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Node.js

本页将向您展示如何在 Node.js 中开始使用 OpenTelemetry。

您将学习如何自动检测一个简单的应用程序，以一种 将traces、metrics和logs发送到控制台的方式。

先决条件

确保在本地安装了以下软件:

示例应用程序

下面的示例使用一个基本的Express应用程序。如果你不使用 Express，没关系——你也可以将 OpenTelemetry JavaScript 与其他 web 框架一起使用，比 如 Koa 和 Nest.JS。要获得支持框架的完整库列表，请参 见registry。

有关更详细的示例，请参见示例.

依赖关系

首先，在新目录中设置一个空的package.json:

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npm init -y

接下来，安装 Express 依赖项。

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npm install typescript \
  ts-node \
  @types/node \
  express \
  @types/express

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npm install express

创建并启动 HTTP 服务器

Create a file named app.ts (or app.js if not using typescript) and add the following code to it:

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/*app.ts*/
import express, { Express } from 'express';

const PORT: number = parseInt(process.env.PORT || '8080');
const app: Express = express();

function getRandomNumber(min: number, max: number) {
  return Math.floor(Math.random() * (max - min) + min);
}

app.get('/rolldice', (req, res) => {
  res.send(getRandomNumber(1, 6).toString());
});

app.listen(PORT, () => {
  console.log(`Listening for requests on http://localhost:${PORT}`);
});

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/*app.js*/
const express = require('express');

const PORT = parseInt(process.env.PORT || '8080');
const app = express();

function getRandomNumber(min, max) {
  return Math.floor(Math.random() * (max - min) + min);
}

app.get('/rolldice', (req, res) => {
  res.send(getRandomNumber(1, 6).toString());
});

app.listen(PORT, () => {
  console.log(`Listening for requests on http://localhost:${PORT}`);
});

Run the application with the following command and open http://localhost:8080/rolldice in your web browser to ensure it is working.

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$ npx ts-node app.ts
Listening for requests on http://localhost:8080

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$ node app.js
Listening for requests on http://localhost:8080

插装

The following shows how to install, initialize, and run an application instrumented with OpenTelemetry.

依赖

First, install the Node SDK and autoinstrumentations package.

The Node SDK lets you initialize OpenTelemetry with several configuration defaults that are correct for the majority of use cases.

The auto-instrumentations-node package installs instrumentation packages that will automatically create spans corresponding to code called in libraries. In this case, it provides instrumentation for Express, letting the example app automatically create spans for each incoming request.

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npm install @opentelemetry/sdk-node \
  @opentelemetry/api \
  @opentelemetry/auto-instrumentations-node \
  @opentelemetry/sdk-metrics

To find all autoinstrumentation modules, you can look at the registry.

设置

The instrumentation setup and configuration must be run before your application code. One tool commonly used for this task is the --require flag.

Create a file named instrumentation.ts (or instrumentation.js if not using typescript) , which will contain your instrumentation setup code.

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/*instrumentation.ts*/
import { NodeSDK } from '@opentelemetry/sdk-node';
import { ConsoleSpanExporter } from '@opentelemetry/sdk-trace-node';
import { getNodeAutoInstrumentations } from '@opentelemetry/auto-instrumentations-node';
import {
  PeriodicExportingMetricReader,
  ConsoleMetricExporter,
} from '@opentelemetry/sdk-metrics';

const sdk = new NodeSDK({
  traceExporter: new ConsoleSpanExporter(),
  metricReader: new PeriodicExportingMetricReader({
    exporter: new ConsoleMetricExporter(),
  }),
  instrumentations: [getNodeAutoInstrumentations()],
});

sdk.start();

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/*instrumentation.js*/
// Require dependencies
const { NodeSDK } = require('@opentelemetry/sdk-node');
const { ConsoleSpanExporter } = require('@opentelemetry/sdk-trace-node');
const {
  getNodeAutoInstrumentations,
} = require('@opentelemetry/auto-instrumentations-node');
const {
  PeriodicExportingMetricReader,
  ConsoleMetricExporter,
} = require('@opentelemetry/sdk-metrics');

const sdk = new NodeSDK({
  traceExporter: new ConsoleSpanExporter(),
  metricReader: new PeriodicExportingMetricReader({
    exporter: new ConsoleMetricExporter(),
  }),
  instrumentations: [getNodeAutoInstrumentations()],
});

sdk.start();

运行插装应用

现在你可以像平常一样运行你的应用程序了，但是你可以使用--require标志在加载应用 程序代码之前加载工具。

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$ npx ts-node --require ./instrumentation.ts app.ts
Listening for requests on http://localhost:8080

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$ node --require ./instrumentation.js app.js
Listening for requests on http://localhost:8080

在你的网页浏览器中打开http://localhost:8080/rolldice重新加载页面几次。过了一会 儿，你应该会看到控制台通过ConsoleSpanExporter打印出 spans。

