Amazon Lambda

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Overview

Amazon Lambda is a compute service that runs code in response to events and automatically manages the compute resources required by that code.

Enable this integration to begin collecting CloudWatch metrics. This page also describes how to set up custom metrics, logging, and tracing for your Lambda functions.

Setup

Installation

If you haven’t already, set up the Amazon Web Services integration first.

Metric collection

1. In the AWS integration tile, ensure that Lambda is checked under metric collection.

2. Add the following permissions to your Datadog IAM policy to collect Amazon Lambda metrics. For more information on Lambda policies, review the documentation on the AWS website.

   AWS Permission	Description
   lambda:List*	List Lambda functions, metadata, and tags.
   tag:GetResources	Get custom tags applied to Lambda functions.

3. Install the Datadog - AWS Lambda integration.

Once this is completed, view all of your Lambda Functions in the Datadog Serverless view. This page brings together metrics, traces, and logs from your AWS Lambda functions running serverless applications into one view. Detailed documentation on this feature can be found in the Datadog Serverless documentation.

Tagging metrics

Any tag applied to your Lambda function automatically becomes a new dimension on which your can slice and dice your metrics.

AWS Step Functions integration

Enable the AWS Step Functions integration to automatically get additional tags on your Lambda metrics identifying which state machines particular functions belong to. Use this to get an aggregated view of your Lambda metrics per Step Function, and see your Step Functions on the Serverless view.

Real-time enhanced Lambda metrics

Datadog generates real-time Lambda runtime metrics out-of-the-box for Node.js, Python, and Ruby runtimes.

Using the Datadog Lambda Layers and Lambda Forwarder, Datadog can generate metrics with low latency, several second granularity, and detailed metadata for cold starts and custom tags.

These metrics are tagged with the functionname, cold_start, region, account_id, allocated_memory, and runtime. These are DISTRIBUTION type metrics, so you can display their count, min, max, sum, and avg.

Enabling enhanced real-time Lambda metrics

1. Set up or update the Datadog Forwarder to at least version 2.3.1.
2. Install the the Datadog Lambda Layer on the functions for which you’d like these metrics (Layer version 9+ for Python, Layer version 6+ for Node.js, Layer version 5+ for Ruby, package version 0.5.0+ for Go).
3. Optional - Set the DD_FLUSH_TO_LOG to true on your functions to flush the enhanced metrics asynchronously through logs.
4. To automatically tag these metrics with custom tags applied to your function, set the DD_FETCH_LAMBDA_TAGS env variable to true on the Datadog Lambda Forwarder. And add the tag:GetResources permission to your function (not to your Datadog Lambda Forwarder).
5. Browse to the Enhanced Lambda Metrics Default Dashboard.

Note: These metrics are enabled by default, but only get sent asynchronously. They are sent to the Datadog Lambda Forwarder via CloudWatch Logs, meaning you’ll see an increased volume of logs in CloudWatch. This may affect your AWS bill. To opt out, set the DD_ENHANCED_METRICS environment variable to false on your AWS Lambda functions.

The invocation and error metrics get generated by the Datadog Lambda Layer, and the others are generated by the Datadog Lambda Forwarder.

Datadog Lambda Layer

The Datadog Lambda Layer is responsible for:

• Generating real-time enhanced Lambda metrics for invocations, errors, cold starts, etc.
• Submitting custom metrics (synchronously and asynchronously)
• Automatically propagating tracing headers from upstream requests to downstream services. This enables full distributed tracing across Lambda functions, hosts, containers, and other infrastructure running the Datadog Agent.

Installing and using the Datadog Lambda Layer

Datadog offers Lambda Layers for Python, Node.js, and Ruby. Go is also supported with a package to include in your project. Datadog is working on support for new languages and runtimes; if there is another runtime you would like Datadog to support, reach out to the Datadog support team.

The Datadog Lambda Layer ARN includes a region, language runtime, and version. Construct yours in the following format:

arn:aws:lambda:<AWS_REGION>:464622532012:layer:Datadog-<RUNTIME>:<VERSION>

For example:

arn:aws:lambda:us-east-1:464622532012:layer:Datadog-Python37:11

Golang: Since Go binaries are statically-linked, Datadog offers a package you can simply import in your project. No Lambda Layer is required.

Note: The Datadog Lambda Layer and client libraries include the X-Ray SDK as a dependency, so you don’t need to explicitly install it in your projects.

