Instrumenting Node.js Applications
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Instrumenting Node.js Applications

Required Setup

If not already configured:

After you have installed the AWS integration and the Datadog Forwarder, follow these steps to instrument your application to send metrics, logs, and traces to Datadog.

Configuration

The Datadog Serverless Plugin automatically adds the Datadog Lambda library to your functions using layers, and configures your functions to send metrics, traces, and logs to Datadog through the Datadog Forwarder.

To install and configure the Datadog Serverless Plugin, follow these steps:

  1. Install the Datadog Serverless Plugin:
    yarn add --dev serverless-plugin-datadog
    
  2. In your serverless.yml, add the following:
    plugins:
      - serverless-plugin-datadog
    
  3. In your serverless.yml, also add the following section:
    custom:
      datadog:
        forwarder: # The Datadog Forwarder ARN goes here.
    

    More information on the Datadog Forwarder ARN or installation can be found here. For additional settings, see the plugin documentation.

This service is in public beta. If you have any feedback, contact Datadog support.

The Datadog CloudFormation macro automatically transforms your SAM application template to add the Datadog Lambda library to your functions using layers, and configure your functions to send metrics, traces, and logs to Datadog through the Datadog Forwarder.

Install the Datadog CloudFormation Macro

Run the following command with your AWS credentials to deploy a CloudFormation stack that installs the macro AWS resource. You only need to install the macro once for a given region in your account. Replace create-stack with update-stack to update the macro to the latest version.

aws cloudformation create-stack \
  --stack-name datadog-serverless-macro \
  --template-url https://datadog-cloudformation-template.s3.amazonaws.com/aws/serverless-macro/latest.yml \
  --capabilities CAPABILITY_AUTO_EXPAND CAPABILITY_IAM

The macro is now deployed and ready to use.

Instrument the Function

In your template.yml, add the following under the Transform section, after the AWS::Serverless transform for SAM.

Transform:
  - AWS::Serverless-2016-10-31
  - Name: DatadogServerless
    Parameters:
      stackName: !Ref "AWS::StackName"
      nodeLayerVersion: "<LAYER_VERSION>"
      forwarderArn: "<FORWARDER_ARN>"
      service: "<SERVICE>" # Optional
      env: "<ENV>" # Optional

Replace <SERVICE> and <ENV> with appropriate values, <LAYER_VERSION> with the desired version of Datadog Lambda layer (see the latest releases), and <FORWARDER_ARN> with Forwarder ARN (see the Forwarder documentation).

More information and additional parameters can be found in the macro documentation.

This service is in public beta. If you have any feedback, contact Datadog support.

The Datadog CloudFormation macro automatically transforms the CloudFormation template generated by the AWS CDK to add the Datadog Lambda library to your functions using layers, and configure your functions to send metrics, traces, and logs to Datadog through the Datadog Forwarder.

Install the Datadog CloudFormation Macro

Run the following command with your AWS credentials to deploy a CloudFormation stack that installs the macro AWS resource. You only need to install the macro once for a given region in your account. Replace create-stack with update-stack to update the macro to the latest version.

aws cloudformation create-stack \
  --stack-name datadog-serverless-macro \
  --template-url https://datadog-cloudformation-template.s3.amazonaws.com/aws/serverless-macro/latest.yml \
  --capabilities CAPABILITY_AUTO_EXPAND CAPABILITY_IAM

The macro is now deployed and ready to use.

Instrument the Function

Add the DatadogServerless transform and the CfnMapping to your Stack object in your AWS CDK app. See the sample code below in TypeScript (the usage in other language should be similar).

import * as cdk from "@aws-cdk/core";

class CdkStack extends cdk.Stack {
  constructor(scope: cdk.Construct, id: string, props?: cdk.StackProps) {
    super(scope, id, props);
    this.addTransform("DatadogServerless");

    new cdk.CfnMapping(this, "Datadog", {
      mapping: {
        Parameters: {
          nodeLayerVersion: "<LAYER_VERSION>",
          forwarderArn: "<FORWARDER_ARN>",
          stackName: this.stackName,
          service: "<SERVICE>", // Optional
          env: "<ENV>", // Optional
        },
      },
    });
  }
}

Replace <SERVICE> and <ENV> with appropriate values, <LAYER_VERSION> with the desired version of Datadog Lambda layer (see the latest releases), and <FORWARDER_ARN> with Forwarder ARN (see the Forwarder documentation).

More information and additional parameters can be found in the macro documentation.

This service is in public beta. If you have any feedback, contact Datadog support.

Use the Datadog CLI to set up instrumentation on your Lambda functions in your CI/CD pipelines. The CLI command automatically adds the Datadog Lambda library to your functions using layers, and configures your functions to send metrics, traces, and logs to Datadog.

