NewRelic instrumentation for AWS CDK NodeJS function

newRelic.ts

import { Stack } from "aws-cdk-lib"
import { Runtime, Architecture, ILayerVersion, LayerVersion, CfnFunction } from "aws-cdk-lib/aws-lambda"
import { NodejsFunction, NodejsFunctionProps } from "aws-cdk-lib/aws-lambda-nodejs"
import { Secret } from "aws-cdk-lib/aws-secretsmanager"
import { Construct } from "constructs"

/**
 * A NodejsFunction with New Relic instrumentation.
 * @see https://forum.newrelic.com/s/hubtopic/aAX8W0000008d3MWAQ/setting-up-new-relic-with-cdk
 */
export class NodejsFunctionWithNewRelic extends NodejsFunction {
    constructor(scope: Construct, id: string, props: NodejsFunctionProps) {

        const getLayerFromRuntimeAndArch = (
            runtime: Runtime = Runtime.NODEJS_20_X,
            arch: Architecture = Architecture.X86_64
        ): ILayerVersion => {
            const region = Stack.of(scope).region

            // See layers from here: https://layers.newrelic-external.com/
            if (runtime === Runtime.NODEJS_18_X && arch === Architecture.X86_64) {
                return LayerVersion.fromLayerVersionArn(
                    scope,
                    `${id}-newRelicLayer`,
                    `arn:aws:lambda:${region}:451483290750:layer:NewRelicNodeJS18X:88`
                )
            } else if (runtime === Runtime.NODEJS_18_X && arch === Architecture.ARM_64) {
                return LayerVersion.fromLayerVersionArn(
                    scope,
                    `${id}-newRelicLayer`,
                    `arn:aws:lambda:${region}:451483290750:layer:NewRelicNodeJS18XARM64:88`
                )
            } else if (runtime === Runtime.NODEJS_20_X && arch === Architecture.X86_64) {
                return LayerVersion.fromLayerVersionArn(
                    scope,
                    `${id}-newRelicLayer`,
                    `arn:aws:lambda:${region}:451483290750:layer:NewRelicNodeJS20X:38`
                )
            } else if (runtime === Runtime.NODEJS_20_X && arch === Architecture.ARM_64) {
                return LayerVersion.fromLayerVersionArn(
                    scope,
                    `${id}-newRelicLayer`,
                    `arn:aws:lambda:${region}:451483290750:layer:NewRelicNodeJS20XARM64:38`
                )
            }
            throw new Error("Runtime must be NODEJS_18_X|NODEJS_20_X and Architecture must be X86_64|ARM_64")
        }

        const stage = scope.node.tryGetContext("stage");
        const newRelicUKey = Secret.fromSecretNameV2(scope, `${id}-newrelic-usecret`, `${stage}/newrelic/ukey`)
        const newRelicLKey = Secret.fromSecretNameV2(scope, `${id}-newrelic-lsecret`, `${stage}/newrelic/lkey`)

        super(scope, id, {
            ...props,
            bundling: {
              sourceMap: true,
              externalModules: ['newrelic']
            },
            layers: [...(props.layers ?? []), getLayerFromRuntimeAndArch(props.runtime, props.architecture)],
            environment: {
                ...props.environment,
                NEW_RELIC_ACCOUNT_ID: newRelicUKey.secretValueFromJson("account").unsafeUnwrap(),
                NEW_RELIC_LICENSE_KEY: newRelicLKey.secretValue.unsafeUnwrap(),
                NEW_RELIC_LAMBDA_HANDLER: `index.${props.handler || 'handler'}`,

                // Enable logging
                NEW_RELIC_EXTENSION_SEND_FUNCTION_LOGS: "true",
                NEW_RELIC_EXTENSION_LOG_LEVEL: "WARN",
                NEW_RELIC_DATA_COLLECTION_TIMEOUT: "2s",

                // Performance related "suggested"
                // https://docs.newrelic.com/docs/serverless-function-monitoring/aws-lambda-monitoring/instrument-lambda-function/introduction-lambda/
                NEW_RELIC_USE_ESM: "true",
                NEW_RELIC_NATIVE_METRICS_ENABLED: "false",
                NEW_RELIC_NO_CONFIG_FILE: "true"
            },
        })

        // Override handler as per https://github.com/aws/aws-cdk/issues/16795#issuecomment-937544205
        const handler = this.node.defaultChild as CfnFunction
        handler.addOverride("Properties.Handler", "newrelic-lambda-wrapper.handler")

        // Grant read to New Relic license key secret
        newRelicLKey.grantRead(this);
    }
}