Simple Restful API on AWS

Implement a simple Restful API on AWS using the following tech stack:

Serverless Framework ( https://serverless.com )
Go language ( https://golang.org )
AWS API Gateway
AWS Lambda
AWS DynamoDB

The API should accept the following JSON requests and produce the corresponding HTTP responses:

Request 1:

HTTP POST
URL: https://<api-gateway-url>/api/devices
Body (application/json):
{
  "id": "/devices/id1",
  "deviceModel": "/devicemodels/id1",
  "name": "Sensor",
  "note": "Testing a sensor.",
  "serial": "A020000102"
}

Response 1 - Success:

HTTP 201 Created
Body (application/json):
{
  "id": "/devices/id1",
  "deviceModel": "/devicemodels/id1",
  "name": "Sensor",
  "note": "Testing a sensor.",
  "serial": "A020000102"
}

Response 1 - Failure 1:

HTTP 400 Bad Request

If any of the payload fields are missing. Response body should have a descriptive error message for the client to be able to detect the problem.

Response 1 - Failure 2:

HTTP 500 Internal Server Error

If any exceptional situation occurs on the server side.

Request 2:

HTTP GET
URL: https://<api-gateway-url>/api/devices/{id}
Example: GET https://api123.amazonaws.com/api/devices/id1

Response 2 - Success:

HTTP 200 OK
Body (application/json):
{
  "id": "/devices/id1",
  "deviceModel": "/devicemodels/id1",
  "name": "Sensor",
  "note": "Testing a sensor.",
  "serial": "A020000102"
}

Response 2 - Failure 1:

HTTP 404 Not Found

If the request id does not exist.

Response 2 - Failure 2:

HTTP 500 Internal Server Error

If any exceptional situation occurs on the server side.

Project Structure

The project has two folders with a main.go file for each Lambda function:

CreateDevice to handle POST request
GetDevice to handle GET request

Test files and their results are in the Test Folder.

serverless.yml file is responsible to manage custom values, project packaging options, resources and permissions. The serverless will use that to deploy the project to AWS.

because of the project is developed on Windows, the commands for building project saved in Makefile file.

Deployment

Prerequisites

Before deploy with Serverless, we must install the following tools: (The environment of my development is on Windows 10)

aws cli: i use aws msi installer -> https://s3.amazonaws.com/aws-cli/AWSCLI64.msi
go: i use https://dl.google.com/go/go1.10.1.windows-amd64.msi from https://golang.org/dl/ webpage
go dep
build-lambda-zip: go get -u github.com/aws/aws-lambda-go/cmd/build-lambda-zip and go install
nodejs: i use https://nodejs.org/dist/v8.11.1/node-v8.11.1-x64.msi from https://nodejs.org/en/download/ webpage
serverless: in CMD run npm install -g serverless command

Deploy

In CMD go to folder GOPATH\src
Enter command sls create --template aws-go-dep --path MyServiceName
Create folder for each function, with main.go file in that
Create folder bin
To build functions use the following commands in each folder of lambda functions :
- %USERPROFILE%\Go\bin\dep ensure
- set GOOS=linux
- go build -o bin/CreateDevice CreateDevice/main.go
- go build -o bin/GetDevice GetDevice/main.go
- %USERPROFILE%\Go\bin\build-lambda-zip.exe -o bin/CreateDevice.zip bin/CreateDevice
- %USERPROFILE%\Go\bin\build-lambda-zip.exe -o bin/GetDevice.zip bin/GetDevice
I use build-lambda-zip to package compiled lambda functions, and then set artifact in serverless.yml to force serverless use these packages for uploading functions
The executable files will be created in bin folder, after you run.
In order to deploy, run sls deploy

After deploy successfully, two URLs will be generated. These are api URLs called API-GATEWAY-URL

Testing

For testing project, i use Postman windows software which can be download on https://www.getpostman.com/apps

Test `CreateDevice` function

in Postman enter URL https://<api-gateway-url>/api/devices and choose POST request, and in Body tab choose raw radiobutton and enter the following json request body:

{
  "id": "/devices/id1",
  "deviceModel": "/devicemodels/id1",
  "name": "Sensor",
  "note": "Testing a sensor.",
  "serial": "A020000102"
}

then click on Send button. The request will send to URL and show response in bottom section.

Test `GetDevice` function

in Postman enter URL https://<api-gateway-url>/api/devices/{id} and choose GET request (replace {id} with id1 or something else), then click on Send button. The request will send to URL and show response in bottom section.

Unit test coverage

In Test folder, go to each folder of functions and open Command Prompt and use the following commands to generate cover output and its HTML view:

go test -coverprofile=coverage.out
go tool cover -html=coverage.out -o coverage.html

Here is the results of my test:

CreateDevice:

PASS
coverage: 88.9% of statements
ok      DeviceService/Test/CreateDevice 0.108s

GetDevice:

PASS
coverage: 80.0% of statements
ok      DeviceService/Test/GetDevice    0.115s

SajjadSo/DeviceService