Automatic instrumentation with OpenTelemetry for Node.js applications

著者

Bahubali Shetti

observability-launch-series-1-node-js-auto_(1).jpg

DevOps and SRE teams are transforming the process of software development. While DevOps engineers focus on efficient software applications and service delivery, SRE teams are key to ensuring reliability, scalability, and performance. These teams must rely on a full-stack observability solution that allows them to manage and monitor systems and ensure issues are resolved before they impact the business.  

Observability across the entire stack of modern distributed applications requires data collection, processing, and correlation often in the form of dashboards. Ingesting all system data requires installing agents across stacks, frameworks, and providers — a process that can be challenging and time-consuming for teams who have to deal with version changes, compatibility issues, and proprietary code that doesn't scale as systems change.      

Thanks to OpenTelemetry (OTel), DevOps and SRE teams now have a standard way to collect and send data that doesn't rely on proprietary code and have a large support community reducing vendor lock-in.  

In a previous blog, we also reviewed how to use the OpenTelemetry demo and connect it to Elastic®, as well as some of Elastic’s capabilities with OpenTelemetry and Kubernetes. 

In this blog, we will show how to use automatic instrumentation for OpenTelemetry with the Node.js service of our application called Elastiflix, which helps highlight auto-instrumentation in a simple way.

The beauty of this is that there is no need for the otel-collector! This setup enables you to slowly and easily migrate an application to OTel with Elastic according to a timeline that best fits your business.

Application, prerequisites, and config

The application that we use for this blog is called Elastiflix, a movie streaming application. It consists of several micro-services written in .NET, NodeJS, Go, and Python.

Before we instrument our sample application, we will first need to understand how Elastic can receive the telemetry data.

options

All of Elastic Observability’s APM capabilities are available with OTel data. Some of these include:

  • Service maps
  • Service details (latency, throughput, failed transactions)
  • Dependencies between services, distributed tracing
  • Transactions (traces)
  • Machine learning (ML) correlations
  • Log correlation

In addition to Elastic’s APM and a unified view of the telemetry data, you will also be able to use Elastic’s powerful machine learning capabilities to reduce the analysis, and alerting to help reduce MTTR.

Prerequisites

View the example source code

The full source code, including the Dockerfile used in this blog, can be found on GitHub. The repository also contains the same application without instrumentation. This allows you to compare each file and see the differences.

The following steps will show you how to instrument this application and run it on the command line or in Docker. If you are interested in a more complete OTel example, take a look at the docker-compose file here, which will bring up the full project.

Step-by-step guide

Step 0. Log in to your Elastic Cloud account

This blog assumes you have an Elastic Cloud account — if not, follow the instructions to get started on Elastic Cloud.

free trial

Step 1. Configure auto-instrumentation for the Node.js Service

We are going to use automatic instrumentation with Node.js service from the Elastiflix demo application.

We will be using the following service from Elastiflix:

Elastiflix/node-server-otel-manual

Per the OpenTelemetry JavaScript documentation and @open-telemetry/auto-instrumentions-node documentation, you will simply install the appropriate node packages using npm.

npm install --save @opentelemetry/api
npm install --save @opentelemetry/auto-instrumentations-node

If you are running the Node.js service on the command line, then here is how you can run auto-instrument with Node.js.

node --require '@opentelemetry/auto-instrumentations-node/register' app.js

For our application, we do this as part of the Dockerfile.

Dockerfile

FROM node:14

WORKDIR /app

COPY ["package.json", "./"]
RUN ls
RUN npm install --production
COPY . .

RUN npm install --save @opentelemetry/api
RUN npm install --save @opentelemetry/auto-instrumentations-node


EXPOSE 3001

CMD ["node", "--require", "@opentelemetry/auto-instrumentations-node/register", "index.js"]

Step 2. Running the Docker image with environment variables

As specified in the OTEL documentation, we will use environment variables and pass in the configuration values to enable it to connect with Elastic Observability’s APM server.  

Because Elastic accepts OTLP natively, we just need to provide the Endpoint and authentication where the OTEL Exporter needs to send the data, as well as some other environment variables.

Getting Elastic Cloud variables
You can copy the endpoints and token from Kibana® under the path /app/home#/tutorial/apm.

apm agents

You will need to copy the following environment variables:

OTEL_EXPORTER_OTLP_ENDPOINT
OTEL_EXPORTER_OTLP_HEADERS

Build the image

docker build -t  node-otel-auto-image .

Run the image

docker run \    
       -e OTEL_EXPORTER_OTLP_ENDPOINT="<REPLACE WITH OTEL_EXPORTER_OTLP_ENDPOINT>" \
       -e OTEL_EXPORTER_OTLP_HEADERS="Authorization=Bearer <REPLACE WITH TOKEN>" \
       -e OTEL_RESOURCE_ATTRIBUTES="service.version=1.0,deployment.environment=production" \
       -e OTEL_SERVICE_NAME="node-server-otel-auto" \
       -p 3001:3001 \
       node-server-otel-auto

You can now issue a few requests in order to generate trace data. Note that these requests are expected to return an error, as this service relies on some downstream services that you may not have running on your machine.

curl localhost:3001/api/login
curl localhost:3001/api/favorites

# or alternatively issue a request every second

while true; do curl "localhost:3001/api/favorites"; sleep 1; done;

Step 3: Explore traces, metrics, and logs in Elastic APM

Exploring the Services section in Elastic APM, you’ll see the Node service displayed.

services

Clicking on the node-server-otel-auto service, you can see that it is ingesting telemetry data using OpenTelemetry.

Summary

In this blog, we discussed the following:

  • How to auto-instrument Node.js with OpenTelemetry
  • Using standard commands in a Dockerfile, auto-instrumentation was done efficiently and without adding code in multiple places enabling manageability

Since Elastic can support a mix of methods for ingesting data, whether it be using auto-instrumentation of open-source OpenTelemetry or manual instrumentation with its native APM agents, you can plan your migration to OTel by focusing on a few applications first and then using OpenTelemety across your applications later on in a manner that best fits your business needs.

Additional resources for OpenTelemetry with Elastic:

Developer resources:


General configuration and use case resources:

Don’t have an Elastic Cloud account yet? Sign up for Elastic Cloud and try out the auto-instrumentation capabilities that I discussed above. I would be interested in getting your feedback about your experience in gaining visibility into your application stack with Elastic.

The release and timing of any features or functionality described in this post remain at Elastic's sole discretion. Any features or functionality not currently available may not be delivered on time or at all.

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