config = '/etc/systemd/journal-gelf.yml';
my $conf = {};
if (-e $config) {
print "Reading config file $config\n";
$conf = Config::Any->load_files( { files => [ $config ], flatten_to_hash => 1, use_ext => 1 } )->{$config};
}
GetOptions (
'state=s' => \$conf->{state},
'compress!' => \$conf->{compress},
'url=s' => \$conf->{url},
'username=s' => \$conf->{username},
'password=s' => \$conf->{password}
);
$conf->{state} //= '/var/lib/systemd-journal-gelf/state';
$conf->{compress} //= 1;
if (
not $conf->{url} or
($conf->{username} and not $conf->{password}) or
(not $conf->{username} and $conf->{password})
){
help();
die;
}
print "Starting the Systemd Journal GELF uploader daemon\n";
my $ua = LWP::UserAgent->new(
# env_proxy => 1,
keep_alive => 1
);
$ua->default_header( 'Content-Type' => 'application/json' );
if ( $conf->{compress} ){
$ua->default_header( 'Accept-Encoding' => HTTP::Message::decodable );
$ua->default_header( 'Content-Encoding' => 'gzip' );
}
# Check if the state file exists and contains a valid cursor
my $cursor_arg = '';
open CURSOR, "+<", $conf->{state};
if (-e $conf->{state}){
my $cursor = <CURSOR>;
close CURSOR;
if ($cursor and $cursor =~ m/^s=[a-z\d]+;i=[a-z\d]+;b=[a-z\d]+;m=[a-z\d]+;t=[a-z\d]+;x=[a-z\d]+$/){
print "Valid cursor found in " . $conf->{state} . ", will start back from here\n";
$cursor_arg = " --after-cursor='" . $cursor . "'";
} else {
print $conf->{state} . " contains an invalid cursor, so we're wiping it\n";
unlink $conf->{state};
}
}
open JOURNAL, "journalctl -f -o json$cursor_arg |";
while (my $entry = <JOURNAL>){
my $msg = from_json($entry);
my $gelf = {
version => 1.1,
short_message => $msg->{MESSAGE},
host => $msg->{_HOSTNAME},
timestamp => int ($msg->{__REALTIME_TIMESTAMP} / (1000 * 1000)),
level => $msg->{PRIORITY}
};
foreach (grep !/^MESSAGE|_HOSTNAME|__REALTIME_TIMESTAMP|PRIORITY$/, keys %$msg){
my $key = lc (($_ =~ m/^_/) ? $_ : '_' . $_);
$gelf->{$key} = $msg->{$_};
}
my $retry = 0;
my $resp;
do {
if ($retry > 0){
print "Sending message to " . $conf->{url} . " failed : got code " .
$resp->code . " (" . $resp->message . "). Tring again in $retry seconds\n";
sleep $retry;
}
$resp = $ua->post($conf->{url}, Content => Compress::Zlib::memGzip(encode('utf-8', to_json($gelf))));
$retry = ($retry > 0) ? $retry * 2 : 1;
} while ($resp->code != 202 and $retry < 600);
if ($resp->code == 202){
open CURSOR, ">", $conf->{state};
print CURSOR $msg->{__CURSOR};
close CURSOR
} else {
die "Error sending data to GELF server\n";
}
}
sub help {
print <<"_EOF"
Usage: $0 --url=<URL> [--compress|--no-compress] [--user=production --password=secr3t] [--state=/path/to/file]
* --url is the http or https URL where you will push your gelf formated logs. This is mandatory
* --compress or --no-compress : will turn on or off gzip compression of logs. Default is on, but can be usefull to disable for debugging
* --username and --password may be used if URL is protected with a basic auth mecanism. Either both or none must be provided
* --state can be used to specify where to record the last correctly sent message, so we can start from here when
systemd-journal-gelf is restarted or if there's a network problem. Default value is /var/lib/systemd-journal-gelf/state
_EOF
}