Exporters

OpenTelemetryコレクターにテレメトリーを送信し、正しくエクスポートされることを確認してください。 本番環境でコレクターを使用することはベストプラクティスです。 テレメトリーを可視化するために、Jaeger、Zipkin、 Prometheus、またはベンダー固有のようなバックエンドにエクスポートしてください。

使用可能なエクスポーター

レジストリには、JavaScript 用のエクスポーターのリストが含まれています。

エクスポーターの中でも、OpenTelemetry Protocol (OTLP)エクスポーターは、OpenTelemetryのデータモデルを考慮して設計されており、OTelデータを情報の損失なく出力します。 さらに、多くのテレメトリデータを扱うツールがOTLPに対応しており（たとえば、Prometheus、Jaegerやほとんどのベンダー）、必要なときに高い柔軟性を提供します。 OTLPについて詳細に学習したい場合は、OTLP仕様を参照してください。

このページでは、主要なOpenTelemetry JavaScript エクスポーターとその設定方法について説明します。

OTLP

コレクターのセットアップ

OTLPエクスポーターを試し、検証するために、テレメトリーを直接コンソールに書き込むDockerコンテナでコレクターを実行できます。 空のディレクトリで、以下の内容でcollector-config.yamlというファイルを作成します。

receivers:
  otlp:
    protocols:
      grpc:
        endpoint: 0.0.0.0:4317
      http:
        endpoint: 0.0.0.0:4318
exporters:
  debug:
    verbosity: detailed
service:
  pipelines:
    traces:
      receivers: [otlp]
      exporters: [debug]
    metrics:
      receivers: [otlp]
      exporters: [debug]
    logs:
      receivers: [otlp]
      exporters: [debug]

次に、Docker コンテナでコレクターを実行します。

docker run -p 4317:4317 -p 4318:4318 --rm -v $(pwd)/collector-config.yaml:/etc/otelcol/config.yaml otel/opentelemetry-collector

このコレクターは、OTLPを介してテレメトリーを受け取ることができるようになりました。後で、テレメトリーを監視バックエンドに送信するためにコレクターを設定することもできます。

Dependencies

If you want to send telemetry data to an OTLP endpoint (like the OpenTelemetry Collector, Jaeger or Prometheus), you can choose between three different protocols to transport your data:

• HTTP/protobuf
• HTTP/JSON
• gRPC

Start by installing the respective exporter packages as a dependency for your project:

• HTTP/Proto
• HTTP/JSON
• gRPC

npm install --save @opentelemetry/exporter-trace-otlp-proto \
  @opentelemetry/exporter-metrics-otlp-proto

npm install --save @opentelemetry/exporter-trace-otlp-http \
  @opentelemetry/exporter-metrics-otlp-http

npm install --save @opentelemetry/exporter-trace-otlp-grpc \
  @opentelemetry/exporter-metrics-otlp-grpc

Usage with Node.js

Next, configure the exporter to point at an OTLP endpoint. For example you can update the file instrumentation.ts (or instrumentation.js if you use JavaScript) from the Getting Started like the following to export traces and metrics via OTLP (http/protobuf) :

• TypeScript
• JavaScript

/*instrumentation.ts*/
import * as opentelemetry from '@opentelemetry/sdk-node';
import { getNodeAutoInstrumentations } from '@opentelemetry/auto-instrumentations-node';
import { OTLPTraceExporter } from '@opentelemetry/exporter-trace-otlp-proto';
import { OTLPMetricExporter } from '@opentelemetry/exporter-metrics-otlp-proto';
import { PeriodicExportingMetricReader } from '@opentelemetry/sdk-metrics';

const sdk = new opentelemetry.NodeSDK({
  traceExporter: new OTLPTraceExporter({
    // optional - default url is http://localhost:4318/v1/traces
    url: '<your-otlp-endpoint>/v1/traces',
    // optional - collection of custom headers to be sent with each request, empty by default
    headers: {},
  }),
  metricReader: new PeriodicExportingMetricReader({
    exporter: new OTLPMetricExporter({
      url: '<your-otlp-endpoint>/v1/metrics', // url is optional and can be omitted - default is http://localhost:4318/v1/metrics
      headers: {}, // an optional object containing custom headers to be sent with each request
    }),
  }),
  instrumentations: [getNodeAutoInstrumentations()],
});
sdk.start();

