scaler.php

<?php

use Aws\Ec2\Ec2Client;
use Aws\ElasticBeanstalk\ElasticBeanstalkClient;
use Aws\ElasticBeanstalk\Exception\ElasticBeanstalkException;
use Aws\Rds\Exception\RdsException;
use Aws\Rds\RdsClient;

require __DIR__.'/vendor/autoload.php';

if (2 !== $argc || !is_numeric($argv[1])) {
    die("Usage: {$argv[0]} [office hours, 0 or 1]\n");
}

function restructureTags($tags)
{
    return array_column($tags, 'Value', 'Key');
}

function getDesiredEbInstanceType(string $environment, bool $isOfficeHours, string $officeHoursInstanceType): string
{
    if ($isOfficeHours) {
        return $officeHoursInstanceType;
    }

    if ('Production' === $environment) {
        return 't2.small';
    }

    return 't2.micro';
}

function handleRdsException($rdsInstance, RdsException $exception)
{
    $response = new SimpleXMLElement($exception->getResponse()->getBody());
    echo "Failed switching {$rdsInstance['DBInstanceIdentifier']} to type {$rdsInstance['DesiredInstanceType']} due to: {$response->Error->Message}\n";
}

$isOfficeHours = (bool) intval($argv[1]);

$ec2Client = new Ec2Client($clientConfig = [
    'region' => 'eu-central-1',
    'version' => 'latest',
]);

$ebClient = new ElasticBeanstalkClient($clientConfig);
$rdsClient = new RdsClient($clientConfig);

$instances = array_column(
    array_column(
        $ec2Client->describeInstances()->get('Reservations'),
        'Instances'
    ),
    0
);

$instances = array_map(function ($instance) {
    if (isset($instance['Tags'])) {
        $instance['Tags'] = restructureTags($instance['Tags']);

        if (!isset($instance['Tags']['OfficeHoursInstType'])) {
            return $instance;
        }

        $instance['OfficeHoursInstType'] = $instance['Tags']['OfficeHoursInstType'];
    }

    return $instance;
}, $instances);

$taggedInstances = array_filter($instances, function ($instance) {
    return !empty($instance['OfficeHoursInstType']) && 'terminated' !== $instance['State']['Name'];
});

$taggedInstances = array_map(function ($instance) use ($isOfficeHours) {
    $instance['DesiredInstanceType'] = $isOfficeHours
        ? $instance['OfficeHoursInstType']
        : (($instance['EbsOptimized'] ? 't3.' : 't2.').(stristr($instance['Tags']['Name'], 'freebsd') ? 'small' : 'micro'));

    return $instance;
}, $taggedInstances);

foreach ($taggedInstances as $instance) {
    if ($instance['InstanceType'] === $instance['DesiredInstanceType']) {
        if ('stopped' === $instance['State']['Name']) {
            echo "Starting instance {$instance['InstanceId']} (currently in state {$instance['State']['Name']})\n";
            $result = $ec2Client->startInstances([
                'InstanceIds' => [$instance['InstanceId']],
            ]);
        }
    } else {
        if ('running' === $instance['State']['Name']) {
            $environmentIdentifier = [];
            if (isset($instance['Tags']['elasticbeanstalk:environment-id'])) {
                $environments = $ebClient->describeEnvironments(['EnvironmentIds' => [$instance['Tags']['elasticbeanstalk:environment-id']]])->get('Environments');
                if (!is_array($environments) || !count($environments)) {
                    continue;
                }

                $environmentIdentifier = array_intersect_key($environments[0], ['ApplicationName' => '', 'EnvironmentName' => '']);
                $configuration = $ebClient->describeConfigurationSettings($environmentIdentifier)->get('ConfigurationSettings')[0];
                if (!is_array($configuration)) {
                    continue;
                }

                $configuredInstanceType = array_values(array_filter($configuration['OptionSettings'], function ($setting) {
                    return 'aws:ec2:instances' === $setting['Namespace'] && 'InstanceTypes' === $setting['OptionName'];
                }))[0]['Value'];

                if (!strlen($configuredInstanceType)) {
                    continue;
                }

                $desiredInstanceType = getDesiredEbInstanceType(
                    $environmentIdentifier['EnvironmentName'],
                    $isOfficeHours,
                    $officeHoursInstanceType = implode(',', explode(' ', $instance['OfficeHoursInstType']))
                );

                echo "Updating instance type for app/env {$environmentIdentifier['ApplicationName']} / {$environmentIdentifier['EnvironmentName']} to {$desiredInstanceType}\n";

