src/plugins/plugin-connect.ts

// Copyright 2015 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

import {IncomingMessage, ServerResponse} from 'http';
// eslint-disable-next-line n/no-deprecated-api
import {parse as urlParse} from 'url';

import {PluginTypes} from '..';

import {connect_3} from './types';

type Connect3 = typeof connect_3;
// Connect docs note that routed requests have an originalUrl property.
// https://github.com/senchalabs/connect/tree/3.6.5#appuseroute-fn
type Request = IncomingMessage & {originalUrl?: string};

const SUPPORTED_VERSIONS = '3.x';

function createMiddleware(
  api: PluginTypes.Tracer
): connect_3.NextHandleFunction {
  return function middleware(req: Request, res, next) {
    const options = {
      name: req.originalUrl ? urlParse(req.originalUrl).pathname || '' : '',
      url: req.originalUrl,
      method: req.method,
      traceContext: api.propagation.extract(key => req.headers[key]),
      skipFrames: 1,
    };
    api.runInRootSpan(options, root => {
      // Set response trace context.
      const responseTraceContext = api.getResponseTraceContext(
        options.traceContext,
        api.isRealSpan(root)
      );
      if (responseTraceContext) {
        api.propagation.inject(
          (k, v) => res.setHeader(k, v),
          responseTraceContext
        );
      }

      if (!api.isRealSpan(root)) {
        return next();
      }

      api.wrapEmitter(req);
      api.wrapEmitter(res);

      const url = `${req.headers['X-Forwarded-Proto'] || 'http'}://${
        req.headers.host
      }${req.originalUrl}`;

      // we use the path part of the url as the span name and add the full
      // url as a label
      root.addLabel(api.labels.HTTP_METHOD_LABEL_KEY, req.method);
      root.addLabel(api.labels.HTTP_URL_LABEL_KEY, url);
      root.addLabel(api.labels.HTTP_SOURCE_IP, req.connection.remoteAddress);

      // wrap end
      const originalEnd = res.end;
      res.end = function (this: ServerResponse) {
        res.end = originalEnd;
        // eslint-disable-next-line prefer-rest-params
        const returned = res.end.apply(this, arguments);

        root.addLabel('connect/request.route.path', req.originalUrl);
        root.addLabel(api.labels.HTTP_RESPONSE_CODE_LABEL_KEY, res.statusCode);
        root.endSpan();

        return returned;
      };

      next();
    });
  };
}

const plugin: PluginTypes.Plugin = [
  {
    file: '',
    versions: SUPPORTED_VERSIONS,
    intercept: (connect, api) => {
      return function (this: {}) {
        const app = connect();
        app.use(createMiddleware(api));
        return app;
      };
    },
  } as PluginTypes.Intercept<Connect3>,
];

export = plugin;