Minor fix to help testing

cmd/headscale/cli/utils.go

@@ -2,6 +2,7 @@ package cli
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"log"
@@ -20,6 +21,50 @@ type ErrorOutput struct {
 	Error string
 }
 
+func LoadConfig(path string) error {
+	viper.SetConfigName("config")
+	if path == "" {
+		viper.AddConfigPath("/etc/headscale/")
+		viper.AddConfigPath("$HOME/.headscale")
+		viper.AddConfigPath(".")
+	} else {
+		// For testing
+		viper.AddConfigPath(path)
+	}
+	viper.AutomaticEnv()
+
+	viper.SetDefault("tls_letsencrypt_cache_dir", "/var/www/.cache")
+	viper.SetDefault("tls_letsencrypt_challenge_type", "HTTP-01")
+
+	err := viper.ReadInConfig()
+	if err != nil {
+		return fmt.Errorf("Fatal error reading config file: %s \n", err)
+	}
+
+	// Collect any validation errors and return them all at once
+	var errorText string
+	if (viper.GetString("tls_letsencrypt_hostname") != "") && ((viper.GetString("tls_cert_path") != "") || (viper.GetString("tls_key_path") != "")) {
+		errorText += "Fatal config error: set either tls_letsencrypt_hostname or tls_cert_path/tls_key_path, not both\n"
+	}
+
+	if (viper.GetString("tls_letsencrypt_hostname") != "") && (viper.GetString("tls_letsencrypt_challenge_type") == "TLS-ALPN-01") && (!strings.HasSuffix(viper.GetString("listen_addr"), ":443")) {
+		errorText += "Fatal config error: when using tls_letsencrypt_hostname with TLS-ALPN-01 as challenge type, listen_addr must end in :443\n"
+	}
+
+	if (viper.GetString("tls_letsencrypt_challenge_type") != "HTTP-01") && (viper.GetString("tls_letsencrypt_challenge_type") != "TLS-ALPN-01") {
+		errorText += "Fatal config error: the only supported values for tls_letsencrypt_challenge_type are HTTP-01 and TLS-ALPN-01\n"
+	}
+
+	if !strings.HasPrefix(viper.GetString("server_url"), "http://") && !strings.HasPrefix(viper.GetString("server_url"), "https://") {
+		errorText += "Fatal config error: server_url must start with https:// or http://\n"
+	}
+	if errorText != "" {
+		return errors.New(strings.TrimSuffix(errorText, "\n"))
+	} else {
+		return nil
+	}
+}
+
 func absPath(path string) string {
 	// If a relative path is provided, prefix it with the the directory where
 	// the config file was found.