查看示例输出 
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{
  "traceId": "3f1fe6256ea46d19ec3ca97b3409ad6d",
  "parentId": "f0b7b340dd6e08a7",
  "name": "middleware - query",
  "id": "41a27f331c7bfed3",
  "kind": 0,
  "timestamp": 1624982589722992,
  "duration": 417,
  "attributes": {
    "http.route": "/",
    "express.name": "query",
    "express.type": "middleware"
  },
  "status": { "code": 0 },
  "events": []
}
{
  "traceId": "3f1fe6256ea46d19ec3ca97b3409ad6d",
  "parentId": "f0b7b340dd6e08a7",
  "name": "middleware - expressInit",
  "id": "e0ed537a699f652a",
  "kind": 0,
  "timestamp": 1624982589725778,
  "duration": 673,
  "attributes": {
    "http.route": "/",
    "express.name": "expressInit",
    "express.type": "middleware"
  },
  "status": { code: 0 },
  "events": []
}
{
  "traceId": "3f1fe6256ea46d19ec3ca97b3409ad6d",
  "parentId": "f0b7b340dd6e08a7",
  "name": "request handler - /",
  "id": "8614a81e1847b7ef",
  "kind": 0,
  "timestamp": 1624982589726941,
  "duration": 21,
  "attributes": {
    "http.route": "/",
    "express.name": "/",
    "express.type": "request_handler"
  },
  "status": { code: 0 },
  "events": []
}
{
  "traceId": "3f1fe6256ea46d19ec3ca97b3409ad6d",
  "parentId": undefined,
  "name": "GET /",
  "id": "f0b7b340dd6e08a7",
  "kind": 1,
  "timestamp": 1624982589720260,
  "duration": 11380,
  "attributes": {
    "http.url": "http://localhost:8080/",
    "http.host": "localhost:8080",
    "net.host.name": "localhost",
    "http.method": "GET",
    "http.route": "",
    "http.target": "/",
    "http.user_agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.114 Safari/537.36",
    "http.flavor": "1.1",
    "net.transport": "ip_tcp",
    "net.host.ip": "::1",
    "net.host.port": 8080,
    "net.peer.ip": "::1",
    "net.peer.port": 61520,
    "http.status_code": 304,
    "http.status_text": "NOT MODIFIED"
  },
  "status": { "code": 1 },
  "events": []
}

生成的 span 跟踪到/rolldice路由的请求的生命周期。

再向端点发送几个请求。稍后，您将在控制台输出中看到指标，如下所示:

查看示例输出 
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{
  descriptor: {
    name: 'http.server.duration',
    type: 'HISTOGRAM',
    description: 'measures the duration of the inbound HTTP requests',
    unit: 'ms',
    valueType: 1
  },
  dataPointType: 0,
  dataPoints: [
    {
      attributes: [Object],
      startTime: [Array],
      endTime: [Array],
      value: [Object]
    }
  ]
}
{
  descriptor: {
    name: 'http.client.duration',
    type: 'HISTOGRAM',
    description: 'measures the duration of the outbound HTTP requests',
    unit: 'ms',
    valueType: 1
  },
  dataPointType: 0,
  dataPoints: []
}
{
  descriptor: {
    name: 'db.client.connections.usage',
    type: 'UP_DOWN_COUNTER',
    description: 'The number of connections that are currently in the state referenced by the attribute "state".',
    unit: '{connections}',
    valueType: 1
  },
  dataPointType: 3,
  dataPoints: []
}
{
  descriptor: {
    name: 'http.server.duration',
    type: 'HISTOGRAM',
    description: 'measures the duration of the inbound HTTP requests',
    unit: 'ms',
    valueType: 1
  },
  dataPointType: 0,
  dataPoints: [
    {
      attributes: [Object],
      startTime: [Array],
      endTime: [Array],
      value: [Object]
    }
  ]
}
{
  descriptor: {
    name: 'http.client.duration',
    type: 'HISTOGRAM',
    description: 'measures the duration of the outbound HTTP requests',
    unit: 'ms',
    valueType: 1
  },
  dataPointType: 0,
  dataPoints: []
}
{
  descriptor: {
    name: 'db.client.connections.usage',
    type: 'UP_DOWN_COUNTER',
    description: 'The number of connections that are currently in the state referenced by the attribute "state".',
    unit: '{connections}',
    valueType: 1
  },
  dataPointType: 3,
  dataPoints: []
}
{
  descriptor: {
    name: 'http.server.duration',
    type: 'HISTOGRAM',
    description: 'measures the duration of the inbound HTTP requests',
    unit: 'ms',
    valueType: 1
  },
  dataPointType: 0,
  dataPoints: [
    {
      attributes: [Object],
      startTime: [Array],
      endTime: [Array],
      value: [Object]
    }
  ]
}
{
  descriptor: {
    name: 'http.client.duration',
    type: 'HISTOGRAM',
    description: 'measures the duration of the outbound HTTP requests',
    unit: 'ms',
    valueType: 1
  },
  dataPointType: 0,
  dataPoints: []
}
{
  descriptor: {
    name: 'db.client.connections.usage',
    type: 'UP_DOWN_COUNTER',
    description: 'The number of connections that are currently in the state referenced by the attribute "state".',
    unit: '{connections}',
    valueType: 1
  },
  dataPointType: 3,
  dataPoints: []
}

下一个步骤

Enrich your instrumentation generated automatically with manual instrumentation of your own codebase. This gets you customized observability data.

You'll also want to configure an appropriate exporter to export your telemetry data to one or more telemetry backends.

故障排除

出什么问题了吗?你可以启用诊断日志来验证 OpenTelemetry 是否被正确初始化:

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/*instrumentation.ts*/
import { diag, DiagConsoleLogger, DiagLogLevel } from '@opentelemetry/api';

// For troubleshooting, set the log level to DiagLogLevel.DEBUG
diag.setLogger(new DiagConsoleLogger(), DiagLogLevel.INFO);

// const sdk = new NodeSDK({...

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/*instrumentation.js*/
// Require dependencies
const { diag, DiagConsoleLogger, DiagLogLevel } = require('@opentelemetry/api');

// For troubleshooting, set the log level to DiagLogLevel.DEBUG
diag.setLogger(new DiagConsoleLogger(), DiagLogLevel.INFO);

// const sdk = new NodeSDK({...