Fix the code used to get the working directory (#484)

Use os.Executable to get the directory of the exe

Author: ashvindeodhar

cns/configuration/configuration.go

@@ -8,6 +8,7 @@ import (
 	"path/filepath"
 
 	"github.com/Azure/azure-container-networking/cns/logger"
+	"github.com/Azure/azure-container-networking/common"
 )
 
 const (
@@ -46,17 +47,16 @@ func ReadConfig() (CNSConfig, error) {
 	// Check if env set for config path otherwise use default path
 	configpath, found := os.LookupEnv("CNS_CONFIGURATION_PATH")
 	if !found {
-		dir, err := filepath.Abs(filepath.Dir(os.Args[0]))
+		dir, err := common.GetExecutableDirectory()
 		if err != nil {
 			logger.Errorf("[Configuration] Failed to find exe dir:%v", err)
 			return cnsConfig, err
 		}
 
 		configpath = filepath.Join(dir, defaultConfigName)
-		//dir + string(os.PathSeparator) + defaultConfigName
 	}
 
-	logger.Printf("Config path:%s", configpath)
+	logger.Printf("[Configuration] Config path:%s", configpath)
 
 	content, err := ioutil.ReadFile(configpath)
 	if err != nil {

cns/networkcontainers/networkcontainers_windows.go

@@ -9,14 +9,14 @@ import (
 	"net"
 	"os"
 	"os/exec"
-	"path"
 	"path/filepath"
 	"strconv"
 	"strings"
 	"sync"
 
 	"github.com/Azure/azure-container-networking/cns"
 	"github.com/Azure/azure-container-networking/cns/logger"
+	"github.com/Azure/azure-container-networking/common"
 	"github.com/Azure/azure-container-networking/log"
 	"github.com/containernetworking/cni/libcni"
 )
@@ -250,12 +250,13 @@ func getAzureNetworkContainerBinaryPath() (string, error) {
 		err        error
 	)
 
-	if workingDir, err = filepath.Abs(filepath.Dir(os.Args[0])); err != nil {
+	workingDir, err = common.GetExecutableDirectory()
+	if err != nil {
 		return binaryPath,
 			fmt.Errorf("[Azure CNS] Unable to find working directory. Error: %v. Cannot continue", err)
 	}
 
-	binaryPath = path.Join(workingDir, binaryAzureNetworkContainer)
+	binaryPath = filepath.Join(workingDir, binaryAzureNetworkContainer)
 
 	if _, err = os.Stat(binaryPath); err != nil {
 		return binaryPath,

common/utils.go

@@ -14,6 +14,7 @@ import (
 	"net"
 	"net/http"
 	"os"
+	"path/filepath"
 	"strings"
 	"time"
 
@@ -323,3 +324,26 @@ func GetAzureCloud(url string) (string, error) {
 
 	return strings.TrimSpace(string(bodyBytes)), nil
 }
+
+func GetExecutableDirectory() (string, error) {
+	var (
+		dir string
+		ex  string
+		err error
+	)
+	ex, err = os.Executable()
+	if err == nil {
+		dir = filepath.Dir(ex)
+	} else {
+		var exReal string
+		// If a symlink was used to start the process, depending on the operating system,
+		// the result might be the symlink or the path it pointed to.
+		// filepath.EvalSymlinks returns stable results
+		exReal, err = filepath.EvalSymlinks(ex)
+		if err == nil {
+			dir = filepath.Dir(exReal)
+		}
+	}
+
+	return dir, err
+}