go-uptime-alert/main.go

package main

import (
	"encoding/json"
	"log"
	"net/http"
	"os"
	"time"
)

var (
	configFile string = os.Getenv("HOME") + "/.config/go-uptime-alert.json"
)

type Config struct {
	ServiceUrlUuids []struct {
		SiteURL             string `json:"site_url"`
		HealthChecksPingURL string `json:"hc_ping_url"`
	} `json:"service_urls_uuids"`
}

func getConfig(configFile string) (*Config, error) {
	data, err := os.ReadFile(configFile)
	if err != nil {
		return nil, err
	}

	config := &Config{}
	if err := json.Unmarshal(data, config); err != nil {
		return nil, err
	}

	return config, err
}

func checkURL(url string) (int, error) {
	resp, err := http.Get(url)
	if err != nil {
		return 0, err
	}
	defer resp.Body.Close()

	return resp.StatusCode, nil
}

func sendPingToHC(hcPingURL string) error {
	client := &http.Client{
		Timeout: 10 * time.Second,
	}

	_, err := client.Head(hcPingURL)
	if err != nil {
		return err
	}

	return nil
}

func main() {
	config, err := getConfig(configFile)
	if err != nil {
		log.Fatalln("Error getting config located at " + configFile)
	}

	for _, v := range config.ServiceUrlUuids {
		statusCode, err := checkURL(v.SiteURL)
		if err != nil {
			log.Fatalln(err)
		}

		if statusCode == http.StatusOK {
			if err := sendPingToHC(v.HealthChecksPingURL); err != nil {
				log.Printf("%s\n", err)
			} else {
				log.Printf("%s: OK\n", v.SiteURL)
			}
		} else {
			log.Printf("%s: DOWN\n", v.SiteURL)
		}
	}
}