Allow configuration file to be passed as parameter

config/config.go

@@ -5,6 +5,7 @@ import (
 	"github.com/TwinProduction/gatus/core"
 	"gopkg.in/yaml.v2"
 	"io/ioutil"
+	"log"
 	"os"
 	"time"
 )
@@ -15,28 +16,44 @@ type Config struct {
 }
 
 var (
-	ErrNoServiceInConfig = errors.New("configuration file should contain at least 1 service")
-	config               *Config
+	ErrNoServiceInConfig  = errors.New("configuration file should contain at least 1 service")
+	ErrConfigFileNotFound = errors.New("configuration file not found")
+	ErrConfigNotLoaded    = errors.New("configuration is nil")
+	config                *Config
 )
 
 func Get() *Config {
 	if config == nil {
-		cfg, err := readConfigurationFile("config.yaml")
-		if err != nil {
-			if os.IsNotExist(err) {
-				cfg, err = readConfigurationFile("config.yml")
-				if err != nil {
-					panic(err)
-				}
-			} else {
-				panic(err)
-			}
-		}
-		config = cfg
+		panic(ErrConfigNotLoaded)
 	}
 	return config
 }
 
+func Load(configFile string) error {
+	log.Printf("[config][Load] Attempting to load config from configFile=%s", configFile)
+	cfg, err := readConfigurationFile(configFile)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return ErrConfigFileNotFound
+		} else {
+			return err
+		}
+	}
+	config = cfg
+	return nil
+}
+
+func LoadDefaultConfiguration() error {
+	err := Load("config.yaml")
+	if err != nil {
+		if err == ErrConfigFileNotFound {
+			return Load("config.yml")
+		}
+		return err
+	}
+	return nil
+}
+
 func readConfigurationFile(fileName string) (config *Config, err error) {
 	var bytes []byte
 	if bytes, err = ioutil.ReadFile(fileName); err == nil {

main.go

@@ -8,20 +8,36 @@ import (
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"log"
 	"net/http"
+	"os"
 )
 
 func main() {
-	go watchdog.Monitor()
+	cfg := loadConfiguration()
+	go watchdog.Monitor(cfg)
 	http.HandleFunc("/api/v1/results", serviceResultsHandler)
 	http.HandleFunc("/health", healthHandler)
 	http.Handle("/", http.FileServer(http.Dir("./static")))
-	if config.Get().Metrics {
+	if cfg.Metrics {
 		http.Handle("/metrics", promhttp.Handler())
 	}
 	log.Println("[main][main] Listening on port 8080")
 	log.Fatal(http.ListenAndServe(":8080", nil))
 }
 
+func loadConfiguration() *config.Config {
+	args := os.Args
+	var err error
+	if len(args) == 2 {
+		err = config.Load(args[1])
+	} else {
+		err = config.LoadDefaultConfiguration()
+	}
+	if err != nil {
+		panic(err)
+	}
+	return config.Get()
+}
+
 func serviceResultsHandler(writer http.ResponseWriter, _ *http.Request) {
 	serviceResults := watchdog.GetServiceResults()
 	writer.WriteHeader(http.StatusOK)

watchdog/watchdog.go

@@ -18,8 +18,8 @@ func GetServiceResults() *map[string][]*core.Result {
 	return &serviceResults
 }
 
-func Monitor() {
-	for _, service := range config.Get().Services {
+func Monitor(cfg *config.Config) {
+	for _, service := range cfg.Services {
 		go func(service *core.Service) {
 			for {
 				log.Printf("[watchdog][Monitor] Monitoring serviceName=%s", service.Name)