Merge pull request #603 from pierresouchay/host_id_fixed_on_linux

Have a real fixed HostID on Linux

host/host_linux.go

@@ -73,7 +73,10 @@ func InfoWithContext(ctx context.Context) (*InfoStat, error) {
 	}
 
 	sysProductUUID := common.HostSys("class/dmi/id/product_uuid")
+	machineID := common.HostEtc("machine-id")
 	switch {
+	// In order to read this file, needs to be supported by kernel/arch and run as root
+	// so having fallback is important
 	case common.PathExists(sysProductUUID):
 		lines, err := common.ReadLines(sysProductUUID)
 		if err == nil && len(lines) > 0 && lines[0] != "" {
@@ -81,6 +84,16 @@ func InfoWithContext(ctx context.Context) (*InfoStat, error) {
 			break
 		}
 		fallthrough
+	// Fallback on GNU Linux systems with systemd, readable by everyone
+	case common.PathExists(machineID):
+		lines, err := common.ReadLines(machineID)
+		if err == nil && len(lines) > 0 && len(lines[0]) == 32 {
+			st := lines[0]
+			ret.HostID = fmt.Sprintf("%s-%s-%s-%s-%s", st[0:8], st[8:12], st[12:16], st[16:20], st[20:32])
+			break
+		}
+		fallthrough
+	// Not stable between reboot, but better than nothing
 	default:
 		values, err := common.DoSysctrl("kernel.random.boot_id")
 		if err == nil && len(values) == 1 && values[0] != "" {