/*instrumentation.js*/
const opentelemetry = require('@opentelemetry/sdk-node');
const {
  getNodeAutoInstrumentations,
} = require('@opentelemetry/auto-instrumentations-node');
const {
  OTLPTraceExporter,
} = require('@opentelemetry/exporter-trace-otlp-proto');
const {
  OTLPMetricExporter,
} = require('@opentelemetry/exporter-metrics-otlp-proto');
const { PeriodicExportingMetricReader } = require('@opentelemetry/sdk-metrics');

const sdk = new opentelemetry.NodeSDK({
  traceExporter: new OTLPTraceExporter({
    // optional - default url is http://localhost:4318/v1/traces
    url: '<your-otlp-endpoint>/v1/traces',
    // optional - collection of custom headers to be sent with each request, empty by default
    headers: {},
  }),
  metricReader: new PeriodicExportingMetricReader({
    exporter: new OTLPMetricExporter({
      url: '<your-otlp-endpoint>/v1/metrics', // url is optional and can be omitted - default is http://localhost:4318/v1/metrics
      headers: {}, // an optional object containing custom headers to be sent with each request
      concurrencyLimit: 1, // an optional limit on pending requests
    }),
  }),
  instrumentations: [getNodeAutoInstrumentations()],
});
sdk.start();

Usage in the Browser

When you use the OTLP exporter in a browser-based application, you need to note that:

1. Using gRPC for exporting is not supported
2. Content Security Policies (CSPs) of your website might block your exports
3. Cross-Origin Resource Sharing (CORS) headers might not allow your exports to be sent
4. You might need to expose your collector to the public internet

Below you will find instructions to use the right exporter, to configure your CSPs and CORS headers and what precautions you have to take when exposing your collector.

Use OTLP exporter with HTTP/JSON or HTTP/protobuf

OpenTelemetry Collector Exporter with gRPC works only with Node.js, therefore you are limited to use the OpenTelemetry Collector Exporter with HTTP/JSON or OpenTelemetry Collector Exporter with HTTP/protobuf.

Make sure that the receiving end of your exporter (collector or observability backend) accepts http/json if you are using OpenTelemetry Collector Exporter with HTTP/JSON, and that you are exporting your data to the right endpoint with your port set to 4318.

Configure CSPs

If your website is making use of Content Security Policies (CSPs), make sure that the domain of your OTLP endpoint is included. If your collector endpoint is https://collector.example.com:4318/v1/traces, add the following directive:

connect-src collector.example.com:4318/v1/traces

If your CSP is not including the OTLP endpoint, you will see an error message, stating that the request to your endpoint is violating the CSP directive.

Configure CORS headers

If your website and collector are hosted at a different origin, your browser might block the requests going out to your collector. You need to configure special headers for Cross-Origin Resource Sharing (CORS).

The OpenTelemetry Collector provides a feature for http-based receivers to add the required headers to allow the receiver to accept traces from a web browser:

receivers:
  otlp:
    protocols:
      http:
        include_metadata: true
        cors:
          allowed_origins:
            - https://foo.bar.com
            - https://*.test.com
          allowed_headers:
            - Example-Header
          max_age: 7200

Securely expose your collector

To receive telemetry from a web application you need to allow the browsers of your end-users to send data to your collector. If your web application is accessible from the public internet, you also have to make your collector accessible for everyone.

It is recommended that you do not expose your collector directly, but that you put a reverse proxy (NGINX, Apache HTTP Server, …) in front of it. The reverse proxy can take care of SSL-offloading, setting the right CORS headers, and many other features specific to web applications.

Below you will find a configuration for the popular NGINX web server to get you started:

server {
    listen 80 default_server;
    server_name _;
    location / {
        # Take care of preflight requests
        if ($request_method = 'OPTIONS') {
             add_header 'Access-Control-Max-Age' 1728000;
             add_header 'Access-Control-Allow-Origin' 'name.of.your.website.example.com' always;
             add_header 'Access-Control-Allow-Headers' 'Accept,Accept-Language,Content-Language,Content-Type' always;
             add_header 'Access-Control-Allow-Credentials' 'true' always;
             add_header 'Content-Type' 'text/plain charset=UTF-8';
             add_header 'Content-Length' 0;
             return 204;
        }

        add_header 'Access-Control-Allow-Origin' 'name.of.your.website.example.com' always;
        add_header 'Access-Control-Allow-Credentials' 'true' always;
        add_header 'Access-Control-Allow-Headers' 'Accept,Accept-Language,Content-Language,Content-Type' always;
        proxy_http_version 1.1;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_pass http://collector:4318;
    }
}

Console

To debug your instrumentation or see the values locally in development, you can use exporters writing telemetry data to the console (stdout).

If you followed the Getting Started or Manual Instrumentation guides, you already have the console exporter installed.

The ConsoleSpanExporter is included in the @opentelemetry/sdk-trace-node package and the ConsoleMetricExporter is included in the @opentelemetry/sdk-metrics package:

Jaeger

Backend Setup

Jaeger natively supports OTLP to receive trace data. You can run Jaeger in a docker container with the UI accessible on port 16686 and OTLP enabled on ports 4317 and 4318:

docker run --rm \
  -e COLLECTOR_ZIPKIN_HOST_PORT=:9411 \
  -p 16686:16686 \
  -p 4317:4317 \
  -p 4318:4318 \
  -p 9411:9411 \
  jaegertracing/all-in-one:latest

Usage

Now following the instruction to setup the OTLP exporters.

