New Relic Go Agent

The New Relic Go Agent is used to monitor Go applications by tracking transactions, outbound requests, database calls, and other application behaviors. It also provides runtime visibility into garbage collection, goroutine activity, and memory usage.

Because Go is a compiled language without a virtual machine, instrumentation requires using the New Relic Go agent API to manually add methods to your source code. This provides high flexibility and control over what is instrumented. For a more automated setup, you can use the go-easy-instrumentation CLI tool to analyze your code and suggest instrumentation points.

The zerologWriter library provides an io.Writer implementation that automatically integrates New Relic Logs in Context features with Zerolog. It collects log metrics, forwards logs, and enriches them with New Relic metadata based on your application configuration. This is the recommended way to capture log data when using Zerolog.

// Create a new ZerologWriter instance
// os.Stdout is the destination for the final log content
// app is your pointer to the New Relic application
writer := zerologWriter.New(os.Stdout, app)

There are three primary ways to get data into New Relic using this agent:

1. Manual Instrumentation: Use the Go agent API to add specific methods to your source code for maximum control.
2. Basic Runtime Monitoring: Even without manual instrumentation, simply importing the agent and creating an application instance will provide runtime information such as goroutine counts, garbage collection statistics, and memory/CPU usage.
3. Integration Packages: Use the available INTEGRATION packages for out-of-the-box support for popular Go web frameworks and libraries.

Utilization tests verify that the Go agent gathers the correct information for pricing purposes. These tests validate the JSON generated by the agents by comparing input values against an expected_output_json.

Each test case is represented as a JSON block containing specific fields that the agent is expected to calculate or detect from the environment.

The New Relic Go Agent provides specialized integration packages that extend the core newrelic package to support specific frameworks, databases, and libraries. These packages automate instrumentation for inbound requests, outbound calls, and datastore operations.

To use an integration, you must import both the core newrelic package and the specific integration package (e.g., v3/integrations/nrgin).

// Example pattern for using an integration (based on nrgin documentation)
import (
	"github.com/newrelic/go-agent/v3/newrelic"
	"github.com/newrelic/go-agent/v3/integrations/nrgin"
	"github.com/gin-gonic/gin"
)

Synthetics tests verify that the Go agent correctly handles New Relic Synthetics requests. The testing lifecycle simulates a web transaction with the following flow:

1. Request Initiation: A Synthetics HTTP request header is added to the incoming request.
2. External Request: During the transaction, an external request is made.
3. Completion: Upon transaction completion, a Transaction Trace and a Transaction Event are recorded.

Tests validate that for valid requests, the correct attributes are added to the Trace and Event, and the proper request header is added to outbound external requests. For invalid requests, tests verify that these attributes and headers are not added.

The event_source_info test fixture is used to verify that the New Relic Go Agent correctly detects event types (specifically in languages with dynamic typing) and accurately harvests AWS ARN values from Lambda invocation events.

Each fixture is a JSON object containing three specific keys:

• expected_type: The event type the agent is expected to identify (e.g., alb).
• expected_arn: The AWS ARN value the agent should extract from the event.
• event: The raw AWS Lambda invocation event object used for testing.

The top-level key in the JSON object is a <type_key> used for organizational convenience during testing.

{
  "<type_key>": {
    "expected_type": "alb",
    "expected_arn": "arn:aws:elasticloadbalancing:us-east-2:123456789012:targetgroup/lambda-279XGJDqGZ5rsrHC2Fjr/49e9d65c45c6791a",
    "event": { ... }
  }
}

In v3, transaction names created by WrapHandle, WrapHandleFunc, nrecho-v3, nrecho-v4, nrgorilla, and nrgin now automatically include the HTTP method.

Example Change:

• Old: WebTransaction/Go/users
• New: WebTransaction/Go/GET /users

Action Required: You may need to update your New Relic alerts and dashboards to reflect these new naming patterns.