Get brian lambda AWS go

main.go

package main

import (
	"errors"
	"log"
	"math/rand"
	"net/http"
	"strconv"
	"time"

	"github.com/aws/aws-lambda-go/events"
	"github.com/aws/aws-lambda-go/lambda"
	"github.com/aws/aws-sdk-go/aws"
	"github.com/aws/aws-sdk-go/aws/session"
	"github.com/aws/aws-sdk-go/service/s3"
)

const (
	BrianBucket = "brian-bucket-205477"
)

var (
	ErrBrian = errors.New("could not compute brian")
)

// Handler is the Lambda function handler
// It uses Amazon API Gateway request/responses provided by the aws-lambda-go/events package,
func Handler(request events.APIGatewayProxyRequest) (events.APIGatewayProxyResponse, error) {

	// stdout and stderr are sent to AWS CloudWatch Logs
	log.Printf("Processing Lambda request %s\n", request.RequestContext.RequestID)
	log.Printf(request.Path)

	if request.HTTPMethod == http.MethodGet {
		url, err := fetchBrian()
		if err != nil {
			log.Printf("couldn't get a brian %s", err)
			return events.APIGatewayProxyResponse{}, ErrBrian
		}
		return events.APIGatewayProxyResponse{Body: "Here's a signed Brian: " + url, StatusCode: 200}, nil
	}
	return events.APIGatewayProxyResponse{}, ErrBrian
}

func fetchBrian() (string, error) {
	//Do some S3 magic here to generate a URL
	//Cache some of these
	sess, err := session.NewSession(&aws.Config{
		Region: aws.String("eu-west-1")})
	if err != nil {
		log.Fatal("couldn't create session!")
	}

	brianNum := "brian" + strconv.Itoa(int(rand.Int31n(94))+1) + ".png"

	svc := s3.New(sess)
	obj, _ := svc.GetObjectRequest(&s3.GetObjectInput{
		Bucket: aws.String(BrianBucket),
		Key:    aws.String(brianNum)})
	if err != nil {
		log.Println("couldn't get s3 object")
		return "", err
	}
	urlstr, err := obj.Presign(1 * time.Minute)
	if err != nil {
		log.Println("Failed to sign request", err)
		return "", err
	}
	return urlstr, nil
}

func main() {
	lambda.Start(Handler)
}