bootstrap

#!/opt/bin/php -c/opt/php.ini
<?php

error_reporting(E_ALL | E_STRICT);

$AWS_LAMBDA_RUNTIME_API = getenv('AWS_LAMBDA_RUNTIME_API');

/* https://gist.github.com/henriquemoody/6580488 */
$http_codes = [100=>'Continue',101=>'Switching Protocols',102=>'Processing',200=>'OK',201=>'Created',202=>'Accepted',203=>'Non-Authoritative Information',204=>'No Content',205=>'Reset Content',206=>'Partial Content',207=>'Multi-Status',208=>'Already Reported',226=>'IM Used',300=>'Multiple Choices',301=>'Moved Permanently',302=>'Found',303=>'See Other',304=>'Not Modified',305=>'Use Proxy',306=>'Switch Proxy',307=>'Temporary Redirect',308=>'Permanent Redirect',400=>'Bad Request',401=>'Unauthorized',402=>'Payment Required',403=>'Forbidden',404=>'Not Found',405=>'Method Not Allowed',406=>'Not Acceptable',407=>'Proxy Authentication Required',408=>'Request Timeout',409=>'Conflict',410=>'Gone',411=>'Length Required',412=>'Precondition Failed',413=>'Request Entity Too Large',414=>'Request-URI Too Long',415=>'Unsupported Media Type',416=>'Requested Range Not Satisfiable',417=>'Expectation Failed',418=>'I\'m a teapot',419=>'Authentication Timeout',420=>'Enhance Your Calm',420=>'Method Failure',422=>'Unprocessable Entity',423=>'Locked',424=>'Failed Dependency',424=>'Method Failure',425=>'Unordered Collection',426=>'Upgrade Required',428=>'Precondition Required',429=>'Too Many Requests',431=>'Request Header Fields Too Large',444=>'No Response',449=>'Retry With',450=>'Blocked by Windows Parental Controls',451=>'Redirect',451=>'Unavailable For Legal Reasons',494=>'Request Header Too Large',495=>'Cert Error',496=>'No Cert',497=>'HTTP to HTTPS',499=>'Client Closed Request',500=>'Internal Server Error',501=>'Not Implemented',502=>'Bad Gateway',503=>'Service Unavailable',504=>'Gateway Timeout',505=>'HTTP Version Not Supported',506=>'Variant Also Negotiates',507=>'Insufficient Storage',508=>'Loop Detected',509=>'Bandwidth Limit Exceeded',510=>'Not Extended',511=>'Network Authentication Required',598=>'Network read timeout error',599=>'Network connect timeout error'];

function start_webserver() {
  $SERVER_STARTUP_TIMEOUT = 1000000; // 1 second

  $pid = pcntl_fork();
  switch($pid) {
    case -1:
      die("Failed to fork webserver process\n");

    case 0:
      // exec the command
      $HANDLER = getenv('_HANDLER');
      $phpMinorVersion = PHP_MINOR_VERSION;
      $handler_components = explode('/', $HANDLER);
      $handler_filename = array_pop($handler_components);
      $handler_path = implode('/', array_merge(['/var/task'], $handler_components));
      chdir($handler_path);
      exec("PHP_INI_SCAN_DIR=/opt/etc/php-7.${phpMinorVersion}.d/:/var/task/php-7.${phpMinorVersion}.d/ php -S localhost:8000 -c /var/task/php.ini -d extension_dir=/opt/lib/php/7.${phpMinorVersion}/modules '$handler_filename'");
      exit;

    default:
      // Wait for child server to start
      $start = microtime(true);

      do {
        if (microtime(true) - $start > $SERVER_STARTUP_TIMEOUT) {
          die("Webserver failed to start within one second\n");
        }

        usleep(1000);
        $fp = @fsockopen('localhost', 8000, $errno, $errstr, 1);
      } while ($fp == false);

      fclose($fp);
  }
}

function fail($AWS_LAMBDA_RUNTIME_API, $invocation_id, $message) {
  $ch = curl_init("http://$AWS_LAMBDA_RUNTIME_API/2018-06-01/runtime/invocation/$invocation_id/response");

  $response = array();

  $response['statusCode'] = 500;
  $response['body'] = $message;

  $response_json = json_encode($response);

  curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'POST');
  curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
  curl_setopt($ch, CURLOPT_POSTFIELDS, $response_json);
  curl_setopt($ch, CURLOPT_HTTPHEADER, array(
    'Content-Type: application/json',
    'Content-Length: ' . strlen($response_json)
  ));

  curl_exec($ch);
  curl_close($ch);
}

start_webserver();

while (true) {
  $ch = curl_init("http://$AWS_LAMBDA_RUNTIME_API/2018-06-01/runtime/invocation/next");

  curl_setopt($ch, CURLOPT_FOLLOWLOCATION, TRUE);
  curl_setopt($ch, CURLOPT_FAILONERROR, TRUE);

