connector: add fix for long socket paths

CHANGELOG.md

@@ -7,6 +7,13 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+### Changed
+
+- A unix domain socket pathname (used in cartridge-cli to connect to instances) longer
+  than the value defined by the system resulted in a connection error.
+  It now works fine or throws a human readable error if we can't work around this
+  limitation by connecting to an instance with a relative socket path.
+
 ### Added
 
 - Tarantool benchmark tool update (select and update operations):

cli/connector/connector.go

@@ -3,6 +3,8 @@ package connector
 import (
 	"fmt"
 	"net"
+	"os"
+	"path/filepath"
 	"strings"
 	"time"
 
@@ -49,6 +51,19 @@ func Connect(connString string, opts Opts) (*Conn, error) {
 
 	connOpts := getConnOpts(connString, opts.Username, opts.Password)
 
+	if _, err := os.Stat(connOpts.Address); err == nil {
+		workDir, err := os.Getwd()
+		if err != nil {
+			return nil, err
+		}
+		os.Chdir(filepath.Dir(connOpts.Address))
+		connOpts.Address = "./" + filepath.Base(connOpts.Address)
+		defer os.Chdir(workDir)
+		if len(connOpts.Address) > 108 {
+			return nil, fmt.Errorf("Address is exceeding sun_path limit.(108 bytes)")
+		}
+	}
+
 	// connect to specified address
 	plainTextConn, err := net.Dial(connOpts.Network, connOpts.Address)
 	if err != nil {