Merge pull request #1 from cjessett/flags

Flags

Author: cjessett

README.md

@@ -4,16 +4,6 @@ This script reads an MCP9808 temperature sensor from a Raspberry Pi and updates
 
 ## Prerequisites
 
-Create a `.env` file with the following:
-```
-THING_NAME=<Thing name>
-ENDPOINT=<Thing endpoint>
-PRIVATE_KEY_PATH=<path to private key>
-CERT_PATH=<path to cert>
-ROOT_CA_PATH=<path to root ca>
-LOG_FILE_PATH=<path to log file>
-```
-
 ### Wire up the MCP9808
 ![fritzing](rpi-temp.jpg)
 
@@ -26,5 +16,37 @@ make
 
 ## Execute the script
 ```
-./mcp9808-thing
+./mcp9808-thing -thing=<thing_name> -endpoint=<endpoint> -privatekey=<key_path> -cert=<cert_path> -rootca=<rootCA_path> -logfile=<log_path>
+```
+
+### Create a start script
+
+Create a `.env` file with the following:
+```
+export THING_NAME=<Thing name>
+export ENDPOINT=<Thing endpoint>
+export PRIVATE_KEY_PATH=<path to private key>
+export CERT_PATH=<path to cert>
+export ROOT_CA_PATH=<path to root ca>
+export LOG_FILE_PATH=<path to log file>
+```
+
+Create a `start` script to convert env variables to flags and execute the binary
+```
+#!/bin/bash
+
+source .env
+
+./mcp9808-thing \
+  -thing=${THING_NAME} \
+  -endpoint=${ENDPOINT} \
+  -privatekey=${PRIVATE_KEY_PATH} \
+  -cert=${CERT_PATH} \
+  -rootca=${ROOT_CA_PATH} \
+  -logfile=${LOG_FILE_PATH}
+```
+
+Execute the script
+```
+./start
 ```

main.go

@@ -2,46 +2,50 @@ package main
 
 import (
 	"encoding/json"
+	"flag"
 	"fmt"
 	"io"
-	"log"
 	"os"
 
-	"github.com/joho/godotenv"
 	"github.com/kuzemkon/aws-iot-device-sdk-go/device"
+	"github.com/sirupsen/logrus"
 	"periph.io/x/periph/conn/i2c/i2creg"
 	"periph.io/x/periph/experimental/devices/mcp9808"
 	"periph.io/x/periph/host"
 )
 
-type Shadow struct {
-	State struct {
-		Reported struct {
-			Temp int `json:"temp"`
-		} `json:"reported"`
-	} `json:"state"`
-	Version int
-}
+var thingName string
+var endpoint string
+var privateKey string
+var cert string
+var rootCA string
+var logFile string
+var log = logrus.New()
+
+func init() {
+	flag.StringVar(&thingName, "thing", "", "Set this to the AWS IoT thing name")
+	flag.StringVar(&endpoint, "endpoint", "", "Set this to the AWS IoT endpoint")
+	flag.StringVar(&privateKey, "privatekey", "", "This must be a full path to the AWS IoT thing private key .pem.key file")
+	flag.StringVar(&cert, "cert", "", "This must be a full path to the AWS IoT thing cert .pem.crt file")
+	flag.StringVar(&rootCA, "rootca", "", "This must be a full path to the AWS IoT thing root-CA .crt file")
+	flag.StringVar(&logFile, "logfile", "", "Set this to the full path for the log file")
+	flag.Parse()
+
+	if thingName == "" || endpoint == "" || privateKey == "" || cert == "" || rootCA == "" || logFile == "" {
+		flag.PrintDefaults()
+		log.Panic("missing required flag")
+	}
 
-func initEnv() error {
-	home, err := os.UserHomeDir()
+	// Initilize logging
+	file, err := os.OpenFile(logFile, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
 	if err != nil {
-		return err
+		log.Info("error opening file: %v", err)
 	}
-	err = godotenv.Load(fmt.Sprintf("%s/.env", home))
-	return err
-}
 
-func initThing() (*device.Thing, error) {
-	thingName := device.ThingName(os.Getenv("THING_NAME"))
-	endpoint := os.Getenv("ENDPOINT")
-	keyPair := device.KeyPair{
-		PrivateKeyPath:    os.Getenv("PRIVATE_KEY_PATH"),
-		CertificatePath:   os.Getenv("CERT_PATH"),
-		CACertificatePath: os.Getenv("ROOT_CA_PATH"),
-	}
+	mw := io.MultiWriter(os.Stdout, file)
 
-	return device.NewThing(keyPair, endpoint, thingName)
+	log.SetFormatter(&logrus.JSONFormatter{})
+	log.SetOutput(mw)
 }
 
 func readTemp() int {
@@ -73,32 +77,32 @@ func readTemp() int {
 	return int(measurement.Fahrenheit())
 }
 
-func main() {
-	err := initEnv()
-	if err != nil {
-		panic(err)
-	}
+type Shadow struct {
+	State struct {
+		Reported struct {
+			Temp int `json:"temp"`
+		} `json:"reported"`
+	} `json:"state"`
+	Version int
+}
 
-	logPath := os.Getenv("LOG_FILE_PATH")
-	f, err := os.OpenFile(logPath, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
-	if err != nil {
-		log.Fatalf("error opening file: %v", err)
+func main() {
+	// Initilize a new Thing
+	keyPair := device.KeyPair{
+		PrivateKeyPath:    privateKey,
+		CertificatePath:   cert,
+		CACertificatePath: rootCA,
 	}
-	defer f.Close()
 
-	mw := io.MultiWriter(os.Stdout, f)
-	log.SetOutput(mw)
-
-	// Initilize a new Thing
-	thing, err := initThing()
+	thing, err := device.NewThing(keyPair, endpoint, device.ThingName(thingName))
 	if err != nil {
-		panic(err)
+		log.Panic(err)
 	}
 
 	// Subscribe to shadow
 	shadowChan, err := thing.SubscribeForThingShadowChanges()
 	if err != nil {
-		panic(err)
+		log.Panic(err)
 	}
 
 	// Read temperature from sensor
@@ -108,20 +112,23 @@ func main() {
 	// Update thing shadow
 	err = thing.UpdateThingShadow(device.Shadow(shadow))
 	if err != nil {
-		panic(err)
+		log.Panic(err)
 	}
 
 	updatedShadow, ok := <-shadowChan
 	if !ok {
-		panic("Failed to read from shadow channel")
+		log.Panic("Failed to read from shadow channel")
 	}
 
 	unmarshaledUpdatedShadow := &Shadow{}
 
 	err = json.Unmarshal(updatedShadow, unmarshaledUpdatedShadow)
 	if err != nil {
-		panic(err)
+		log.Panic(err)
 	}
 
-	log.Printf("Temp: %v Version: %v", unmarshaledUpdatedShadow.State.Reported.Temp, unmarshaledUpdatedShadow.Version)
+	log.WithFields(logrus.Fields{
+		"temperature": unmarshaledUpdatedShadow.State.Reported.Temp,
+		"version":     unmarshaledUpdatedShadow.Version,
+	}).Info("Updated Shadow")
 }