koa-router.js

/*
 * Copyright Elasticsearch B.V. and other contributors where applicable.
 * Licensed under the BSD 2-Clause License; you may not use this file except in
 * compliance with the BSD 2-Clause License.
 */

'use strict';

var semver = require('semver');

var shimmer = require('../shimmer');

module.exports = function (Router, agent, { version, enabled }) {
  if (!enabled) return Router;
  if (!semver.satisfies(version, '>=5.2.0 <=12')) {
    agent.logger.debug(
      'koa-router version %s not supported - aborting...',
      version,
    );
    return Router;
  }

  agent.logger.debug('shimming koa-router prototype.match function');
  shimmer.wrap(Router.prototype, 'match', function (orig) {
    return function (_, method) {
      var matched = orig.apply(this, arguments);

      if (typeof method !== 'string') {
        agent.logger.debug(
          'unexpected method type in koa-router prototype.match: %s',
          typeof method,
        );
        return matched;
      }

      if (Array.isArray(matched && matched.pathAndMethod)) {
        const layer = matched.pathAndMethod.find(function (layer) {
          return layer && layer.opts && layer.opts.end === true;
        });

        var path = layer && layer.path;
        if (typeof path === 'string') {
          var name = method + ' ' + path;
          agent._instrumentation.setDefaultTransactionName(name);
        } else {
          agent.logger.debug(
            'unexpected path type in koa-router prototype.match: %s',
            typeof path,
          );
        }
      } else {
        agent.logger.debug(
          'unexpected match result in koa-router prototype.match: %s',
          typeof matched,
        );
      }

      return matched;
    };
  });

  return Router;
};