skyapm-nodejs/lib/agent.js

The Node server instrument SDK for Apache SkyWalking

/*
 * Licensed to the SkyAPM under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 */

"use strict";

const Instrumentation = require("./instrumentation");
const ContextManager = require("./trace/context-manager");
const PluginManager = require("./plugins/plugin-manager");
const serviceManager = require("./services");
const AgentConfig = require("./config");
module.exports = Agent;

/**
 * @author zhang xin
 */
function Agent() {
    this._instrumentation = null;
    this._contextManager = null;
}

Agent.prototype.start = function(agentOptions) {
    if (!!process.env.SW_ENABLED && process.env.SW_ENABLED !== "true") {
        console.info("SW_ENABLED != true, the agent won't start");
        return;
    }
    AgentConfig.initConfig(agentOptions);
    serviceManager.launch();

    this._contextManager = new ContextManager();
    this._instrumentation = new Instrumentation();

    let _pluginManager = new PluginManager();
    let _agent = this;
    require("./require-module-hook")(_pluginManager.allEnhanceModules(),
        function(originModule, moduleName, version, enhanceFile) {
            let intercept = _pluginManager.attemptToFindInterceptor(moduleName, version, enhanceFile);

            if (intercept === undefined) {
                return originModule;
            }

            return intercept(originModule, _agent._instrumentation,
                _agent._contextManager);
        });
};