  $invocation_id = '';

  curl_setopt($ch, CURLOPT_HEADERFUNCTION, function ($ch, $header) use (&$invocation_id) {
    if (!preg_match('/:\s*/', $header)) {
      return strlen($header);
    }

    [$name, $value] = preg_split('/:\s*/', $header, 2);

    if (strtolower($name) == 'lambda-runtime-aws-request-id') {
      $invocation_id = trim($value);
    }

    return strlen($header);
  });

  $body = '';

  curl_setopt($ch, CURLOPT_WRITEFUNCTION, function ($ch, $chunk) use (&$body) {
    $body .= $chunk;

    return strlen($chunk);
  });

  curl_exec($ch);

  if (curl_error($ch)) {
    die('Failed to fetch next Lambda invocation: ' . curl_error($ch) . "\n");
  }

  if ($invocation_id == '') {
    die("Failed to determine Lambda invocation ID\n");
  }

  curl_close($ch);

  if (!$body) {
    die("Empty Lambda invocation response\n");
  }

  $event = json_decode($body, TRUE);

  if (!array_key_exists('requestContext', $event)) {
    fail($AWS_LAMBDA_RUNTIME_API, $invocation_id, 'Event is not an API Gateway request');
    continue;
  }

  $uri = $event['path'];

  if (array_key_exists('multiValueQueryStringParameters', $event) && $event['multiValueQueryStringParameters']) {
    $first = TRUE;
    foreach ($event['multiValueQueryStringParameters'] as $name => $values) {
      foreach ($values as $value) {
        if ($first) {
          $uri .= "?";
          $first = FALSE;
        } else {
          $uri .= "&";
        }

        $uri .= $name;

        if ($value != '') {
          $uri .= '=' . $value;
        }
      }
    }
  }

  $ch = curl_init("http://localhost:8000$uri");

  curl_setopt($ch, CURLOPT_FOLLOWLOCATION, FALSE);

  if (array_key_exists('multiValueHeaders', $event)) {
    $headers = array();

    foreach ($event['multiValueHeaders'] as $name => $values) {
      foreach ($values as $value) {
        array_push($headers, "${name}: ${value}");
      }
    }

    curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
  }

  curl_setopt($ch, CURLOPT_CUSTOMREQUEST, $event['httpMethod']);

  if (array_key_exists('body', $event)) {
    $body = $event['body'];
    if (array_key_exists('isBase64Encoded', $event) && $event['isBase64Encoded']) {
      $body = base64_decode($body);
    }
  } else {
    $body = '';
  }

  if (strlen($body) > 0) {
    curl_setopt($ch, CURLOPT_POSTFIELDS, $body);
  }

  $response = array();
  $response['multiValueHeaders'] = array();
  $response['body'] = '';

  curl_setopt($ch, CURLOPT_HEADERFUNCTION, function ($ch, $header) use (&$response) {
    if (preg_match('/HTTP\/1.1 (\d+) .*/', $header, $matches)) {
      $response['statusCode'] = intval($matches[1]);
      return strlen($header);
    }

    if (!preg_match('/:\s*/', $header)) {
      return strlen($header);
    }

    [$name, $value] = preg_split('/:\s*/', $header, 2);

    $name = trim($name);
    $value = trim($value);

    if ($name == '') {
      return strlen($header);
    }

    if (!array_key_exists($name, $response['multiValueHeaders'])) {
      $response['multiValueHeaders'][$name] = array();
    }

    array_push($response['multiValueHeaders'][$name], $value);

    return strlen($header);
  });

  curl_setopt($ch, CURLOPT_WRITEFUNCTION, function ($ch, $chunk) use (&$response) {
    $response['body'] .= $chunk;

    return strlen($chunk);
  });

  curl_exec($ch);
  curl_close($ch);

  $ch = curl_init("http://$AWS_LAMBDA_RUNTIME_API/2018-06-01/runtime/invocation/$invocation_id/response");

  $isALB = array_key_exists("elb", $event['requestContext']);
  if ($isALB) { // Add Headers For ALB
    $status = $response["statusCode"];
    if (array_key_exists($status, $http_codes)) {
        $response["statusDescription"] = "$status ". $http_codes[$status];
    } else {
        $response["statusDescription"] = "$status Unknown";
    }
    $response["isBase64Encoded"] = false;
  }
  $response_json = json_encode($response);
  curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'POST');
  curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
  curl_setopt($ch, CURLOPT_POSTFIELDS, $response_json);
  if (!$isALB){
    curl_setopt($ch, CURLOPT_HTTPHEADER, array(
      'Content-Type: application/json',
      'Content-Length: ' . strlen($response_json)
    ));
  }
  curl_exec($ch);
  curl_close($ch);
}

?>