Instrumenting .NET Serverless Applications

Docs > Serverless > Serverless Monitoring for AWS Lambda > Install Serverless Monitoring for AWS Lambda > Instrumenting .NET Serverless Applications

If your Lambda functions are deployed in VPC without access to the public internet, you can send data either using AWS PrivateLink for the datadoghq.com Datadog site, or using a proxy for all other sites.

Installation

Datadog offers many different ways to enable instrumentation for your serverless applications. Choose a method below that best suits your needs. Datadog generally recommends using the Datadog CLI. You must follow the instructions for “Container Image” if your application is deployed as a container image.

The Datadog CLI modifies existing Lambda functions’ configurations to enable instrumentation without requiring a new deployment. It is the quickest way to get started with Datadog’s serverless monitoring.

Install the Datadog CLI client
```
npm install -g @datadog/datadog-ci
```
If you are new to Datadog serverless monitoring, launch the Datadog CLI in interactive mode to guide your first installation for a quick start, and you can ignore the remaining steps. To permanently install Datadog for your production applications, skip this step and follow the remaining ones to run the Datadog CLI command in your CI/CD pipelines after your normal deployment.
```
datadog-ci lambda instrument -i
```
Configure the AWS credentials
The Datadog CLI requires access to the AWS Lambda service and depends on the AWS JavaScript SDK to resolve the credentials. Ensure your AWS credentials are configured using the same method you would use when invoking the AWS CLI.
Configure the Datadog site
```
export DATADOG_SITE="<DATADOG_SITE>"
```
Replace <DATADOG_SITE> with (ensure the correct SITE is selected on the right).
Configure the Datadog API key
Datadog recommends saving the Datadog API key in AWS Secrets Manager for security and easy rotation. The key needs to be stored as a plaintext string (not a JSON blob). Ensure your Lambda functions have the required secretsmanager:GetSecretValue IAM permission.
```
export DATADOG_API_KEY_SECRET_ARN="<DATADOG_API_KEY_SECRET_ARN>"
```
For quick testing purposes, you can also set the Datadog API key in plaintext:
```
export DATADOG_API_KEY="<DATADOG_API_KEY>"
```
Instrument your Lambda functions
Note: Instrument your Lambda functions in a dev or staging environment first! Should the instrumentation result be unsatisfactory, run uninstrument with the same arguments to revert the changes.
To instrument your Lambda functions, run the following command.
```
datadog-ci lambda instrument -f <functionname> -f <another_functionname> -r <aws_region> -v 15 -e 56
```
To fill in the placeholders:
- Replace <functionname> and <another_functionname> with your Lambda function names. Alternatively, you can use --functions-regex to automatically instrument multiple functions whose names match the given regular expression.
- Replace <aws_region> with the AWS region name.
Additional parameters can be found in the CLI documentation.

The Datadog Serverless Plugin automatically configures your functions to send metrics, traces, and logs to Datadog through the Datadog Lambda Extension.

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

Install the Datadog Serverless Plugin:

serverless plugin install --name serverless-plugin-datadog

Update your serverless.yml:
```
custom:
  datadog:
    site: <DATADOG_SITE>
    apiKeySecretArn: <DATADOG_API_KEY_SECRET_ARN>
```
To fill in the placeholders:
- Replace <DATADOG_SITE> with (ensure the correct SITE is selected on the right).
- Replace <DATADOG_API_KEY_SECRET_ARN> with the ARN of the AWS secret where your Datadog API key is securely stored. The key needs to be stored as a plaintext string (not a JSON blob). The secretsmanager:GetSecretValue permission is required. For quick testing, you can instead use apiKey and set the Datadog API key in plaintext.
For more information and additional settings, see the plugin documentation.

The Datadog CloudFormation macro automatically transforms your SAM application template to install Datadog on your functions using Lambda layers, and configures your functions to send metrics, traces, and logs to Datadog through the Datadog Lambda Extension.

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 your Lambda functions
Add the DatadogServerless transform after the AWS::Serverless transform under the Transform section in your template.yml file for SAM.
```
Transform:
  - AWS::Serverless-2016-10-31
  - Name: DatadogServerless
    Parameters:
      stackName: !Ref "AWS::StackName"
      dotnetLayerVersion: 15
      extensionLayerVersion: 56
      site: "<DATADOG_SITE>"
      apiKeySecretArn: "<DATADOG_API_KEY_SECRET_ARN>"
```
To fill in the placeholders:
- Replace <DATADOG_SITE> with (ensure the correct SITE is selected on the right).
- Replace <DATADOG_API_KEY_SECRET_ARN> with the ARN of the AWS secret where your Datadog API key is securely stored. The key needs to be stored as a plaintext string (not a JSON blob). The secretsmanager:GetSecretValue permission is required. For quick testing, you can use apiKey instead and set the Datadog API key in plaintext.
More information and additional parameters can be found in the macro documentation.

Install the Datadog Lambda Extension
```
COPY --from=public.ecr.aws/datadog/lambda-extension:<TAG> /opt/. /opt/
```
Replace <TAG> with either a specific version number (for example, 56) or with latest. Alpine is also supported with specific version numbers (such as 56-alpine) or with latest-alpine. You can see a complete list of possible tags in the Amazon ECR repository.

