initial support for config file

go/base/context.go

@@ -15,6 +15,8 @@ import (
 
 	"github.com/github/gh-osc/go/mysql"
 	"github.com/github/gh-osc/go/sql"
+
+	"gopkg.in/gcfg.v1"
 )
 
 // RowsEstimateMethod is the type of row number estimation
@@ -41,6 +43,8 @@ type MigrationContext struct {
 	AllowedRunningOnMaster  bool
 	SwitchToRowBinlogFormat bool
 
+	ConfigFile string
+
 	ChunkSize                           int64
 	MaxLagMillisecondsThrottleThreshold int64
 	ReplictionLagQuery                  string
@@ -224,3 +228,32 @@ func (this *MigrationContext) ReadMaxLoad(maxLoadList string) error {
 	}
 	return nil
 }
+
+func (this *MigrationContext) ReadConfigFile() error {
+	if this.ConfigFile == "" {
+		return nil
+	}
+	conf := struct {
+		Client struct {
+			User     string
+			Password string
+		}
+		Osc struct {
+			Chunk_Size            int64
+			Max_Lag_Millis        int64
+			Replication_Lag_Query string
+			Max_Load              string
+		}
+	}{}
+	if err := gcfg.ReadFileInto(&conf, this.ConfigFile); err != nil {
+		return err
+	}
+	if this.InspectorConnectionConfig.User == "" {
+		this.InspectorConnectionConfig.User = conf.Client.User
+	}
+	if this.InspectorConnectionConfig.Password == "" {
+		this.InspectorConnectionConfig.User = conf.Client.Password
+	}
+
+	return nil
+}

go/cmd/gh-osc/main.go

@@ -23,6 +23,7 @@ func main() {
 	flag.IntVar(&migrationContext.InspectorConnectionConfig.Key.Port, "port", 3306, "MySQL port (preferably a replica, not the master)")
 	flag.StringVar(&migrationContext.InspectorConnectionConfig.User, "user", "root", "MySQL user")
 	flag.StringVar(&migrationContext.InspectorConnectionConfig.Password, "password", "", "MySQL password")
+	flag.StringVar(&migrationContext.ConfigFile, "conf", "", "Config file")
 
 	flag.StringVar(&migrationContext.DatabaseName, "database", "", "database name (mandatory)")
 	flag.StringVar(&migrationContext.OriginalTableName, "table", "", "table name (mandatory)")
@@ -93,6 +94,9 @@ func main() {
 	if migrationContext.QuickAndBumpySwapTables && migrationContext.TestOnReplica {
 		log.Fatalf("--quick-and-bumpy-swap-tables and --test-on-replica are mutually exclusive (the former implies migrating on master)")
 	}
+	if err := migrationContext.ReadConfigFile(); err != nil {
+		log.Fatale(err)
+	}
 	if err := migrationContext.ThrottleControlReplicaKeys.ReadCommaDelimitedList(*throttleControlReplicas); err != nil {
 		log.Fatale(err)
 	}