Trace Python, Node.js, and Java Lambda functions

Dynatrace provides you with a dedicated AWS Lambda layer that contains the Dynatrace extension for AWS Lambda. You need to add the publicly available layer for your runtime and region to your function. Then, based on your configuration method, Dynatrace provides a template or configuration for your AWS Lambda function.

Activate AWS Lambda

Choose a configuration method

Specify a Dynatrace API endpoint

Enable Real User Monitoring

Define an AWS layer name

Deployment

Configuration options

Dynatrace AWS integration

Prerequisites

• A supported AWS Lambda runtime. The Dynatrace extension supports AWS Lambda functions written in Node.js, Python, or Java. Both 64-bit ARM (AWS Graviton2 processors) and 64-bit x86 architectures are supported.
• Java The following RAM requirements need to be met:
  • If Lambda SnapStart is enabled and OneAgent version is 1.267+, memory needs to be set to a minimum of 512 MB.
  • If Lambda SnapStart is not enabled and OneAgent version is 1.265 or earlier, memory needs to be set to a minimum of 1500 MB. To configure memory in the AWS Lambda console, go to General > Basic settings and set Memory.

  A new configuration of the memory size affects the amount of virtual CPU available to the function; to learn more about it, see Monitoring overhead below.

  • Note that the RAM requirements for Node.js and Python Lambda functions might be significantly lower.
• Activate the Forward Tag 4 trace context extension OneAgent feature. In the Dynatrace menu, go to Settings > Preferences > OneAgent features.

Activate AWS Lambda

To get started

1. In the Dynatrace menu, select Deploy Dynatrace.
2. On the Dynatrace Hub page, search for AWS Lambda.
3. Select AWS Lambda and then select Activate AWS Lambda.
4. Follow the instructions to enable monitoring of AWS Lambda functions.

Choose a configuration method

The Dynatrace Lambda agent is distributed as a layer that can be enabled and configured manually or using well known Infrastructure as Code (IaC) solutions.

On the Enable Monitoring for AWS Lambda Functions page, use the How will you configure your AWS Lambda functions? list to select your preferred method, and then make sure you set all properties for the selected method before copying the generated configuration snippets.

Specify a Dynatrace API endpoint optional

This is an optional step that enables you to specify a Dynatrace API endpoint to which monitoring data will be sent.

The typical scenario is to deploy a Dynatrace ActiveGate in close proximity (same region) to the Lambda functions that you want to monitor in order to reduce network latency, which can impact the startup time of your Lambda functions.

Enable Real User Monitoring optional

This is an optional step to use Real User Monitoring (RUM), which provides you with deep insights into user actions and performance via the browser or in mobile apps.

Configure AWS

• Make sure the x-dtc header is allowed in the CORS settings of your monitored Lambda functions.

  RUM for Lambda functions requires a specific header (x-dtc) to be sent with XHR calls to AWS. To enable it, the CORS settings of your AWS deployment must allow the x-dtc header during preflight (OPTIONS) requests. To configure CORS and allow the x-dtc header for your specific setup, see Enable CORS on a resource using the API Gateway console in AWS documentation.

Configure Dynatrace

To configure the x-dtc header for calls to your Lambda functions

1. In the Dynatrace menu, select Web, Mobile, Frontend, or Custom applications, depending on your application type.
2. Select the application you want to connect with your Lambda function.
3. Select the browse menu (…) in the upper-right corner and select Edit.
4. Select Capturing > Async web requests and SPAs.
5. Make sure that your framework of choice is enabled. If your framework is not listed, enable Capture XmlHttpRequest (XHR) for generic support of XHR.
6. Select Capturing > Advanced setup.
7. Scroll down to the Enable Real User Monitoring for cross-origin XHR calls section and enter a pattern that matches the URL to your Lambda functions. For example: TheAwsUniqueId.execute-api.us-east-1.amazonaws.com
8. Select Save. After a few minutes, the header will be attached to all calls to your Lambda function and requests from your browser will be linked to the backend.

Define an AWS layer name

Select the AWS region and the runtime of the Lambda function to be monitored. These settings are required to provide the correct layer ARN.

Deployment

Copy the configuration snippets into your deployment and use your deployment method of choice to enable the layer and set the configuration for your Lambda functions.

Configuration options

Configure the AWS API Gateway

If inbound (non-XHR) requests to your Lambda functions are not connected to the calling application, configure the API Gateway to pass through the Dynatrace tag. To do this, enable Use Lambda Proxy Integration on the Integration Request configuration page of the API Gateway.

