geoloop.cgi

#!/usr/bin/env perl
############################################################ IDENT(1)
#
# $Title: CGI to convert InfluxDB map data to GeoJSON via JSONP $
# $Copyright: 2018 Devin Teske. All rights reserved. $
# $FrauBSD$
#
############################################################ INCLUDES

use strict;
use warnings;
use CGI;

############################################################ CONFIGURATION

my $duration = "30m";
my $series_geoid_tag = "id_tag";

#
# Database and query to get location data
# NB: This is converted to GeoJSON points
#
my $DBNAME = "mydb";
my $DBHOST = "localhost";
my $DBPORT = 8086;
my $FIELDS = join ", ", map { "last($_)" } qw/latitude longitude/;
my $QUERY = join " ",
    "select $FIELDS from tail where time >= now() - 30m",
    "group by $series_geoid_tag fill(none)";

############################################################ GLOBALS

our $| = 1; # Disable output buffering

my $tag;
my $lat;
my $lng;

my $cgi = new CGI;

my $callback = "data";

############################################################ MAIN

#
# Print HTTP response header
#
print $cgi->header({ type => "application/json" });

#
# Perform database query
#
open CMD, "-|", join " ", "influx",
    qq/-host "$DBHOST" -port "$DBPORT" -database "$DBNAME"/,
    qq/-execute "$QUERY"/ or die "influx: $!";

#
# Print callback and GeoJSON preamble
#
$callback = $cgi->param("callback") || $callback;
print qq/$callback({ "type": "FeatureCollection",
  "features": [/;

#
# Convert latitude/longitude into GeoJSON points
#
my $sep = 0;
while (<CMD>) {
    next if /^(name: tail)?$/;
    $tag = $1 and next if /^tags: $series_geoid_tag=(\d+)$/;
    next if /^(time|--)/;
    next unless /^\d+\s+(-?\d+\.\d+)\s+(-?\d+\.\d+)/
        || /^\d+\s+(-?\d+\.\d+)\s+(-?\d+)/
        || /^\d+\s+(-?\d+)\s+(-?\d+\.\d+)/
        || /^\d+\s+(-?\d+)\s+(-?\d+)/;
    ($lat, $lng) = ($2, $1);
    print "," unless $sep++ == 0;
    print qq/\n    { "type": "Feature", "id": $tag,/;
    print qq/\n      "geometry": {"type": "Point", /;
    print qq/"coordinates": [$lat, $lng]/;
    print qq/}}/;
}

#
# Terminate GeoJSON[P] structure
#
print qq/
  ]
});\n/;

close CMD;
exit 0;

################################################################################
# END
################################################################################