Widgets API

Deploys a Golang API to manage Widgets using Lambda, DynamoDB and API Gateway.

Prerequisites

Setting up the environment

The initial idea was to use Terraform to do the deploy of API, but how I'm learning about it, I don't had time do to that. Sorry :/ But if you follow all the steps below the API will work perfectly.

But for now you can follow the steps below:

1 - Creating the Lambda function

Go to the Lambda service;
Click in the Create a function button, give your function a name (WidgetsAPI)
Choose Go as the Runtime;
Create a new role with permission to manage your application: choose Create new role from template, give your role a name (widgets-api-role) and then choose Simple Microservice permissions as the Policy template;
In the new page, you need to put these Environment variables, then click on save button at the top of the page:
- REGION_AWS (Ex: us-east-1)
- WIDGETS_TABLE (Ex: widgets)
- JWT_TOKEN (Ex: secret)

2 - Creating a new DynamoDB table

Go to the [DynamoDB service] (https://console.aws.amazon.com/dynamodb/home);
You need to click in the Create table button to create the two tables that you put in the Environment variables of lambda configuration, and put id as our primary key.

3 - Creating a new API Gateway

Go to the API Gateway service and click in the Get Started button (If you already have a API Gateway you click in the button + Create API);
Choose New API in the radio buttons and give you API a name (WidgetsAPI), then click in the button Create API.

4 - Create Widgets Resources (Inside API Gateway)

In the Resources page, click in the resource that was already created for you (/), click in Actions and select Create Resource.
Give your resource a name (Widgets) and specify it's path name (widgets).
Now click in your /widgets resource and repeat the process: click in the Actions button, give it a name (SingleWidget) and a path name ({id}, it's only these part, because it's a child of /widgets, so our resource path is going to be /widgets/{id}).
Now, let's create the methods: click in the /widgets resource, click in the Actions button, select Create Method and choose GET. in the method setup, choose Lambda Function as the Integration type, check the Use Lambda Proxy integration checkbox, choose the Region where your Lambda is and enter its name (WidgetsAPI). Repeat this process to create a POST method to /widgets and (GET, PUT) methods to /widgets/{id}.

Deploying to AWS

To deploy our application we need to follow some steps. First, we're going to send our application to our Lambda function:

Download the project dependencies

Install Golang Dep

Run the code below:

# Download all project dependencies
$ dep ensure

Compile your code using:

# Compile the code to linux OS
$ GOOS=linux go build -o widgets-api main.go

# Compress your executable into a zip file
$ zip widgets-api.zip widgets-api

Go to your Lambda function at your AWS Console.
In the Function code section, upload your .zip file and change your Handler to widgets-api.
Click in the Save button at the top of the page.

To all of our tests you need to put the Authorization header before do the test (Authorization:Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.e30.t-IDcSemACt8x4iTMCda8Yhe3iZaWbvV5XKSTbuAn0M)

To create some widget in the database you can select the POST /widgets resource, click in the TEST icon and fill the Request body with:

{
    "name": "My Widget",
    "color": "purple",
    "price": "23,49",
    "melts": true,
    "inventory": "50"
}

Execute the test and you may receive the Created response. Now if you do the request to GET widgets you'll receive a list with these widget.

To edit a widget you can select PUT {id} resource, click in the TEST icon and fill these fields:

Request body:

{
    "name": "My Widget",
    "color": "purple",
    "price": "23,49",
    "melts": true,
    "inventory": "50"
}

{id} with the ID of the widget that you receive in GET /widgets resource:
```
cfc3a148-ab5e-4b51-a5bf-a69f125fbdfc
```

After the request, the widget update will be returned in the response.

If all tests are ok you can deploy the API. Click in the Actions button, select Deploy API, create a new stage (EX: production) and you'll get the Invoke URL that you'll use to call the API. Now you can use <invoke-url>/<endpoint> to call the API from all places.

Documentation

To see the API documentation you need to follow these steps:

Get Swagger client

$ go get github.com/yvasiyarov/swagger

Run Swagger

swagger -apiPackage="github.com/henriqueholanda/widgets-api" -mainApiFile="widgets-api.go" -format=markdown -output=./doc.md