my-iot/main.go

// +build linux darwin

package main

import (
	"fmt"
	"net/http"
	"os"
	"strconv"

	"github.com/aws/aws-sdk-go/aws"
	"github.com/aws/aws-sdk-go/aws/session"
	"github.com/aws/aws-sdk-go/service/dynamodb"
	"github.com/aws/aws-sdk-go/service/dynamodb/dynamodbattribute"
	"github.com/labstack/echo"
	"github.com/labstack/echo/middleware"
)

var sess *session.Session
var err error
var svc *dynamodb.DynamoDB

func indexHandler(c echo.Context) error {
	return c.File("html/home.html")
}

func healthCheckHandler(c echo.Context) error {
	return c.JSON(http.StatusOK, `{"alive": true}`)
}

func overallHandler(c echo.Context) error {

	devices, _ := GetDevices(svc)
	var result []Item
	for _, i := range devices.Items {
		device := Device{}
		err := dynamodbattribute.UnmarshalMap(i, &device)
		if err != nil {
			return err
		}
		data, _ := device.History(svc, 1)
		one := data[0]
		one.Group = device.Group
		one.Info.Name = device.Name
		one.Info.Model = device.Model
		result = append(result, one)
	}
	return c.JSON(http.StatusOK, result)
}

// func oneDeviceHandler(w http.ResponseWriter, r *http.Request) {
func oneDeviceHandler(c echo.Context) error {
	id := c.Param("id")
	// default limit is 5
	limit, _ := strconv.ParseInt(c.QueryParam("limit"), 10, 64)
	if limit == 0 {
		limit = 5
	}
	device, err := GetDevice(svc, id)
	if err != nil {
		return c.String(http.StatusInternalServerError, "Error unmarshalling")
	}
	result, err := GetHistory(svc, id, limit)
	var ev []Item
	if err != nil {
		return c.String(http.StatusInternalServerError, "Error unmarshalling")
	}
	for _, i := range result.Items {
		item := Item{}
		err = dynamodbattribute.UnmarshalMap(i, &item)
		item.Info.Name = device.Name
		item.Info.Model = device.Model
		if err != nil {
			return c.String(http.StatusInternalServerError, "Error unmarshalling")
		}
		ev = append(ev, item)
	}
	return c.JSON(http.StatusOK, ev)
}

func main() {

	// Initialize a session in us-west-2 that the SDK will use to load
	// credentials from the shared credentials file ~/.aws/credentials.
	sess, err = session.NewSession(&aws.Config{
		Region: aws.String("ap-southeast-1")},
	)
	if err != nil {
		fmt.Println("aws error ")
		fmt.Println(err.Error())
		os.Exit(1)
	}

	// Create DynamoDB client
	svc = dynamodb.New(sess)
	e := echo.New()
	e.Use(middleware.Logger())
	e.Use(middleware.Recover())
	e.Use(middleware.CORSWithConfig(middleware.CORSConfig{
		AllowOrigins: []string{"*"},
		AllowMethods: []string{"GET", "OPTIONS"},
		AllowHeaders: []string{echo.HeaderOrigin, echo.HeaderContentType, echo.HeaderAccept},
	}))

	e.GET("/health", healthCheckHandler)
	e.GET("/id/:id", oneDeviceHandler)
	e.GET("/all", overallHandler)
	e.GET("/", indexHandler)
	e.Logger.Fatal(e.Start(":31101"))
}