ParseConnectionString supports Multi-Hosts

Signed-off-by: Artemiy Ryabinkov <getlag@ya.ru>

conn.go

@@ -10,6 +10,7 @@ import (
 	"fmt"
 	"io"
 	"io/ioutil"
+	"math"
 	"net"
 	"net/url"
 	"os"
@@ -947,16 +948,26 @@ func ParseURI(uri string) (ConnConfig, error) {
 		cp.Password, _ = url.User.Password()
 	}
 
-	parts := strings.SplitN(url.Host, ":", 2)
+	hasMuliHosts := strings.IndexByte(url.Host, ',') != -1
-	cp.Host = parts[0]
+	if !hasMuliHosts {
-	if len(parts) == 2 {
+		parts := strings.SplitN(url.Host, ":", 2)
-		p, err := strconv.ParseUint(parts[1], 10, 16)
+		cp.Host = parts[0]
-		if err != nil {
+		if len(parts) == 2 {
-			return cp, err
+			p, err := strconv.ParseUint(parts[1], 10, 16)
+			if err != nil {
+				return cp, err
+			}
+			cp.Port = uint16(p)
 		}
-		cp.Port = uint16(p)
+	} else {
+		cp.Host = url.Host
 	}
+
 	cp.Database = strings.TrimLeft(url.Path, "/")
+	cp.TargetSessionAttrs = TargetSessionType(url.Query().Get("target_session_attrs"))
+	if err := cp.TargetSessionAttrs.isValid(); err != nil {
+		return cp, err
+	}
 
 	if pgtimeout := url.Query().Get("connect_timeout"); pgtimeout != "" {
 		timeout, err := strconv.ParseInt(pgtimeout, 10, 64)
@@ -980,11 +991,12 @@ func ParseURI(uri string) (ConnConfig, error) {
 	}
 
 	ignoreKeys := map[string]struct{}{
-		"connect_timeout": {},
+		"connect_timeout":      {},
-		"sslcert":         {},
+		"sslcert":              {},
-		"sslkey":          {},
+		"sslkey":               {},
-		"sslmode":         {},
+		"sslmode":              {},
-		"sslrootcert":     {},
+		"sslrootcert":          {},
+		"target_session_attrs": {},
 	}
 
 	cp.RuntimeParams = make(map[string]string)
@@ -1029,6 +1041,7 @@ func ParseDSN(s string) (ConnConfig, error) {
 
 	cp.RuntimeParams = make(map[string]string)
 
+	var hostval, portval string
 	for _, b := range m {
 		switch b[1] {
 		case "user":
@@ -1036,13 +1049,9 @@ func ParseDSN(s string) (ConnConfig, error) {
 		case "password":
 			cp.Password = b[2]
 		case "host":
-			cp.Host = b[2]
+			hostval = b[2]
 		case "port":
-			p, err := strconv.ParseUint(b[2], 10, 16)
+			portval = b[2]
-			if err != nil {
-				return cp, err
-			}
-			cp.Port = uint16(p)
 		case "dbname":
 			cp.Database = b[2]
 		case "sslmode":
@@ -1061,26 +1070,94 @@ func ParseDSN(s string) (ConnConfig, error) {
 			d := defaultDialer()
 			d.Timeout = time.Duration(timeout) * time.Second
 			cp.Dial = d.Dial
+		case "target_session_attrs":
+			cp.TargetSessionAttrs = TargetSessionType(b[2])
+			if err := cp.TargetSessionAttrs.isValid(); err != nil {
+				return cp, err
+			}
 		default:
 			cp.RuntimeParams[b[1]] = b[2]
 		}
 	}
 
-	err := configTLS(tlsArgs, &cp)
+	host, port, err := parseHostPortDSN(hostval, portval)
 	if err != nil {
 		return cp, err
 	}
+
+	cp.Host, cp.Port = host, port
+
+	err = configTLS(tlsArgs, &cp)
+	if err != nil {
+		return cp, err
+	}
+
 	if cp.Password == "" {
 		pgpass(&cp)
 	}
+
 	return cp, nil
 }
 
