Add initial support for ssl encryption connections to database servers.

- Adding a command line option for users to enforce tls/ssl connections
  for the applier, inspector, and binlog reader.
- The user can optionally request server certificate verification through
  a command line option to specify the ca cert via a file path.
- Fixes an existing bug appending the timeout option to the singleton
  applier connection.

go/base/context.go

@@ -99,6 +99,8 @@ type MigrationContext struct {
 	ConfigFile        string
 	CliUser           string
 	CliPassword       string
+	UseTLS            bool
+	TlsCACertificate  string
 	CliMasterUser     string
 	CliMasterPassword string
 
@@ -695,6 +697,13 @@ func (this *MigrationContext) ApplyCredentials() {
 	}
 }
 
+func (this *MigrationContext) SetupTLS() error {
+	if this.UseTLS {
+		return this.InspectorConnectionConfig.UseTLS(this.TlsCACertificate)
+	}
+	return nil
+}
+
 // ReadConfigFile attempts to read the config file, if it exists
 func (this *MigrationContext) ReadConfigFile() error {
 	this.configMutex.Lock()

go/binlog/gomysql_reader.go

@@ -46,6 +46,7 @@ func NewGoMySQLReader(migrationContext *base.MigrationContext) (binlogReader *Go
 		Port:       uint16(binlogReader.connectionConfig.Key.Port),
 		User:       binlogReader.connectionConfig.User,
 		Password:   binlogReader.connectionConfig.Password,
+		TLSConfig:  binlogReader.connectionConfig.TLSConfig(),
 		UseDecimal: true,
 	}
 	binlogReader.binlogSyncer = replication.NewBinlogSyncer(binlogSyncerConfig)

go/cmd/gh-ost/main.go

@@ -14,6 +14,7 @@ import (
 
 	"github.com/github/gh-ost/go/base"
 	"github.com/github/gh-ost/go/logic"
+	_ "github.com/go-sql-driver/mysql"
 	"github.com/outbrain/golib/log"
 
 	"golang.org/x/crypto/ssh/terminal"
@@ -54,6 +55,9 @@ func main() {
 	flag.StringVar(&migrationContext.ConfigFile, "conf", "", "Config file")
 	askPass := flag.Bool("ask-pass", false, "prompt for MySQL password")
 
+	flag.BoolVar(&migrationContext.UseTLS, "ssl", false, "Enable SSL encrypted connections to MySQL")
+	flag.StringVar(&migrationContext.TlsCACertificate, "ssl-ca", "", "CA certificate in PEM format for TLS connections. Requires --ssl")
+
 	flag.StringVar(&migrationContext.DatabaseName, "database", "", "database name (mandatory)")
 	flag.StringVar(&migrationContext.OriginalTableName, "table", "", "table name (mandatory)")
 	flag.StringVar(&migrationContext.AlterStatement, "alter", "", "alter statement (mandatory)")
@@ -194,6 +198,9 @@ func main() {
 	if migrationContext.CliMasterPassword != "" && migrationContext.AssumeMasterHostname == "" {
 		log.Fatalf("--master-password requires --assume-master-host")
 	}
+	if migrationContext.TlsCACertificate != "" && !migrationContext.UseTLS {
+		log.Fatalf("--ssl-ca requires --ssl")
+	}
 	if *replicationLagQuery != "" {
 		log.Warningf("--replication-lag-query is deprecated")
 	}
@@ -238,6 +245,7 @@ func main() {
 	migrationContext.SetThrottleHTTP(*throttleHTTP)
 	migrationContext.SetDefaultNumRetries(*defaultRetries)
 	migrationContext.ApplyCredentials()
+	migrationContext.SetupTLS()
 	if err := migrationContext.SetCutOverLockTimeoutSeconds(*cutOverLockTimeoutSeconds); err != nil {
 		log.Errore(err)
 	}

go/logic/applier.go

@@ -73,7 +73,7 @@ func (this *Applier) InitDBConnections() (err error) {
 	if this.db, _, err = mysql.GetDB(this.migrationContext.Uuid, applierUri); err != nil {
 		return err
 	}
-	singletonApplierUri := fmt.Sprintf("%s?timeout=0", applierUri)
+	singletonApplierUri := fmt.Sprintf("%s&timeout=0", applierUri)
 	if this.singletonDB, _, err = mysql.GetDB(this.migrationContext.Uuid, singletonApplierUri); err != nil {
 		return err
 	}

go/mysql/connection.go

@@ -6,8 +6,14 @@
 package mysql
 
 import (
+	"crypto/tls"
+	"crypto/x509"
+	"errors"
 	"fmt"
+	"io/ioutil"
 	"net"
+
+	"github.com/go-sql-driver/mysql"
 )
 
