SignalFx Go Lambda Wrapper

SignalFx Golang Lambda Wrapper.

Usage

The SignalFx Go Lambda Wrapper is a wrapper around an AWS Lambda Go function handler, used to instrument execution of the function and send metrics to SignalFx.

Installation

To install run the command:

$ go get https://github.com/signalfx/lambda-go

Configuring the ingest endpoint

By default, this function wrapper will send to the us0 realm. If you are not in this realm you will need to set the SIGNALFX_INGEST_ENDPOINT environment variable to the correct realm ingest endpoint (https://ingest.{REALM}.signalfx.com/v2/datapoint). To determine what realm you are in, check your profile page in the SignalFx web application (click the avatar in the upper right and click My Profile).

Environment Variable

Set the SIGNALFX_AUTH_TOKEN environment variable with the appropriate SignalFx authentication token. Change the default values of the other variables accordingly if desired.

SIGNALFX_AUTH_TOKEN=<SignalFx authentication token>

SIGNALFX_INGEST_ENDPOINT=https://ingest.{REALM}.signalfx.com/v2/datapoint

SIGNALFX_SEND_TIMEOUT_SECONDS=5

Wrapping a function

The SignalFx Go Lambda Wrapper wraps the handler lambda.Handler. Use the lambda.NewHandler() function to create the handler by passing your Lambda handler function to lambda.NewHandler(). Pass the created handler to the sfxlambda.NewHandlerWrapper function to create the wrapper sfxlambda.HandlerWrapper. Finally, pass the created wrapper to the sfxlambda.Start() function. See the example below.

import (
  ...
  "github.com/aws/aws-lambda-go/lambda"
  "github.com/signalfx/lambda-go"
  ...
)
...

func handler(...) ... {
  ...  
}
...

func main() {
  ...
  handlerWrapper := sfxlambda.NewHandlerWrapper(lambda.NewHandler(handler))
  sfxlambda.Start(handlerWrapper)
  ...
}
...

Metrics and dimensions sent by the wrapper

The Lambda wrapper sends the following metrics to SignalFx:

Metric Name	Type	Description
function.invocations	Counter	Count number of Lambda invocations
function.cold_starts	Counter	Count number of cold starts
function.errors	Counter	Count number of errors from underlying Lambda handler
function.duration	Gauge	Milliseconds in execution time of underlying Lambda handler

The Lambda wrapper adds the following dimensions to all data points sent to SignalFx:

Dimension	Description
lambda_arn	ARN of the Lambda function instance
aws_region	AWS Region
aws_account_id	AWS Account ID
aws_function_name	AWS Function Name
aws_function_version	AWS Function Version
aws_function_qualifier	AWS Function Version Qualifier (version or version alias if it is not an event source mapping Lambda invocation)
event_source_mappings	AWS Function Name (if it is an event source mapping Lambda invocation)
aws_execution_env	AWS execution environment (e.g. AWS_Lambda_go1.x)
function_wrapper_version	SignalFx function wrapper qualifier (e.g. signalfx_lambda_go-0.0.1)
metric_source	The literal value of 'lambda_wrapper'

Sending custom metric in the Lambda function

Use the method sfxlambda.SendDatapoint() of HandlerWrapper to send custom metric datapoints to SignalFx from within your Lambda handler function. A sfxlambda.HandlerWrapper variable needs to be declared globally in order to be accessible from within your Lambda handler function. See example below.

import (
  ...
  "github.com/aws/aws-lambda-go/lambda"
  "github.com/signalfx/lambda-go"
  ...
)
...

var handlerWrapper sfxlambda.HandlerWrapper
...

func handler(...) ... {
  ...  
  // Custom counter metric.
  dp := datapoint.Datapoint {
      Metric: "db_calls",
      Value: datapoint.NewIntValue(1),
      MetricType: datapoint.Counter,
      Dimensions: map[string]string{"db_name":"mysql1",},
  }
  // Sending custom metric to SignalFx.
  handlerWrapper.SendDatapoints([]*datapoint.Datapoint{&dp})
  ...
}
...

func main() {
  ...
  handlerWrapper = sfxlambda.NewHandlerWrapper(lambda.NewHandler(handler))
  sfxlambda.Start(handlerWrapper)
  ...
}
...

Testing locally.

Run the command below in the lambda-go package folder

$ SIGNALFX_AUTH_TOKEN=test go test -v

License

Apache Software License v2. Copyright © 2014-2018 SignalFx