You can configure the Datadog Lambda Layer by adding environment variables to your Lambda functions:

npm install --save-dev serverless-plugin-datadog  # for NPM users
yarn add --dev serverless-plugin-datadog          # for Yarn users

plugins:
    - serverless-plugin-datadog

custom:
    datadog:
        # (Required) Datadog API Key, only necessary
        # when using synchronous custom metrics
        apiKey: '<DATADOG_API_KEY>'

        # (Optional) Encrypted Datadog API Key (if using KMS)
        apiKMSKey: ''

        # (Optional) Controls if the plugin should
        # add the Datadog Lambda Layers automatically
        #  Default: true
        #  Options: true, false
        addLayers: true

        # (Optional) Which Datadog instance to send data to
        #  Default: datadoghq.com
        #  Options: datadoghq.com, datadoghq.eu
        site: datadoghq.com

        # (Optional) Controls if asynchronous custom metric
        # submission is enabled by default
        #  Default: false
        #  Options: true, false
        flushMetricsToLogs: false

        # (Optional) The log level of the Datadog
        # plugin and Lambda Layers
        #  Default: "INFO"
        #  Options: INFO, DEBUG
        logLevel: 'INFO'

Globals:
    Function:
        Tracing: Active
        Environment:
            Variables:
                DD_API_KEY: YOUR_DATADOG_API_KEY
    Api:
        TracingEnabled: true

Local development

You can also include the Datadog Lambda package directly in your project either from source or with the standard package manager for your runtime.

Note: AWS SAM supports downloading Lambda Layers for local development.

Log collection

1. Set up the Datadog log collection AWS Lambda function if you haven’t already.

2. Once the Lambda function is installed, there are two ways to forward your Lambda logs to Datadog:

   • Automatic: We manage the log collection Lambda triggers for you if you grant us a set of permissions. Refer to the main Amazon web service to configure the automatic log collection
   • Manual: Manually add a trigger on the Cloudwatch log group that contains your Lambda logs in the AWS console following these steps

Once done, go to your Datadog Log section to start exploring your logs.

Trace collection

Datadog supports distributed tracing for your AWS Lambda functions using either Datadog APM or AWS X-Ray. You can use either set of client libraries to generate traces, and Datadog APM will connect traces from applications running on hosts, containers, and serverless functions automatically.

Visualize your traces on the Serverless page, in App Analytics, and on the Service Map. Detailed documentation for setting up this integration can be found below and on the Datadog X-Ray integration page.

Note: Enabling the AWS X-Ray integration increases the amount of consumed Analyzed Spans which can impact your bill.

Tracing with Datadog APM

The Datadog Node.js tracing library supports distributed tracing for AWS Lambda, with more runtimes coming soon. To get started:

yarn add dd-trace@dev
yarn add datadog-lambda-js

npm install dd-trace@dev
npm install datadog-lambda-js

You can then initialize and run your code like the following:

const { datadog } = require('datadog-lambda-js');
const tracer = require('dd-trace').init(); // Any manual tracer config goes here.

// This function will be wrapped in a span
const longCalculation = tracer.wrap('calculation-long-number', () => {
    // An expensive calculation goes here
});

// This function will also be wrapped in a span
module.exports.hello = datadog((event, context, callback) => {
    longCalculation();

    callback(null, {
        statusCode: 200,
        body: 'Hello from serverless!'
    });
});

If you have already configured the AWS X-Ray integration, you can optionally merge your Datadog APM traces with the corresponding AWS X-Ray trace when they reach Datadog. Use the mergeDatadogXrayTraces option with your wrapper:

module.exports.hello = datadog(
    (event, context, callback) => {
        longCalculation();

        callback(null, {
            statusCode: 200,
            body: 'Hello from serverless!'
        });
    },
    { mergeDatadogXrayTraces: true }
);

Tracing across AWS Lambda and hosts

When applicable, Datadog merges AWS X-Ray traces with native Datadog APM traces. This means that your traces will show the complete picture of requests that cross infrastructure boundaries, whether it be AWS Lambda, containers, on-prem hosts, or managed services.

1. Enable the AWS X-Ray integration for tracing your Lambda functions.
2. Add the Datadog Lambda Layer to your Lambda functions.
3. Set up Datadog APM on your hosts and container-based infrastructure.