 // ConnectionConfig is the minimal configuration required to connect to a MySQL server
@@ -16,6 +22,7 @@ type ConnectionConfig struct {
 	User       string
 	Password   string
 	ImpliedKey *InstanceKey
+	tlsConfig  *tls.Config
 }
 
 func NewConnectionConfig() *ConnectionConfig {
@@ -29,9 +36,10 @@ func NewConnectionConfig() *ConnectionConfig {
 // DuplicateCredentials creates a new connection config with given key and with same credentials as this config
 func (this *ConnectionConfig) DuplicateCredentials(key InstanceKey) *ConnectionConfig {
 	config := &ConnectionConfig{
-		Key:      key,
-		User:     this.User,
-		Password: this.Password,
+		Key:       key,
+		User:      this.User,
+		Password:  this.Password,
+		tlsConfig: this.tlsConfig,
 	}
 	config.ImpliedKey = &config.Key
 	return config
@@ -42,13 +50,42 @@ func (this *ConnectionConfig) Duplicate() *ConnectionConfig {
 }
 
 func (this *ConnectionConfig) String() string {
-	return fmt.Sprintf("%s, user=%s", this.Key.DisplayString(), this.User)
+	return fmt.Sprintf("%s, user=%s, usingTLS=%t", this.Key.DisplayString(), this.User, this.tlsConfig != nil)
 }
 
 func (this *ConnectionConfig) Equals(other *ConnectionConfig) bool {
 	return this.Key.Equals(&other.Key) || this.ImpliedKey.Equals(other.ImpliedKey)
 }
 
+func (this *ConnectionConfig) UseTLS(caCertificatePath string) error {
+	skipVerify := caCertificatePath == ""
+	var rootCertPool *x509.CertPool
+	if !skipVerify {
+		rootCertPool = x509.NewCertPool()
+		pem, err := ioutil.ReadFile(caCertificatePath)
+		if err != nil {
+			return err
+		}
+		if ok := rootCertPool.AppendCertsFromPEM(pem); !ok {
+			return errors.New("could not add ca certificate to cert pool")
+		}
+	}
+
+	this.tlsConfig = &tls.Config{
+		RootCAs:            rootCertPool,
+		InsecureSkipVerify: skipVerify,
+	}
+
+	if err := mysql.RegisterTLSConfig(this.Key.StringCode(), this.tlsConfig); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (this *ConnectionConfig) TLSConfig() *tls.Config {
+	return this.tlsConfig
+}
+
 func (this *ConnectionConfig) GetDBUri(databaseName string) string {
 	hostname := this.Key.Hostname
 	var ip = net.ParseIP(hostname)
@@ -57,5 +94,9 @@ func (this *ConnectionConfig) GetDBUri(databaseName string) string {
 		hostname = fmt.Sprintf("[%s]", hostname)
 	}
 	interpolateParams := true
-	return fmt.Sprintf("%s:%s@tcp(%s:%d)/%s?interpolateParams=%t&autocommit=true&charset=utf8mb4,utf8,latin1", this.User, this.Password, hostname, this.Key.Port, databaseName, interpolateParams)
+	tlsOption := "false"
+	if this.tlsConfig != nil {
+		tlsOption = this.Key.StringCode()
+	}
+	return fmt.Sprintf("%s:%s@tcp(%s:%d)/%s?interpolateParams=%t&autocommit=true&charset=utf8mb4,utf8,latin1&tls=%s", this.User, this.Password, hostname, this.Key.Port, databaseName, interpolateParams, tlsOption)
 }

go/mysql/connection_test.go

@@ -6,6 +6,7 @@
 package mysql
 
 import (
+	"crypto/tls"
 	"testing"
 
 	"github.com/outbrain/golib/log"
@@ -31,6 +32,10 @@ func TestDuplicateCredentials(t *testing.T) {
 	c.Key = InstanceKey{Hostname: "myhost", Port: 3306}
 	c.User = "gromit"
 	c.Password = "penguin"
+	c.tlsConfig = &tls.Config{
+		InsecureSkipVerify: true,
+		ServerName:         "feathers",
+	}
 
 	dup := c.DuplicateCredentials(InstanceKey{Hostname: "otherhost", Port: 3310})
 	test.S(t).ExpectEquals(dup.Key.Hostname, "otherhost")
@@ -39,6 +44,7 @@ func TestDuplicateCredentials(t *testing.T) {
 	test.S(t).ExpectEquals(dup.ImpliedKey.Port, 3310)
 	test.S(t).ExpectEquals(dup.User, "gromit")
 	test.S(t).ExpectEquals(dup.Password, "penguin")
+	test.S(t).ExpectEquals(dup.tlsConfig, c.tlsConfig)
 }
 
 func TestDuplicate(t *testing.T) {
@@ -63,5 +69,16 @@ func TestGetDBUri(t *testing.T) {
 	c.Password = "penguin"
 
 	uri := c.GetDBUri("test")
-	test.S(t).ExpectEquals(uri, "gromit:penguin@tcp(myhost:3306)/test?interpolateParams=true&autocommit=true&charset=utf8mb4,utf8,latin1")
+	test.S(t).ExpectEquals(uri, "gromit:penguin@tcp(myhost:3306)/test?interpolateParams=true&autocommit=true&charset=utf8mb4,utf8,latin1&tls=false")
+}
+
+func TestGetDBUriWithTLSSetup(t *testing.T) {
+	c := NewConnectionConfig()
+	c.Key = InstanceKey{Hostname: "myhost", Port: 3306}
+	c.User = "gromit"
+	c.Password = "penguin"
+	c.tlsConfig = &tls.Config{}
+
+	uri := c.GetDBUri("test")
+	test.S(t).ExpectEquals(uri, "gromit:penguin@tcp(myhost:3306)/test?interpolateParams=true&autocommit=true&charset=utf8mb4,utf8,latin1&tls=myhost:3306")
 }