-// ParseConnectionString parses either a URI or a DSN connection string.
+func parseHostPortDSN(hostval, portval string) (host string, port uint16, err error) {
-// see ParseURI and ParseDSN for details.
+	if portval == "" {
+		return hostval, 0, nil
+	}
+
+	hosts := strings.Split(hostval, ",")
+	ports := strings.Split(portval, ",")
+
+	if len(ports) == 1 {
+		port, err := parsePort(portval)
+		if err != nil {
+			return "", 0, errors.Errorf("invalid port: %v", err)
+		}
+
+		return hostval, port, nil
+	}
+
+	if len(hosts) != len(ports) {
+		return "", 0, errors.New("the number of hosts and ports must be the same")
+	}
+
+	hostports := make([]string, len(hosts))
+	for i, host := range hosts {
+		hostports[i] = host + ":" + ports[i]
+	}
+
+	return strings.Join(hostports, ","), 0, nil
+}
+
+func parsePort(s string) (uint16, error) {
+	port, err := strconv.ParseUint(s, 10, 16)
+	if err != nil {
+		return 0, err
+	}
+	if port < 1 || port > math.MaxUint16 {
+		return 0, errors.New("outside range")
+	}
+	return uint16(port), nil
+}
+
+// ParseConnectionString parses either a URI or a DSN connection string and builds ConnConfig.
+//
+//   # Example DSN
+//   user=jack password=secret host=pg.example.com port=5432 dbname=mydb sslmode=verify-ca
+//
+//   # Example URL
+//   postgres://jack:secret@pg.example.com:5432/mydb?sslmode=verify-ca
+//
+// ParseConnectionString supports specifying multiple hosts in similar manner to libpq.
+// Host and port may include comma separated values that will be tried in order.
+// This can be used as part of a high availability system.
+// See https://www.postgresql.org/docs/11/libpq-connect.html#LIBPQ-MULTIPLE-HOSTS for more information.
+//
+//   # Example URL
+//   postgres://jack:secret@foo.example.com:5432,bar.example.com:5432/mydb
+//
+//   # Example DSN
+//   user=jack password=secret host=host1,host2,host3 port=5432,5433,5434 dbname=mydb sslmode=verify-ca
 func ParseConnectionString(s string) (ConnConfig, error) {
-	// TODO: Multiple Hosts support
-	// @see: https://www.postgresql.org/docs/10/libpq-connect.html#LIBPQ-MULTIPLE-HOSTS
 	if u, err := url.Parse(s); err == nil && u.Scheme != "" {
 		return ParseURI(s)
 	}

conn_test.go

@@ -622,6 +622,38 @@ func TestParseURI(t *testing.T) {
 				RuntimeParams:     map[string]string{},
 			},
 		},
+		{
+			url: "postgres://jack:secret@foo.example.com:5432,bar.example.com:5432/mydb",
+			connParams: pgx.ConnConfig{
+				User:     "jack",
+				Password: "secret",
+				Host:     "foo.example.com:5432,bar.example.com:5432",
+				Database: "mydb",
+				TLSConfig: &tls.Config{
+					InsecureSkipVerify: true,
+				},
+				UseFallbackTLS:    true,
+				FallbackTLSConfig: nil,
+				RuntimeParams:     map[string]string{},
+			},
+		},
+		{
+			url: "postgres://jack@localhost,10.10.20.30/mydb?application_name=pgxtest&target_session_attrs=read-write",
+			connParams: pgx.ConnConfig{
+				User:     "jack",
+				Host:     "localhost,10.10.20.30",
+				Database: "mydb",
+				TLSConfig: &tls.Config{
+					InsecureSkipVerify: true,
+				},
+				UseFallbackTLS:    true,
+				FallbackTLSConfig: nil,
+				RuntimeParams: map[string]string{
+					"application_name": "pgxtest",
+				},
+				TargetSessionAttrs: pgx.ReadWriteTargetSession,
+			},
+		},
 	}
 
 	for i, tt := range tests {
@@ -748,6 +780,50 @@ func TestParseDSN(t *testing.T) {
 				RuntimeParams:     map[string]string{},
 			},
 		},
+		{
+			url: "user=jack host=localhost1,localhost2 dbname=mydb connect_timeout=10",
+			connParams: pgx.ConnConfig{
+				User:     "jack",
+				Host:     "localhost1,localhost2",
+				Database: "mydb",
+				TLSConfig: &tls.Config{
+					InsecureSkipVerify: true,
+				},
+				Dial:              (&net.Dialer{Timeout: 10 * time.Second, KeepAlive: 5 * time.Minute}).Dial,
+				UseFallbackTLS:    true,
+				FallbackTLSConfig: nil,
+				RuntimeParams:     map[string]string{},
+			},
+		},
+		{
+			url: "user=jack host=100.200.220.50,localhost43 port=5432,5433 dbname=mydb",
+			connParams: pgx.ConnConfig{
+				User:     "jack",
+				Host:     "100.200.220.50:5432,localhost43:5433",
+				Database: "mydb",
+				TLSConfig: &tls.Config{
+					InsecureSkipVerify: true,
+				},
+				UseFallbackTLS:    true,
+				FallbackTLSConfig: nil,
+				RuntimeParams:     map[string]string{},
+			},
+		},
+		{
+			url: "user=jack host=localhost dbname=mydb target_session_attrs=read-write",
+			connParams: pgx.ConnConfig{
+				User:     "jack",
+				Host:     "localhost",
+				Database: "mydb",
+				TLSConfig: &tls.Config{
+					InsecureSkipVerify: true,
+				},
+				UseFallbackTLS:    true,
+				FallbackTLSConfig: nil,
+				RuntimeParams:     map[string]string{},
+				TargetSessionAttrs: pgx.ReadWriteTargetSession,
+			},
+		},
 	}
 
 	for i, tt := range tests {