Note: For X-Ray and Datadog APM traces to appear in the same flame graph, all services must have the same env tag.

Organizing your infrastructure with tags

Any tag applied to your Lambda function automatically becomes a new dimension on which your can slice and dice your traces.

Tags are especially powerful in Datadog APM, the Service Map, and the Services List, which have first-class support for the env and service tags.

The env tag

Use env to separate out your staging, development, and production environments. This works for any kind of infrastructure, not just for your serverless functions. As an example, you could tag your production EU Lambda functions with env:prod-eu.

By default, Lambda functions are tagged with env:none in Datadog. Add your own tag to override this.

The service tag

Add the service tag in order to group related Lambda functions into a service. The Service Map and Services List use this tag to show relationships between services and the health of their monitors. Services are represented as individual nodes on the Service Map.

By default, each Lambda function is treated as its own service. Add your own tag to override this.

Custom metrics

Install the Datadog Lambda Layer to collect and send custom metrics. Metrics sent from the Datadog Lambda Layer are automatically aggregated into distributions, so you can graph the avg, sum, max, min, and count. You can also calculate aggregations over a set of tags for the 50th, 75th, 95th, and 99th percentile values on the Distribution Metrics page.

Distribution metrics are designed to instrument logical objects, like services, independent of the underlying hosts. So, they are well-suited for serverless infrastructure because they aggregate metrics server-side instead of locally with an Agent.

Upgrading to distribution metrics

With distribution metrics, you select the aggregation when graphing or querying it instead of specifying it at submission time.

If you previously submitted custom metrics from Lambda without using one of the Datadog Lambda Layers, you’ll need to start instrumenting your custom metrics under new metric names when submitting them to Datadog. The same metric name cannot simultaneously exist as both distribution and non-distribution metric type.

To enable percentile aggregations for your distribution metrics, consult the Distribution Metrics page.

Tagging custom metrics

You should tag your custom metrics when submitting them with the Datadog Lambda Layer. Use the Distribution Metrics page to customize the set of tags applied to your custom metrics.

Synchronous vs. asynchronous custom metrics

The Datadog Lambda Layer supports submitting custom metrics in Lambda both synchronously and asynchronously.

Synchronous: The default behavior. This method submits your custom metrics to Datadog via HTTP periodically (every 10 seconds) and at the end of your Lambda invocation. So if the invocation lasts for less than 10 seconds, your custom metrics will be submitted at the end of the invocation.

Asynchronous (recommended): It’s possible to submit your custom metrics with zero latency overhead and have them appear in Datadog in near-real time. To accomplish this, the Lambda Layer emits your custom metrics as a specially-formatted log line, which the Datadog Forwarder Lambda Function parses and submits to Datadog. Logging in AWS Lambda is 100% asynchronous, so this method ensures there is zero latency overhead to your function.

Enabling asynchronous custom metrics

1. Set the environment variable DD_FLUSH_TO_LOG to True on your Lambda function.
2. Update your Datadog Forwarder Lambda Function to at least version 1.4.0.

If you are not using Datadog Logs, you can still use asynchronous custom metric submission. Set the environment variable DD_FORWARD_LOG to False on the Datadog log collection AWS Lambda function. This intelligently forwards only custom metrics to Datadog, and not regular logs.

Custom metrics sample code

In your function code, you must import the necessary methods from the Lambda Layer and add a wrapper around your function handler. You do not need to wrap your helper functions.

Note: The arguments to the custom metrics reporting methods have the following requirements:

• <METRIC_NAME> uniquely identifies your metric and adheres to the metric naming policy.
• <METRIC_VALUE> MUST be a number (i.e. integer or float).
• <TAG_LIST> is optional and formatted, for example: ['owner:Datadog', 'env:demo', 'cooltag'].

from datadog_lambda.metric import lambda_metric
from datadog_lambda.wrapper import datadog_lambda_wrapper

# You only need to wrap your function handler (Not helper functions). 
@datadog_lambda_wrapper
def lambda_handler(event, context):
    lambda_metric(
        "coffee_house.order_value",             # Metric name
        12.45,                                  # Metric value
        tags=['product:latte', 'order:online']  # Associated tags
    )

const { datadog, sendDistributionMetric } = require('datadog-lambda-js');

async function myHandler(event, context) {
    sendDistributionMetric(
        'coffee_house.order_value', // Metric name
        12.45, // Metric value
        'product:latte',
        'order:online' // Associated tags
    );
    return {
        statusCode: 200,
        body: 'hello, dog!'
    };
}
// You only need to wrap your function handler (Not helper functions).
module.exports.myHandler = datadog(myHandler);