AWS Lambda also supports non-proxy integration, which, without some additional configuration, prevents Dynatrace from

• Tracing calls from other monitored applications
• RUM detection (web and mobile)

Node.jsPython To make tracing calls from other monitored applications/RUM detection work in this scenario, create a custom mapping template in the integration requests configuration.

1. In the AWS API Gateway Console, go to Resources and select a request method (for example, GET).

2. Select Mapping Templates and then select Add mapping template.

3. Add the following content to the template:

   jsoncopydownload
   {
       "path": "$context.path",
       "httpMethod": "$context.httpMethod",
       "headers": {
           #foreach($param in ["x-dynatrace", "traceparent", "tracestate", "x-dtc", "referer", "host", "x-forwarded-proto", "x-forwarded-for", "x-forwarded-port"])
           "$param": "$util.escapeJavaScript($input.params().header.get($param))"
           #if($foreach.hasNext),#end
           #end    },
       "requestContext": {
           "stage": "$context.stage"
       }
   }

   The x-dtc header is specific to tracing RUM scenarios, whereas the remaining headers are generally needed to link traces together and extract relevant information, such as web request metadata.

4. Select Save to save your configuration.

5. Redeploy your API.

Filter cold starts

One of the important metrics for Lambda is the frequency of cold starts. A cold start happens when a new instance of a Lambda function is invoked. Such cold starts take longer and add latency to your requests.

A high cold-start frequency can indicate errors or an uneven load pattern that can be mitigated using provisioned concurrency. Dynatrace reports such cold starts as a property on the distributed trace.

To analyze cold starts, select View all requests on the Lambda service details page.

In the request filter, select Function cold start in the Request property section.

This displays a page that you can filter by invocations containing Only cold start or No cold start.

Monitoring overhead

Enabling monitoring unavoidably induces overhead to the monitored function execution. Overhead depends on several factors, such as function runtime technology, configuration, and concrete function characteristics such as code size or execution duration and complexity.

The amount of memory configured for a function directly impacts the compute resources assigned to the function instance. For more details, see Memory and computing power.

The worst-case scenario on measured overhead is a function with an empty function handler and minimum memory configuration.

Cold start overhead

• For Python, cold start overhead is about 1,000 ms.
• For Node.js, cold start overhead is about 700 ms.
• For Java, cold start overhead may exceed 1,000 ms.

For the minimum memory configuration requirement, see Requirement for Java Lambda functions.

Response time latency

Latency depends on the function implementation, but is typically less than 10%.

Code space overhead

Dynatrace AWS integration

While not mandatory, we recommend that you set up Dynatrace Amazon CloudWatch integration. This allows data ingested via AWS integration to be seamlessly combined with the data collected by the Dynatrace AWS Lambda extension.

Known limitations

• The Dynatrace AWS Lambda extension does not support the capture of method-level request attributes.

• Most Dynatrace AWS Lambda extensions don't capture IP addresses of outgoing HTTP requests. This results in unmonitored hosts if the called service isn't monitored with Dynatrace.

• Incoming calls: Dynatrace can monitor incoming calls only if they are invoked via:

  • AWS SDK Lambda Invoke API
  • API gateway
  • AWS SQS
  • AWS SNS For other invocation types, OneAgent cannot capture any specific information and can also not connect the trace to any parent.

• Outgoing requests to another AWS Lambda function: In a monitored AWS Lambda function, the following libraries are supported for outgoing requests to another AWS Lambda function:

  • For Java - AWS SDK version 1 for Java
  • For Node.js - AWS SDK for JavaScript in Node.js:
    • version 2
    • version 3 (OneAgent version 1.263+)
  • For Python - AWS SDK for Python (Boto3)

• Outgoing HTTP requests: In a monitored AWS Lambda function, the following libraries/HTTP clients are supported for outgoing HTTP requests:

  • For Java - Apache HTTP Client 3.x, 4.x
  • For Node.js - The built-in http.request
  • For Python - requests, aiohttp-client, urllib3

• Additional requirements for incoming calls for Java only: To correctly monitor the configured handler method

  • The configured handler class has to implement the handler method by itself. If the handler method is only defined in a base class, you have to add an override in the handler class, calling the base handler method within (usually super.handleRequest(...)).
  • The handler method has to have a Context (com.amazonaws.services.lambda.runtime.Context) parameter.
  • We recommend following best practice by deriving your Lambda handler class from com.amazonaws.services.lambda.runtime.RequestHandler overrriding handleRequest and configuring that as handler method. However, as long as the previous requirements are fulfilled, the agent supports any valid handler function, even if not derived from that base interface.
  • The AWS Lambda events library must be used by your function as the types defined in the com.amazonaws.services.lambda.runtime.events package are used by OneAgent to match the corresponding invocation types for incoming calls.