                $optionSettings = [
                    'OptionSettings' => [
                        [
                            'Namespace' => 'aws:ec2:instances',
                            'OptionName' => 'InstanceTypes',
                            'Value' => $desiredInstanceType,
                        ],
                    ],
                ];

                try {
                    $ebClient->updateEnvironment(
                        array_merge(
                            $environmentIdentifier,
                            $optionSettings
                        )
                    );
                } catch (ElasticBeanstalkException $exception) {
                    echo $exception->getAwsErrorMessage();
                }
            } else {
                echo "Stopping instance {$instance['InstanceId']} ({$instance['Tags']['Name']})\n";
                $result = $ec2Client->stopInstances([
                    'InstanceIds' => [$instance['InstanceId']],
                ]);
            }
        } elseif ('stopped' === $instance['State']['Name']) {
            echo "Changing instance {$instance['InstanceId']} to type {$instance['DesiredInstanceType']} and starting\n";

            $result = $ec2Client->ModifyInstanceAttribute([
                'InstanceId' => $instance['InstanceId'],
                'InstanceType' => [
                    'Value' => $instance['DesiredInstanceType'],
                ],
            ]);

            $result = $ec2Client->startInstances([
                'InstanceIds' => [$instance['InstanceId']],
            ]);
        } else {
            echo "Awaiting state change for instance {$instance['InstanceId']}, currently in state {$instance['State']['Name']}\n";
        }
    }
}

$rdsInstances = $rdsClient->describeDBInstances()->get('DBInstances');

if (file_exists($cacheFile = __DIR__.'/.instance-type-tags.serialized') && filectime($cacheFile) > time() - 600) {
    $instanceTypeTags = unserialize(file_get_contents($cacheFile));
} else {
    $instanceTypeTags = [];
    foreach ($rdsInstances as $rdsInstance) {
        $tags = restructureTags($rdsClient->listTagsForResource(['ResourceName' => $rdsInstance['DBInstanceArn']])->get('TagList'));
        if (empty($tags['OfficeHoursInstType'])) {
            continue;
        }
        $instanceTypeTags[$rdsInstance['DBInstanceIdentifier']] = $tags['OfficeHoursInstType'];
    }
    @unlink($cacheFile);
    file_put_contents($cacheFile, serialize($instanceTypeTags));
}

foreach ($rdsInstances as $rdsInstance) {
    if (!isset($instanceTypeTags[$rdsInstance['DBInstanceIdentifier']])) {
        continue;
    }
    $rdsInstance['DesiredInstanceType'] = $isOfficeHours ? $instanceTypeTags[$rdsInstance['DBInstanceIdentifier']] : 'db.t2.micro';
    if ($rdsInstance['DesiredInstanceType'] === $rdsInstance['DBInstanceClass']) {
        continue;
    }

    if ('modifying' === $rdsInstance['DBInstanceStatus']) {
        echo "Changes are currently being applied to {$rdsInstance['DBInstanceIdentifier']}\n";
    } elseif ('available' !== $rdsInstance['DBInstanceStatus']) {
        echo "Skipping change to {$rdsInstance['DBInstanceIdentifier']} due to unavailability\n";
    } else {
        try {
            $rdsClient->modifyDBInstance([
                'DBInstanceIdentifier' => $rdsInstance['DBInstanceIdentifier'],
                'ApplyImmediately' => true,
                'DBInstanceClass' => $rdsInstance['DesiredInstanceType'],
            ]);

            echo "Switching {$rdsInstance['DBInstanceIdentifier']} to type {$rdsInstance['DesiredInstanceType']}\n";
        } catch (RdsException $exception) {
            if (
                !$isOfficeHours &&
                'InvalidParameterCombination' === $exception->getAwsErrorCode()
            ) {
                try {
                    $rdsClient->modifyDBInstance([
                        'DBInstanceIdentifier' => $rdsInstance['DBInstanceIdentifier'],
                        'ApplyImmediately' => true,
                        'DBInstanceClass' => 'db.t2.small',
                    ]);
                } catch (RdsException $exception) {
                    handleRdsException($rdsInstance, $exception);
                }
            } else {
                handleRdsException($rdsInstance, $exception);
            }
        }
    }
}