/* OR with manual configuration options
module.exports.myHandler = datadog(myHandler, {
    apiKey: "my-api-key"
});
*/

package main

import (
  "github.com/aws/aws-lambda-go/lambda"
  "github.com/DataDog/datadog-lambda-go"
)

func main() {
  // You only need to wrap your function handler (Not helper functions). 
  lambda.Start(ddlambda.WrapHandler(myHandler, nil))
  /* OR with manual configuration options
  lambda.Start(ddlambda.WrapHandler(myHandler, &ddlambda.Config{
    BatchInterval: time.Second * 15
    APIKey: "my-api-key",
  }))
  */
}

func myHandler(ctx context.Context, event MyEvent) (string, error) {
  ddlambda.Distribution(
    "coffee_house.order_value",     // Metric name
    12.45,                          // Metric value
    "product:latte", "order:online" // Associated tags
  )
  // ...
}

require 'datadog/lambda'

def handler(event:, context:)
    # You only need to wrap your function handler (Not helper functions).
    Datadog::Lambda.wrap(event, context) do
        Datadog::Lambda.metric(
          'coffee_house.order_value',         # Metric name
          12.45,                              # Metric value
          "product":"latte", "order":"online" # Associated tags
        )
        return { statusCode: 200, body: 'Hello World' }
    end
end

{
    "m": "coffee_house.order_value",
    "v": 12.45,
    "e": 1572273854,
    "t": ["product:latte", "order:online"]
}

Running in a VPC

The Datadog Lambda Layer requires access to the public internet in order to submit custom metrics synchronously. If your Lambda function is associated with a VPC, ensure that it is instead submitting custom metrics asynchronously or that your function can reach the public internet.

Using Third-Party Libraries

There are a number of open source libraries that make it easy to submit custom metrics to Datadog. However, many have not been updated to use Distribution metrics, which are optimized for Lambda. Distribution metrics allow for server-side aggregations independent of a host or locally-running agent. In a serverless environment where there is no agent, Distribution metrics give you flexible aggregations and tagging.

When evaluating third-party metrics libraries for AWS Lambda, ensure they support Distribution metrics.

[DEPRECATED] Using CloudWatch Logs

This method of submitting custom metrics is no longer supported, and is disabled for all new customers. The recommended way to submit custom metrics from Lambda is with a Datadog Lambda Layer.

This requires the following AWS permissions in your Datadog IAM policy.

[DEPRECATED] To send custom metrics to Datadog from your Lambda logs, print a log line using the following format:

MONITORING|<UNIX_EPOCH_TIMESTAMP>|<METRIC_VALUE>|<METRIC_TYPE>|<METRIC_NAME>|#<TAG_LIST>

Where:

• MONITORING signals to the Datadog integration that it should collect this log entry.
• <UNIX_EPOCH_TIMESTAMP> is in seconds, not milliseconds.
• <METRIC_VALUE> MUST be a number (i.e. integer or float).
• <METRIC_TYPE> is count, gauge, histogram, or check.
• <METRIC_NAME> uniquely identifies your metric and adheres to the metric naming policy.
• <TAG_LIST> is optional, comma separated, and must be preceded by #. The tag function_name:<name_of_the_function> is automatically applied to custom metrics.

Note: The sum for each timestamp is used for counts and the last value for a given timestamp is used for gauges. It is not recommended to print a log statement every time you increment a metric, as this increases the time it takes to parse your logs. Continually update the value of the metric in your code, and print one log statement for that metric before the function finishes.

Data Collected

Metrics

Each of the metrics retrieved from AWS is assigned the same tags that appear in the AWS console, including but not limited to function name, security-groups, and more.

Custom metrics are only tagged with function name.

Events

The AWS Lambda integration does not include any events.

Service Checks

The AWS Lambda integration does not include any service checks.

Troubleshooting

Need help? Contact Datadog support.

Further Reading

Additional helpful documentation, links, and articles:

How to monitor Lambda functionsBLOG Datadog's Lambda Layer: Monitor custom serverless metricsBLOG