convert mackerel api result to terraform resource definition

monitors.pl

#!/usr/bin/env perl

use strict;
use warnings;
use JSON::XS;
use Text::MicroTemplate;
use Data::Dumper;

my $env = $ARGV[0];
my $tmts = {};

$tmts->{connectivity} = build_template(<<'EOH');
? my ($env, $name, $monitor) = @_;
resource "mackerel_monitor" "<?= $name ?>" {
  name = "[<?= $env ?>] <?= $monitor->{name} ?>"
? if (defined $monitor->{memo}) {
  memo = <<-EOT
    <?= $monitor->{memo} ?>
  EOT
? }

? if (defined $monitor->{notificationInterval}) {
  notification_interval = <?= $monitor->{notificationInterval} ?>
? }

  connectivity {
    scopes = [
?       for my $scope (@{$monitor->{scopes}}) {
        "<?= $scope ?>",
?       }
    ]
  }
}
EOH

$tmts->{expression} = build_template(<<'EOH');
? my ($env, $name, $monitor) = @_;
resource "mackerel_monitor" "<?= $name ?>" {
  name = "[<?= $env ?>] <?= $monitor->{name} ?>"
? if (defined $monitor->{memo}) {
  memo = <<-EOT
    <?= $monitor->{memo} ?>
  EOT
? }

? if (defined $monitor->{notificationInterval}) {
  notification_interval = <?= $monitor->{notificationInterval} ?>
? }

  expression {
    expression = "<?= $monitor->{expression} ?>"
    operator   = "<?= $monitor->{operator} ?>"
?   if (defined $monitor->{warning}) {
    warning    = "<?= $monitor->{warning} ?>"
?   }
?   if (defined $monitor->{critical}) {
    critical   = "<?= $monitor->{critical} ?>"
?   }
  }
}
EOH

$tmts->{external} = build_template(<<'EOH');
? my ($env, $name, $monitor) = @_;
resource "mackerel_monitor" "<?= $name ?>" {
  name = "[<?= $env ?>] <?= $monitor->{name} ?>"
? if (defined $monitor->{memo}) {
  memo = <<-EOT
<?= $monitor->{memo} ?>
  EOT
? }

? if (defined $monitor->{notificationInterval}) {
  notification_interval = <?= $monitor->{notificationInterval} ?>
? }

  external {
    method                            = "<?= $monitor->{method} ?>"
    url                               = "<?= $monitor->{url} ?>"
    service                           = "<?= $monitor->{service} ?>"
    response_time_critical            = <?= $monitor->{responseTimeCritical} ?>
    response_time_warning             = <?= $monitor->{responseTimeWarning} ?>
    response_time_duration            = <?= $monitor->{responseTimeDuration} ?>
    max_check_attempts                = <?= $monitor->{maxCheckAttempts} ?>
    certification_expiration_warning  = <?= $monitor->{certificationExpirationWarning} ?>
    certification_expiration_critical = <?= $monitor->{certificationExpirationCritical} ?>

    headers = {
?       for my $header (@{$monitor->{headers}}) {
        <?= $header->{name} ?> = "<?= $header->{value} ?>"
?       }
    }
  }
}
EOH

$tmts->{host} = build_template(<<'EOH');
? my ($env, $name, $monitor) = @_;
resource "mackerel_monitor" "<?= $name ?>" {
  name = "[<?= $env ?>] <?= $monitor->{name} ?>"
? if (defined $monitor->{memo}) {
  memo = <<-EOT
<?= $monitor->{memo} ?>
  EOT
? }

? if (defined $monitor->{notificationInterval}) {
  notification_interval = <?= $monitor->{notificationInterval} ?>
? }

  host_metric {
    metric             = "<?= $monitor->{metric} ?>"
    operator           = "<?= $monitor->{operator} ?>"
?   if (defined $monitor->{warning}) {
    warning            = "<?= $monitor->{warning} ?>"
?   }
?   if (defined $monitor->{critical}) {
    critical           = "<?= $monitor->{critical} ?>"
?   }
    duration           = "<?= $monitor->{duration} ?>"
    max_check_attempts = <?= $monitor->{maxCheckAttempts} ?>

    scopes = [
?       for my $scope (@{$monitor->{scopes}}) {
        "<?= $scope ?>",
?       }
    ]
  }
}
EOH

$tmts->{service} = build_template(<<'EOH');
? my ($env, $name, $monitor) = @_;
resource "mackerel_monitor" "<?= $name ?>" {
  name = "[<?= $env ?>] <?= $monitor->{name} ?>"
? if (defined $monitor->{memo}) {
  memo = <<-EOT
<?= $monitor->{memo} ?>
  EOT
? }

? if (defined $monitor->{notificationInterval}) {
  notification_interval = <?= $monitor->{notificationInterval} ?>
? }

  service_metric {
    service            = "<?= $monitor->{service} ?>"
    metric             = "<?= $monitor->{metric} ?>"
    operator           = "<?= $monitor->{operator} ?>"
    duration           = <?= $monitor->{duration} ?>
?   if (defined $monitor->{warning}) {
    warning            = "<?= $monitor->{warning} ?>"
?   }
?   if (defined $monitor->{critical}) {
    critical           = "<?= $monitor->{critical} ?>"
?   }
    max_check_attempts = <?= $monitor->{maxCheckAttempts} ?>
  }
}
EOH

sub build_template {
    my ($tmpl) = @_;

    return Text::MicroTemplate->new(
        template    => $tmpl,
        escape_func => undef,
    )->build;
}

while (my $line = <STDIN>) {
    my $monitor = decode_json($line);
    my $tmt     = $tmts->{ $monitor->{type} };

    if ($tmt) {
        my $name = $monitor->{name};
        $name =~ s/[\s\.]+/-/g;
        $name = lc($name);
        $name = sprintf("%s-%s", $monitor->{type}, $name);

        print $tmt->($env, $name, $monitor);
        print "\n";
    }
    else {
        warn "unknown type: " . $monitor->{type};
    }
}

=disclaimer

This script not covers all attributes of terraform resource "mackerel_monitor"
Please check terraform plan before terraform apply.

=usage

    $ curl -s -H "X-Api-Key: $MACKEREL_APIKEY" 'https://api.mackerelio.com/api/v0/monitors' | jq '.monitors[]' | perl monitors.pl