epsagon-go

Epsagon Instrumentation for Go

Installing

go get github.com/epsagon/epsagon-go

Or using dep:

dep ensure -add github.com/epsagon/epsagon-go

Usage

To wrap a lambda handler

package main

import (
	"github.com/aws/aws-lambda-go/events"
	"github.com/aws/aws-lambda-go/lambda"
	"github.com/epsagon/epsagon-go/epsagon"
	"log"
)

func myHandler(request events.APIGatewayProxyRequest) (events.APIGatewayProxyResponse, error) {
	log.Println("In myHandler, received body: ", request.Body)
	return events.APIGatewayProxyResponse{Body: request.Body, StatusCode: 200}, nil
}

func main() {
	log.Println("enter main")
	lambda.Start(epsagon.WrapLambdaHandler(
        &epsagon.Config{ApplicationName: "APPLICATION-NAME"},
        myHandler))
}

epsagon.WrapLambdaHandler will wrap your handler with code that will start a tracer that will wait for events and will send them to the collector when the lambda finishes

Wrapping other libraries

aws-sdk-go

Wrapping of aws-sdk-go is done through the Session object that has to be created to communicate with AWS:

import (
...
	"github.com/epsagon/epsagon-go/wrappers/aws/aws-sdk-go/aws"
)
    ...
	sess := epsagonawswrapper.WrapSession(session.Must(session.NewSession()))
	svcSQS := sqs.New(sess)

net/http

Wrapping http requests using the net/http library can be done by wrapping the client:

import (
	"github.com/epsagon/epsagon-go/wrappers/net/http"
...
	client := epsagonhttp.Wrap(http.Client{})
	resp, err := client.Get(anyurl)

Configuration

The epsagon.Config structure that is sent to WraphLambdaHandler has some fields to customize epsagons behaviour:

• MetadataOnly: Boolean flag to make sure to only send metadata information and not the data itself
• Debug: Will print debug information form epsagon
• CollectorURL: Set the collector's address instead of getting it from EPSAGON_COLLECTOR_URL or using epsagon's default in the same aws region
• Token: Your epsagon token (The default is to attempt to read this from EPSAGON_TOKEN environment variable)