error if no prefix is configured (#1918)

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

cmd/headscale/cli/root.go

@@ -51,7 +51,7 @@ func initConfig() {
 
 	cfg, err := types.GetHeadscaleConfig()
 	if err != nil {
-		log.Fatal().Caller().Err(err).Msg("Failed to get headscale configuration")
+		log.Fatal().Err(err).Msg("Failed to read headscale configuration")
 	}
 
 	machineOutput := HasMachineOutputFlag()

hscontrol/types/config.go

@@ -650,6 +650,10 @@ func GetHeadscaleConfig() (*Config, error) {
 		return nil, err
 	}
 
+	if prefix4 == nil && prefix6 == nil {
+		return nil, fmt.Errorf("no IPv4 or IPv6 prefix configured, minimum one prefix is required")
+	}
+
 	allocStr := viper.GetString("prefixes.allocation")
 	var alloc IPAllocationStrategy
 	switch allocStr {
@@ -658,7 +662,7 @@ func GetHeadscaleConfig() (*Config, error) {
 	case string(IPAllocationStrategyRandom):
 		alloc = IPAllocationStrategyRandom
 	default:
-		log.Fatal().Msgf("config error, prefixes.allocation is set to %s, which is not a valid strategy, allowed options: %s, %s", allocStr, IPAllocationStrategySequential, IPAllocationStrategyRandom)
+		return nil, fmt.Errorf("config error, prefixes.allocation is set to %s, which is not a valid strategy, allowed options: %s, %s", allocStr, IPAllocationStrategySequential, IPAllocationStrategyRandom)
 	}
 
 	dnsConfig, baseDomain := GetDNSConfig()