Prometheus

To send your metric data to Prometheus, you can either enable Prometheus’ OTLP Receiver and use the OTLP exporter or you can use the Prometheus exporter, a MetricReader that starts an HTTP server that collects metrics and serialize to Prometheus text format on request.

Backend Setup

You can run Prometheus in a docker container, accessible on port 9090 by following these instructions:

Create a file called prometheus.yml with the following content:

scrape_configs:
  - job_name: dice-service
    scrape_interval: 5s
    static_configs:
      - targets: [host.docker.internal:9464]

Run Prometheus in a docker container with the UI accessible on port 9090:

docker run --rm -v ${PWD}/prometheus.yml:/prometheus/prometheus.yml -p 9090:9090 prom/prometheus --enable-feature=otlp-write-receive

Dependencies

Install the exporter package as a dependency for your application:

npm install --save @opentelemetry/exporter-prometheus

Update your OpenTelemetry configuration to use the exporter and to send data to your Prometheus backend:

• TypeScript
• JavaScript

import * as opentelemetry from '@opentelemetry/sdk-node';
import { getNodeAutoInstrumentations } from '@opentelemetry/auto-instrumentations-node';
import { PrometheusExporter } from '@opentelemetry/exporter-prometheus';

const sdk = new opentelemetry.NodeSDK({
  metricReader: new PrometheusExporter({
    port: 9464, // optional - default is 9464
  }),
  instrumentations: [getNodeAutoInstrumentations()],
});
sdk.start();

const opentelemetry = require('@opentelemetry/sdk-node');
const {
  getNodeAutoInstrumentations,
} = require('@opentelemetry/auto-instrumentations-node');
const { PrometheusExporter } = require('@opentelemetry/exporter-prometheus');
const { PeriodicExportingMetricReader } = require('@opentelemetry/sdk-metrics');
const sdk = new opentelemetry.NodeSDK({
  metricReader: new PrometheusExporter({
    port: 9464, // optional - default is 9464
  }),
  instrumentations: [getNodeAutoInstrumentations()],
});
sdk.start();

With the above you can access your metrics at http://localhost:9464/metrics. Prometheus or an OpenTelemetry Collector with the Prometheus receiver can scrape the metrics from this endpoint.

Zipkin

Backend Setup

You can run Zipkin on in a Docker container by executing the following command:

docker run --rm -d -p 9411:9411 --name zipkin openzipkin/zipkin

Dependencies

To send your trace data to Zipkin, you can use the ZipkinExporter.

Install the exporter package as a dependency for your application:

npm install --save @opentelemetry/exporter-zipkin

Update your OpenTelemetry configuration to use the exporter and to send data to your Zipkin backend:

• TypeScript
• JavaScript

import * as opentelemetry from '@opentelemetry/sdk-node';
import { getNodeAutoInstrumentations } from '@opentelemetry/auto-instrumentations-node';
import { ZipkinExporter } from '@opentelemetry/exporter-zipkin';

const sdk = new opentelemetry.NodeSDK({
  traceExporter: new ZipkinExporter({}),
  instrumentations: [getNodeAutoInstrumentations()],
});
sdk.start();

const opentelemetry = require('@opentelemetry/sdk-node');
const {
  getNodeAutoInstrumentations,
} = require('@opentelemetry/auto-instrumentations-node');
const { ZipkinExporter } = require('@opentelemetry/exporter-zipkin');

const sdk = new opentelemetry.NodeSDK({
  traceExporter: new ZipkinExporter({}),
  instrumentations: [getNodeAutoInstrumentations()],
});

Custom exporters

Finally, you can also write your own exporter. For more information, see the SpanExporter Interface in the API documentation.

Batching span and log records

The OpenTelemetry SDK provides a set of default span and log record processors, that allow you to either emit spans one-by-on (“simple”) or batched. Using batching is recommended, but if you do not want to batch your spans or log records, you can use a simple processor instead as follows:

• TypeScript
• JavaScript

/*instrumentation.ts*/
import * as opentelemetry from '@opentelemetry/sdk-node';
import { getNodeAutoInstrumentations } from '@opentelemetry/auto-instrumentations-node';

const sdk = new NodeSDK({
  spanProcessors: [new SimpleSpanProcessor(exporter)],
  instrumentations: [getNodeAutoInstrumentations()],
});
sdk.start();

/*instrumentation.js*/
const opentelemetry = require('@opentelemetry/sdk-node');
const {
  getNodeAutoInstrumentations,
} = require('@opentelemetry/auto-instrumentations-node');

const sdk = new opentelemetry.NodeSDK({
  spanProcessors: [new SimpleSpanProcessor(exporter)],
  instrumentations: [getNodeAutoInstrumentations()],
});
sdk.start();