AWS Lambda- ServerLess Arch

Cart Micro Service API Gateway

Lambda DynamoDB

Dhanu GuptaJanuary, 2016

AWS Lambda - Benefits

AWS Lambda – Working Model

Route 53

API Gateway

/cart

/read /create

/delete

Lambda

/CartRequestRouter/update

DynamoDB

cart

AWS Lambda - Cart Micro Service Arch

ASK

Mobile

Client

Users

Components• AWS API Gateway API Gateway helps developers deliver robust, secure, and

scalable mobile and web application back ends.

• AWS Lambda Functions Run code without thinking about servers. Pay for only the

compute time you consume.

• DynamoDB Amazon DynamoDB is a fast and flexible NoSQL database

service for all applications that need consistent, single-digit millisecond latency at any scale. It is a fully managed cloud database and supports both document and key-value store models.

• Deployment JAVA, Gradle, Jenkins Deployment

AWS DynamoDB• Create Table on DynamoDB Name : ‘cart’ Partition Key : ‘loginId’ (String) Sort key : ‘sku’ (String) Read Capacity Units : 100 Write Capacity Units : 50

# Note: If you want to read more on provisioned read/write capacities

http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/ProvisionedThroughputIntro.html

AWS Lambda• Create a new Lambda function Name : `CartRequestRouter` Handler : `com.org.cart.router.RequestRouter::lambdaHandler` Runtime Env : `Java` Memory : `1024` Timeout : `30secs` to start with Note : 1. Ensure your Lambda function is using the correct IAM role. The role

must have the ability to write/read to DynamoDB. 2. All Lambda interactions are logged in Cloudwatch logs. View the logs

for debugging.

• The Lambda function `com.aol.cart.router.RequestRouter` - ` lambdaHandler(InputStream request, OutputStream response, Context context) `

• Review & create function.

AWS API Gateway• Create a new API. Give it a name and description.

This will be our RESTful endpoint.• Create a resource. The path should be ‘/cart’ ,

for example.• We need to add one more resource as ‘/read’ under

cart as’ /cart/read’. Create a GET method with Lambda integration.

• Now let's setup the Integration Request. Cart Micro Service GET request will be of type application/json. This Integration step will map this type to a JSON object, which Lambda requires. In the Integration Requests page create a mapping template. Content-type is application/json and template:

Mapping Template{ "body" : $input.json('$'), "headers": { #foreach($header in $input.params().header.keySet()) "$header": "$util.escapeJavaScript($input.params().header.get($header))" #if($foreach.hasNext),#end #end }, "params": { #foreach($param in $input.params().path.keySet()) "$param": "$util.escapeJavaScript($util.urlDecode($input.params().path.get($param)))" #if($foreach.hasNext),#end #end }, "query": { #foreach($queryParam in $input.params().querystring.keySet()) "$queryParam": "$util.escapeJavaScript($util.urlDecode($input.params().querystring.get($queryParam)))" #if($foreach.hasNext),#end #end },"stage" : "$context.stage","requestId" : "$context.requestId","apiId" : "$context.apiId","resource-path" : "$context.resourcePath","resourceId" : "$context.resourceId","httpMethod" : "$context.httpMethod","sourceIp" : "$context.identity.sourceIp","userAgent" : "$context.identity.userAgent","accountId" : "$context.identity.accountId","apiKey" : "$context.identity.apiKey","caller" : "$context.identity.caller","user" : "$context.identity.user","userArn" : "$context.identity.userArn"}

API Gateway

API Gateway Deployment

• Let's ensure the response is correct. Cart Micro Service will respond as valid JSON.

• Lambda cannot return valid JSON Response.

• Now let's deploy this API, so we can test it! Click the Deploy API button.

Testing• We should now have a publically accessible GET

endpoint. Ex: https://xxxx.execute-api.us-west-2.amazonaws.com/prod/cart

• Make sure you add API Key to API Gateway for security purpose. Each client has to provie x-api-key:xxxxxxxx to access each REST API's.

• You can access read API as https://xxxx.execute-api.us-west-2.amazonaws.com/prod/cart/read?loginId=xxxx and response will be JSON Object like{ cart:[],

code:200, loginId:xxx}

Latency Performance Checklist

•#1 - Avoid cross-region calls: for best performance, ensure your clients, API, and backend integrations are located in the same geographical region

•#2 - Lambda functions receiving low traffic may exhibit "cold start" behavior, resulting in a fraction of requests completing with higher than usual latency. Lambda is constantly trying to improve cold start times.

•#3 - Ensure your Lambda function has appropriate memory allocation

•#4 - Use resource-based permissions whenever possible. The API Gateway console adds resource-based permissions to your Lambda function by default. If using STS credentials for your Lambda or AWS integration, please ensure STS endpoints are activated for the appropriate region for your account (See http://docs.aws.amazon.com/IAM/latest/UserGuide/id_credentials_temp_enable-regions.html)

Troubleshooting• Cloud Watch logs are your friends

References

• http://www.slideshare.net/AmazonWebServices/a-walk-in-the-cloud-with-aws-lambda-55789425

• https://aws.amazon.com/dynamodb/• https://aws.amazon.com/lambda/• https://aws.amazon.com/api-gateway/

Lambda

/CartTasks

DynamoDB

cart

AWS Lambda - Cart Tasks Scheduler

Decreased the latency viakeeping the lambda “warm start”

Learning