Overview

AWS Lambda implementation with Scala and Grpc running a simple calculator functionality. Also supports REST requests (communication with JSON over Http).

Link to Lambda clients project

Description

Uses ProtoBuffers for communication where the lambda receives request as a protobuff binary and responds the request with a protobuff.

Protcol Buffers

The following is the ProtoBuff declaration for the Input message:

message Input {

    double op1 = 1;

    double op2 = 2;

    string operator = 3;

}

Response Message:

message Response {
    string inputExpression = 1;
    double output = 2;
    string message = 3;
}

And the service:

service Calculator {
    rpc Calculate (Input) returns (Response);
}

Requests and Response

GRPC REQUEST

Http("API EndPoint").postData(protoBuffInputMessage.toByteArray)
    .header("Content-Type", "application/grpc+proto")
    .header("x-api-key", "yourApiKey").asString

Sample Request Proto received by the handler

Protobuf received
-------------------------
op1: 500.0
op2: 100.0
operator: "+"

GRPC Response

Sample Proto Response sent by the handler

Returning Protobuf
-------------------------
inputExpression: "500.0+100.0"
output: 600.0
message: "Success"

HTTP Request

curl -X GET \
  'https://a4r9djxhra.execute-api.us-east-1.amazonaws.com/default/CalculatorLambda?op1=1292922&op2=339.33&operator=%2B' \
  -H 'Postman-Token: 28fc6f99-1138-4cac-a67a-4f5bd75469f4' \
  -H 'cache-control: no-cache' \
  -H 'x-api-key: QDqkEgvLZZ2rqt5RlZ6Gx2SpOm0FsFRE5yjsByQZanan'

JSON Response

{
    "inputExpression": "1292922.0 + 339.33",
    "output": 1293261.33,
    "message": "success"
}

Steps to run

Build a fat jar using the following command :

Sbt clean assembly

This will run the tests and build a deployable jar.

Deploy the Jar on AWS Lambda. The following pictures give a snapshots.

Lambda Function Deployed

Lambda Media Type Setting For GRPC

Lambda Function Stages

CloudWatch Metrics

CloudWatch Logs