Install the Datadog CLI

Install the Datadog CLI with NPM or Yarn:

# NPM
npm install -g @datadog/datadog-ci

# Yarn
yarn global add @datadog/datadog-ci

Instrument the Function

Run the following command with your AWS credentials. Replace <functionname> and <another_functionname> with your Lambda function names, <aws_region> with the AWS region name, <layer_version> with the desired version of the Datadog Lambda layer (see latest releases) and <forwarder_arn> with Forwarder ARN (see the Forwarder documentation).

datadog-ci lambda instrument -f <functionname> -f <another_functionname> -r <aws_region> -v <layer_version> --forwarder	<forwarder_arn>

For example:

datadog-ci lambda instrument -f my-function -f another-function -r us-east-1 -v 26 --forwarder arn:aws:lambda:us-east-1:000000000000:function:datadog-forwarder

More information and additional parameters can be found in the CLI documentation.

Install the Datadog Lambda Library

If you are deploying your Lambda function as a container image, you cannot use the Datadog Lambda Library as a layer. Instead, you must install the Datadog Lambda Library directly within the image. If you are using Datadog tracing, you must also install dd-trace.

NPM:

npm install --save datadog-lambda-js dd-trace

Yarn:

yarn add datadog-lambda-js dd-trace

Note that the minor version of the datadog-lambda-js package always matches the layer version. For example, datadog-lambda-js v0.5.0 matches the content of layer version 5.

Configure the function

  1. Set your image’s CMD value to node_modules/datadog-lambda-js/dist/handler.handler. You can either set this directly in your Dockerfile or override the value using AWS.
  2. Set the environment variable DD_LAMBDA_HANDLER to your original handler, for example, myfunc.handler.
  3. Set the environment variable DD_TRACE_ENABLED to true.
  4. Set the environment variable DD_FLUSH_TO_LOG to true.
  5. Optionally add a service and env tag with appropriate values to your function.

Subscribe the Datadog Forwarder to the log groups

You need to subscribe the Datadog Forwarder Lambda function to each of your functions’ log groups in order to send metrics, traces, and logs to Datadog.

  1. Install the Datadog Forwarder if you haven’t.
  2. Subscribe the Datadog Forwarder to your function’s log groups.

Install the Datadog Lambda Library

The Datadog Lambda Library can be imported as a layer or JavaScript package.

The minor version of the datadog-lambda-js package always matches the layer version. E.g., datadog-lambda-js v0.5.0 matches the content of layer version 5.

Using the Layer

Configure the layers for your Lambda function using the ARN in the following format.

# For regular regions
arn:aws:lambda:<AWS_REGION>:464622532012:layer:Datadog-<RUNTIME>:<VERSION>

# For us-gov regions
arn:aws-us-gov:lambda:<AWS_REGION>:002406178527:layer:Datadog-<RUNTIME>:<VERSION>

The available RUNTIME options are Node8-10, Node10-x, and Node12-x. For VERSION, see the latest release. For example:

arn:aws:lambda:us-east-1:464622532012:layer:Datadog-Node12-x:25

Using the Package

NPM:

npm install --save datadog-lambda-js

Yarn:

yarn add datadog-lambda-js

See the latest release.

Configure the Function

  1. Set your function’s handler to /opt/nodejs/node_modules/datadog-lambda-js/handler.handler if using the layer, or node_modules/datadog-lambda-js/dist/handler.handler if using the package.
  2. Set the environment variable DD_LAMBDA_HANDLER to your original handler, for example, myfunc.handler.
  3. Set the environment variable DD_TRACE_ENABLED to true.
  4. Set the environment variable DD_FLUSH_TO_LOG to true.
  5. Optionally add a service and env tag with appropriate values to your function.

Subscribe the Datadog Forwarder to the Log Groups

You need to subscribe the Datadog Forwarder Lambda function to each of your function’s log groups, in order to send metrics, traces, and logs to Datadog.

  1. Install the Datadog Forwarder if you haven’t.
  2. Subscribe the Datadog Forwarder to your function’s log groups.

Explore Datadog Serverless Monitoring

After you have configured your function following the steps above, you can view metrics, logs and traces on the Serverless Homepage.

Monitor Custom Business Logic

If you would like to submit a custom metric or span, see the sample code below:

const { sendDistributionMetric, sendDistributionMetricWithDate } = require("datadog-lambda-js");
const tracer = require("dd-trace");

// submit a custom span named "sleep"
const sleep = tracer.wrap("sleep", (ms) => {
  return new Promise((resolve) => setTimeout(resolve, ms));
});

exports.handler = async (event) => {
  // add custom tags to the lambda function span,
  // does NOT work when X-Ray tracing is enabled
  const span = tracer.scope().active();
  span.setTag('customer_id', '123456');

  await sleep(100);

  // submit a custom span
  const sandwich = tracer.trace('hello.world', () => {
    console.log('Hello, World!');
  });

  // submit a custom metric
  sendDistributionMetric(
    "coffee_house.order_value", // metric name
    12.45, // metric value
    "product:latte", // tag
    "order:online", // another tag
  );

  // submit a custom metric with timestamp
  sendDistributionMetricWithDate(
    "coffee_house.order_value", // metric name
    12.45, // metric value
    new Date(Date.now()), // date, must be within last 20 mins
    "product:latte", // tag
    "order:online", // another tag
  );

  const response = {
    statusCode: 200,
    body: JSON.stringify("Hello from serverless!"),
  };
  return response;
};

For more information on custom metric submission, see here. For additional details on custom instrumentation, see the Datadog APM documentation for custom instrumentation.

Further Reading