tsmon: read hostname and region from config file

common/tsmon/target/flags.go

Index: common/tsmon/target/flags.go
diff --git a/common/tsmon/target/flags.go b/common/tsmon/target/flags.go
index b98b771fdbade92462547c0a51e1c0f1632b9593..2b89dfc468f04140a827014f7edd3604ab5e5e99 100644
--- a/common/tsmon/target/flags.go
+++ b/common/tsmon/target/flags.go
@@ -66,9 +66,6 @@ func (fl *Flags) SetDefaultsFromHostname() {
 	network := getNetwork(fl.SysInfo.Hostname)
 	hostname := fl.SysInfo.Hostname
 
-	if fl.AutoGenHostname {
-		hostname = "autogen:" + hostname
-	}
 	if fl.DeviceHostname == "" {
 		fl.DeviceHostname = hostname
 	}
@@ -84,6 +81,10 @@ func (fl *Flags) SetDefaultsFromHostname() {
 	if fl.TaskHostname == "" {
 		fl.TaskHostname = hostname
 	}
+	if fl.AutoGenHostname {
+		fl.DeviceHostname = "autogen:" + fl.DeviceHostname
+		fl.TaskHostname = "autogen:" + fl.TaskHostname
+	}
 }
 
 // Register adds tsmon target related flags to a FlagSet.