Install the Datadog .NET APM client

RUN yum -y install tar wget gzip
RUN wget https://github.com/DataDog/dd-trace-dotnet/releases/download/v<TRACER_VERSION>/datadog-dotnet-apm-<TRACER_VERSION>.tar.gz
RUN mkdir /opt/datadog
RUN tar -C /opt/datadog -xzf datadog-dotnet-apm-<TRACER_VERSION>.tar.gz
ENV AWS_LAMBDA_EXEC_WRAPPER /opt/datadog_wrapper

Replace <TRACER_VERSION> with the version number of dd-trace-dotnet you would like to use (for example, 2.3.0). The minimum supported version is 2.3.0. You can see the latest versions of dd-trace-dotnet in GitHub.

Set the required environment variables
- Set the environment variable DD_SITE to (ensure the correct SITE is selected on the right).
- Set the environment variable DD_API_KEY_SECRET_ARN with the ARN of the AWS secret where your Datadog API key is securely stored. The key needs to be stored as a plaintext string (not a JSON blob). The secretsmanager:GetSecretValue permission is required. For quick testing, you can use DD_API_KEY instead and set the Datadog API key in plaintext.

Use this format for your Terraform resource:

resource "aws_lambda_function" "lambda" {
  "function_name" = ...
  ...

  # Remember sure to choose the right layers based on your Lambda architecture and AWS regions

  layers = [
    <DATADOG_TRACER_ARN>,
    <DATADOG_EXTENSION_ARN>
  ]

  environment {
    variables = {
      DD_SITE                     = <DATADOG_SITE>
      DD_API_KEY_SECRET_ARN       = <API_KEY>
      AWS_LAMBDA_EXEC_WRAPPER     = "/opt/datadog_wrapper"
    }
  }
}

Fill in variables accordingly:

Replace <DATADOG_TRACER_ARN> with the ARN of the appropriate Datadog tracer for your region and architecture:

AWS REGIONS	ARCHITECTURE	LAYER
Commercial	x86_64	`arn:aws:lambda:<AWS_REGION>:464622532012:layer:dd-trace-dotnet:15`
Commercial	arm64	`arn:aws:lambda:<AWS_REGION>:464622532012:layer:dd-trace-dotnet-ARM:15`
GovCloud	x86_64	`arn:aws:lambda:<AWS_REGION>:002406178527:layer:dd-trace-dotnet:15`
GovCloud	arm64	`arn:aws:lambda:<AWS_REGION>:002406178527:layer:dd-trace-dotnet-ARM:15`

In the ARN, replace <AWS_REGION> with a valid AWS region, such as us-east-1.

Replace <DATADOG_EXTENSION_ARN> with the ARN of the appropriate Datadog Lambda Extension for your region and architecture:

AWS REGIONS	ARCHITECTURE	LAYER
Commercial	x86_64	`arn:aws:lambda:<AWS_REGION>:464622532012:layer:Datadog-Extension:56`
Commercial	arm64	`arn:aws:lambda:<AWS_REGION>:464622532012:layer:Datadog-Extension-ARM:56`
GovCloud	x86_64	`arn:aws-us-gov:lambda:<AWS_REGION>:002406178527:layer:Datadog-Extension:56`
GovCloud	arm64	`arn:aws-us-gov:lambda:<AWS_REGION>:002406178527:layer:Datadog-Extension-ARM:56`

In the ARN, replace <AWS_REGION> with a valid AWS region, such as us-east-1.

Replace <DATADOG_SITE> with (ensure the correct SITE is selected on the right).
Replace <API_KEY> with the ARN of the AWS secret where your Datadog API key is securely stored. The key needs to be stored as a plaintext string (not a JSON blob). The secretsmanager:GetSecretValue permission is required. For quick testing, use DD_API_KEY instead of DD_API_KEY_SECRET_ARN and set the value to your Datadog API key in plaintext.

Full example

resource "aws_lambda_function" "lambda" {
  "function_name" = ...
  ...

  # Remember sure to choose the right layers based on your Lambda architecture and AWS regions

  layers = [
    "arn:aws:lambda:us-east-1:464622532012:layer:dd-trace-dotnet:15",
    "arn:aws:lambda:us-east-1:464622532012:layer:Datadog-Extension:56"
  ]


  environment {
    variables = {
      DD_SITE                     = "datadoghq.com"
      DD_API_KEY_SECRET_ARN       = "arn:aws..."
      AWS_LAMBDA_EXEC_WRAPPER     = "/opt/datadog_wrapper"
    }
  }
}

Install the Datadog Tracer

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

# Use this format for x86-based Lambda deployed in AWS commercial regions
arn:aws:lambda:<AWS_REGION>:464622532012:layer:dd-trace-dotnet:15

# Use this format for arm64-based Lambda deployed in AWS commercial regions
arn:aws:lambda:<AWS_REGION>:464622532012:layer:dd-trace-dotnet-ARM:15

# Use this format for x86-based Lambda deployed in AWS GovCloud regions
arn:aws-us-gov:lambda:<AWS_REGION>:002406178527:layer:dd-trace-dotnet:15

# Use this format for arm64-based Lambda deployed in AWS GovCloud regions
arn:aws-us-gov:lambda:<AWS_REGION>:002406178527:layer:dd-trace-dotnet-ARM:15

Replace <AWS_REGION> with a valid AWS region, such as us-east-1.

Install the Datadog Lambda Extension