Adding log to print all configuration flags at start of gcs fuse mount (

#1565)

* logs flags while mounting gcsfuse

* updates log message for mount flag

* fixes import lint issue

* refactors and renames toString method to support marshalling of nested struct

* refactor stringify to use json marshal

* adds method for error handling in stringify

* updates logger message for flags | remove unnecessary trim space from test

* changes stringify error log to warn log

* makes customType private

* removes extra line from TestStringifyShouldReturnEmptyStringWhenMarshalErrorsOut

* moves Stringify to util package

* adds doc for Stringify

* removes unnecessary TrimSpace

* updates Stringify docs to Go format

internal/util/util.go

@@ -15,6 +15,7 @@
 package util
 
 import (
+	"encoding/json"
 	"fmt"
 	"os"
 	"path"
@@ -80,3 +81,14 @@ func ResolveConfigFilePaths(config *config.MountConfig) (err error) {
 	}
 	return
 }
+
+// Stringify marshals an object (only exported attribute) to a JSON string. If marshalling fails, it returns an empty string.
+func Stringify(input any) string {
+	inputBytes, err := json.Marshal(input)
+
+	if err != nil {
+		logger.Warnf("Error in Stringify %v", err)
+		return ""
+	}
+	return string(inputBytes)
+}

internal/util/util_test.go

@@ -15,6 +15,7 @@
 package util
 
 import (
+	"errors"
 	"os"
 	"path/filepath"
 	"testing"
@@ -157,3 +158,52 @@ func (t *UtilTest) TestResolveConfigFilePaths() {
 	AssertEq(nil, err)
 	ExpectEq(filepath.Join(homeDir, "test.txt"), mountConfig.LogConfig.FilePath)
 }
+
+func (t *UtilTest) TestStringifyShouldReturnAllFieldsPassedInCustomObjectAsMarshalledString() {
+	sampleMap := map[string]int{
+		"1": 1,
+		"2": 2,
+		"3": 3,
+	}
+	sampleNestedValue := nestedCustomType{
+		SomeField: 10,
+		SomeOther: sampleMap,
+	}
+	customObject := &customTypeForSuccess{
+		Value:       "test_value",
+		NestedValue: sampleNestedValue,
+	}
+
+	actual := Stringify(customObject)
+
+	expected := "{\"Value\":\"test_value\",\"NestedValue\":{\"SomeField\":10,\"SomeOther\":{\"1\":1,\"2\":2,\"3\":3}}}"
+	AssertEq(expected, actual)
+}
+
+func (t *UtilTest) TestStringifyShouldReturnEmptyStringWhenMarshalErrorsOut() {
+	customInstance := customTypeForError{
+		value: "example",
+	}
+
+	actual := Stringify(customInstance)
+
+	expected := ""
+	AssertEq(expected, actual)
+}
+
+type customTypeForSuccess struct {
+	Value       string
+	NestedValue nestedCustomType
+}
+type nestedCustomType struct {
+	SomeField int
+	SomeOther map[string]int
+}
+type customTypeForError struct {
+	value string
+}
+
+// MarshalJSON returns an error to simulate a failure during JSON marshaling
+func (c customTypeForError) MarshalJSON() ([]byte, error) {
+	return nil, errors.New("intentional error during JSON marshaling")
+}

main.go

@@ -239,6 +239,8 @@ func runCLIApp(c *cli.Context) (err error) {
 	}
 
 	logger.Infof("Start gcsfuse/%s for app %q using mount point: %s\n", getVersion(), flags.AppName, mountPoint)
+	logger.Infof("GCSFuse mount command flags: %s", util.Stringify(*flags))
+	logger.Infof("GCSFuse mount config flags: %s", util.Stringify(*mountConfig))
 
 	// If we haven't been asked to run in foreground mode, we should run a daemon
 	// with the foreground flag set and wait for it to mount.

main_test.go

@@ -6,6 +6,9 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/googlecloudplatform/gcsfuse/internal/config"
+	"github.com/googlecloudplatform/gcsfuse/internal/util"
+
 	mountpkg "github.com/googlecloudplatform/gcsfuse/internal/mount"
 	. "github.com/jacobsa/ogletest"
 )
@@ -72,3 +75,43 @@ func (t *MainTest) TestGetUserAgentWhenMetadataImageTypeEnvVarSetAndAppNameNotSe
 
 	ExpectEq(expectedUserAgent, userAgent)
 }
+
+func (t *MainTest) TestStringifyShouldReturnAllFlagsPassedInMountConfigAsMarshalledString() {
+	mountConfig := &config.MountConfig{
+		WriteConfig: config.WriteConfig{
+			CreateEmptyFile: false,
+		},
+		LogConfig: config.LogConfig{
+			Severity: config.TRACE,
+			FilePath: "\"path\"to\"file\"",
+			LogRotateConfig: config.LogRotateConfig{
+				MaxFileSizeMB:   2,
+				BackupFileCount: 2,
+				Compress:        true,
+			},
+		},
+	}
+
+	actual := util.Stringify(mountConfig)
+
+	expected := "{\"CreateEmptyFile\":false,\"Severity\":\"TRACE\",\"Format\":\"\",\"FilePath\":\"\\\"path\\\"to\\\"file\\\"\",\"LogRotateConfig\":{\"MaxFileSizeMB\":2,\"BackupFileCount\":2,\"Compress\":true}}"
+	AssertEq(expected, actual)
+}
+
+func (t *MainTest) TestStringifyShouldReturnAllFlagsPassedInFlagStorageAsMarshalledString() {
+	mountOptions := map[string]string{
+		"1": "one",
+		"2": "two",
+		"3": "three",
+	}
+	flags := &flagStorage{
+		SequentialReadSizeMb: 10,
+		ClientProtocol:       mountpkg.ClientProtocol("http4"),
+		MountOptions:         mountOptions,
+	}
+
+	actual := util.Stringify(flags)
+
+	expected := "{\"AppName\":\"\",\"Foreground\":false,\"ConfigFile\":\"\",\"MountOptions\":{\"1\":\"one\",\"2\":\"two\",\"3\":\"three\"},\"DirMode\":0,\"FileMode\":0,\"Uid\":0,\"Gid\":0,\"ImplicitDirs\":false,\"OnlyDir\":\"\",\"RenameDirLimit\":0,\"CustomEndpoint\":null,\"BillingProject\":\"\",\"KeyFile\":\"\",\"TokenUrl\":\"\",\"ReuseTokenFromUrl\":false,\"EgressBandwidthLimitBytesPerSecond\":0,\"OpRateLimitHz\":0,\"SequentialReadSizeMb\":10,\"MaxRetrySleep\":0,\"StatCacheCapacity\":0,\"StatCacheTTL\":0,\"TypeCacheTTL\":0,\"HttpClientTimeout\":0,\"MaxRetryDuration\":0,\"RetryMultiplier\":0,\"LocalFileCache\":false,\"TempDir\":\"\",\"ClientProtocol\":\"http4\",\"MaxConnsPerHost\":0,\"MaxIdleConnsPerHost\":0,\"EnableNonexistentTypeCache\":false,\"StackdriverExportInterval\":0,\"OtelCollectorAddress\":\"\",\"LogFile\":\"\",\"LogFormat\":\"\",\"ExperimentalEnableJsonRead\":false,\"DebugFuseErrors\":false,\"DebugFuse\":false,\"DebugFS\":false,\"DebugGCS\":false,\"DebugHTTP\":false,\"DebugInvariants\":false,\"DebugMutex\":false}"
+	AssertEq(expected, actual)
+}