go

Instrumented Go Lambda

This is a "Hello, World" style Lambda function in Go, instrumented with the New Relic Agent.

This example is both instructive, and a diagnostic tool: if you can deploy this Lambda function, and see its events in NR One, you'll know that all the telemetry plumbing is connected correctly.

Building and deploying

Prerequisites

• The AWS CLI v2
• Go
• newrelic-lambda CLI tool

Make sure you've run the newrelic-lambda install command in your AWS Region, and included the --enable-license-key-secret flag.

deploy script

From a command prompt, in this directory, run

./deploy.sh <accountId> <region>

where <accountId> is your New Relic account ID and <region> is your AWS Region, like "us-west-2".

This will compile, package and deploy the CloudFormation stack for this example function.

At this point, you can invoke the function. As provided, the example function doesn't pay attention to its invocation event. If everything has gone well, each invocation gets reported to New Relic, and its telemetry appears in NR One.

Code Structure

Now is also a good time to look at the structure of the example code.

template.yaml

This function is deployed using a SAM template, which is a CloudFormation template with some extra syntactic sugar for Lambda functions. In it, we tell CloudFormation where to find the handler zip, what layers to use, and what IAM policies to add to the Lambda function's execution role.

main.go

Lambda functions written in Go are whole executable processes. They start at main() just like any Go program. The included Lambda libraries do the work of interfacing with the AWS Lambda service, to fetch new events and send responses. The New Relic Agent wraps the Lambda library, and collects telemetry.

There are a couple examples here of how you might add custom events and attributes to the default telemetry.

Since Go is a compiled language, the Agent can't automatically modify the various database and network clients your function might be using, so you'll want to manually wrap interesting parts of your function code in segments.