Publish JSON endpoint to list available camera resources (HTTP 200) loaded from a YAML config file written in Golang

cameras.yml

cameras:
    Exterior (South):
        camera_id: hab_camera-1
        url : http://HOST:8091/?action=stream
        low_image : http://HOST:8091/low.png
        type : mjpeg-streamer
    Exterior IR (South):
        camera_id: hab_camera-2
        url : http://HOST:8090/?action=stream
        low_image : http://HOST:8090/low.png
        type : mjpeg-streamer
    Exterior (North):
        camera_id: hab_camera-3
        url : http://HOST:8092/?action=stream
        low_image : http://HOST:8092/low.png
        type : mjpeg-streamer
    Garden (East):
        camera_id: hab_camera-4
        url : http://HOST:8081
        low_image : http://HOST:8081/low.png
        type : motion

list_cameras.go

package main

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"net/http"
	"net/url"
	"os"
	"sync"

	"gopkg.in/yaml.v2"

	log "github.com/Sirupsen/logrus"
)

type config struct {
	Cameras map[string]camera
}

type camera struct {
	CameraId string `yaml:"camera_id" json:"camera_id"`
	Url      string `yaml:"url" json:"url"`
	Low      string `yaml:"low_image" json:"low"`
	Type     string `yaml:"type" json:"type"`
}

func testCameras(conf *config) (availableCameras *config) {

	var wg sync.WaitGroup
	wg.Add(len(conf.Cameras))

	for name, settings := range conf.Cameras {
		Url := settings.Url

		go func(name string, Url string) {

			defer wg.Done()

			// Make sure the URL is properly formatted.
			_, err := url.Parse(Url)
			if err != nil {
				log.Warn("Invalid URL: ", Url)
				delete(conf.Cameras, name)
			} else {
				response, err := http.Get(Url)
				if err != nil {
					log.Warn("Unable to get response from: ", Url)
					log.Warn(err)
					delete(conf.Cameras, name)
				} else if response.StatusCode != http.StatusOK {
					fmt.Println("Not OK")
					delete(conf.Cameras, name)
				}
			}
		}(name, Url)
	}
	wg.Wait()
	return conf
}

// Get configuration of cameras from yaml file.
func getConfig() (*config, error) {

	confFile := "/opt/chab/modules/camera/cameras.yml"

	if len(os.Args[1:]) > 0 {
		confFile = os.Args[1]
	}

	conf := &config{}

	f, err := os.Open(confFile)
	defer f.Close()
	if err != nil {
		log.Info("Could not open %s.", confFile)
		log.Info("Error: ", err)
	}

	d, err := ioutil.ReadAll(f)
	if err != nil {
		log.Info("Error reading %s.", confFile)
		log.Info("Error: ", err)
	}

	err = yaml.Unmarshal(d, conf)
	if err != nil {
		log.Info("Error: ", err)
		log.Info("Could not parse ", confFile)
	}

	return conf, err
}

func structToArray(availableCameras *config) (cameraList []byte) {

	cameraList, _ = json.Marshal(availableCameras)
	return cameraList
}

func main() {

	// Get configuration.
	conf, err := getConfig()
	if err != nil {
		log.Fatal("Failed to get configuration\n", err)
	}

	// Test cameras.
	availableCameras := testCameras(conf)

	cameraList := structToArray(availableCameras)

	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		w.Header().Set("Access-Control-Allow-Origin", "*")
		w.Write(cameraList)
	})
	http.ListenAndServe(":3000", nil)
}

TODO: Change wait group to NewTicker?