lambda-cache-example

lambda-cache-example

This project provides an example golang based lambda function which caches a key from parameter store in a local variable and refreshes it every 30 seconds. This ensures that you only hit the AWS Systems Manager Parameter Store API to refresh and not every time the lambda is triggered, therefore avoiding rate limiting your self.

example

The below example is based on the api gateway code in Announcing Go Support for AWS Lambda.

package main

import (
	"errors"
	"log"

	"github.com/aws/aws-sdk-go/aws/session"
	"github.com/wolfeidau/lambda-cache-example/pkg/ssmcache"

	"github.com/aws/aws-lambda-go/events"
	"github.com/aws/aws-lambda-go/lambda"
)

const defaultSSMKey = "/mwolfe/caching-example"

var (
	errNameNotProvided  = errors.New("no name was provided in the HTTP body")
	errConfigLoadFailed = errors.New("unable to load configuration")

	cache = ssmcache.New(session.Must(session.NewSession()))
)

// Handler is your Lambda function handler
// It uses Amazon API Gateway request/responses provided by the aws-lambda-go/events package,
// However you could use other event sources (S3, Kinesis etc), or JSON-decoded primitive types such as 'string'.
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)

	// If no name is provided in the HTTP request body, return an error
	if len(request.Body) < 1 {
		return nil, errNameNotProvided
	}

	val, err := cache.GetKey(defaultSSMKey)
	// if we failed to load configuration return an error
	if err != nil {
		return nil, errConfigLoadFailed
	}

	log.Printf("key: %s value: %s", defaultSSMKey, val)

	return &events.APIGatewayProxyResponse{
		Body:       "Hello " + request.Body,
		StatusCode: 200,
	}, nil

}

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

license

This code is released under MIT License, and is copyright Mark Wolfe.