rbd: provide alternatives to preserve the ceph log files

Currently, we delete the ceph client log file on unmap/detach.

This patch provides additional alternatives for users who would like to
persist the log files.

Strategies:
-----------
`remove`: delete log file on unmap/detach
`compress`: compress the log file to gzip on unmap/detach
`preserve`: preserve the log file in text format

Note that the default strategy will be remove on unmap, and these options
can be tweaked from the storage class

Compression size details example:

On Map: (with debug-rbd=20)
---------
$ ls -lh
-rw-r--r-- 1 root root 526K Sep  1 18:15
rbd-nbd-0001-0024-fed5480a-f00f-417a-a51d-31d8a8144c03-0000000000000003-d2e89c87-0b4d-11ec-8ea6-160f128e682d.log

On unmap:
---------
$ ls -lh
-rw-r--r-- 1 root root  33K Sep  1 18:15
rbd-nbd-0001-0024-fed5480a-f00f-417a-a51d-31d8a8144c03-0000000000000003-d2e89c87-0b4d-11ec-8ea6-160f128e682d.gz

Signed-off-by: Prasanna Kumar Kalever <prasanna.kalever@redhat.com>

internal/rbd/nodeserver.go

@@ -225,6 +225,10 @@ func populateRbdVol(
 	if rv.LogDir == "" {
 		rv.LogDir = defaultLogDir
 	}
+	rv.LogStrategy = req.GetVolumeContext()["cephLogStrategy"]
+	if rv.LogStrategy == "" {
+		rv.LogStrategy = defaultLogStrategy
+	}
 
 	return rv, err
 }
@@ -846,6 +850,7 @@ func (ns *NodeServer) NodeUnstageVolume(
 		volumeID:          req.GetVolumeId(),
 		unmapOptions:      imgInfo.UnmapOptions,
 		logDir:            imgInfo.LogDir,
+		logStrategy:       imgInfo.LogStrategy,
 	}
 	if err = detachRBDImageOrDeviceSpec(ctx, &dArgs); err != nil {
 		log.ErrorLog(

internal/rbd/rbd_attach.go

@@ -102,6 +102,7 @@ type detachRBDImageArgs struct {
 	volumeID          string
 	unmapOptions      string
 	logDir            string
+	logStrategy       string
 }
 
 // rbdGetDeviceList queries rbd about mapped devices and returns a list of rbdDeviceInfo
@@ -383,6 +384,7 @@ func createPath(ctx context.Context, volOpt *rbdVolume, device string, cr *util.
 				volumeID:          volOpt.VolID,
 				unmapOptions:      volOpt.UnmapOptions,
 				logDir:            volOpt.LogDir,
+				logStrategy:       volOpt.LogStrategy,
 			}
 			detErr := detachRBDImageOrDeviceSpec(ctx, &dArgs)
 			if detErr != nil {
@@ -490,10 +492,7 @@ func detachRBDImageOrDeviceSpec(
 	}
 	if dArgs.isNbd && dArgs.logDir != "" {
 		logFile := getCephClientLogFileName(dArgs.volumeID, dArgs.logDir, "rbd-nbd")
-		if err = os.Remove(logFile); err != nil {
-			log.WarningLog(ctx, "failed to remove logfile: %s, error: %v",
-				logFile, err)
-		}
+		go strategicActionOnLogFile(ctx, dArgs.logStrategy, logFile)
 	}
 
 	return nil

internal/rbd/rbd_util.go

@@ -53,6 +53,7 @@ const (
 	rbdDefaultMounter        = "rbd"
 	rbdNbdMounter            = "rbd-nbd"
 	defaultLogDir            = "/var/log/ceph"
+	defaultLogStrategy       = "remove" // supports remove, compress and preserve
 
 	// Output strings returned during invocation of "ceph rbd task add remove <imagespec>" when
 	// command is not supported by ceph manager. Used to check errors and recover when the command
@@ -140,6 +141,7 @@ type rbdVolume struct {
 	MapOptions         string
 	UnmapOptions       string
 	LogDir             string
+	LogStrategy        string
 	VolName            string `json:"volName"`
 	MonValueFromSecret string `json:"monValueFromSecret"`
 	VolSize            int64  `json:"volSize"`
@@ -1515,8 +1517,9 @@ type rbdImageMetadataStash struct {
 	UnmapOptions   string `json:"unmapOptions"`
 	NbdAccess      bool   `json:"accessType"`
 	Encrypted      bool   `json:"encrypted"`
-	DevicePath     string `json:"device"` // holds NBD device path for now
-	LogDir         string `json:"logDir"` // holds the client log path
+	DevicePath     string `json:"device"`          // holds NBD device path for now
+	LogDir         string `json:"logDir"`          // holds the client log path
+	LogStrategy    string `json:"logFileStrategy"` // ceph client log strategy
 }
 
 // file name in which image metadata is stashed.
@@ -1548,6 +1551,7 @@ func stashRBDImageMetadata(volOptions *rbdVolume, metaDataPath string) error {
 	if volOptions.Mounter == rbdTonbd && hasNBD {
 		imgMeta.NbdAccess = true
 		imgMeta.LogDir = volOptions.LogDir
+		imgMeta.LogStrategy = volOptions.LogStrategy
 	}
 
 	encodedBytes, err := json.Marshal(imgMeta)
@@ -2021,3 +2025,23 @@ func CheckSliceContains(options []string, opt string) bool {
 
 	return false
 }
+
+// strategicActionOnLogFile act on log file based on cephLogStrategy.
+func strategicActionOnLogFile(ctx context.Context, logStrategy, logFile string) {
+	var err error
+
+	switch strings.ToLower(logStrategy) {
+	case "compress":
+		if err = log.GzipLogFile(logFile); err != nil {
+			log.ErrorLog(ctx, "failed to compress logfile %q: %v", logFile, err)
+		}
+	case "remove":
+		if err = os.Remove(logFile); err != nil {
+			log.ErrorLog(ctx, "failed to remove logfile %q: %v", logFile, err)
+		}
+	case "preserve":
+		// do nothing
+	default:
+		log.ErrorLog(ctx, "unknown cephLogStrategy option %q: hint: 'remove'|'compress'|'preserve'", logStrategy)
+	}
+}

internal/rbd/rbd_util_test.go

@@ -17,6 +17,9 @@ limitations under the License.
 package rbd
 
 import (
+	"context"
+	"io/ioutil"
+	"os"
 	"strings"
 	"testing"
 
@@ -208,3 +211,75 @@ func TestGetCephClientLogFileName(t *testing.T) {
 		})
 	}
 }
+
+func TestStrategicActionOnLogFile(t *testing.T) {
+	t.Parallel()
+	ctx := context.TODO()
+	tmpDir := t.TempDir()
+
+	var logFile [3]string
+	for i := 0; i < 3; i++ {
+		f, err := ioutil.TempFile(tmpDir, "rbd-*.log")
+		if err != nil {
+			t.Errorf("creating tempfile failed: %v", err)
+		}
+		logFile[i] = f.Name()
+	}
+
+	type args struct {
+		logStrategy string
+		logFile     string
+	}
+	tests := []struct {
+		name string
+		args args
+	}{
+		{
+			name: "test for compress",
+			args: args{
+				logStrategy: "compress",
+				logFile:     logFile[0],
+			},
+		},
+		{
+			name: "test for remove",
+			args: args{
+				logStrategy: "remove",
+				logFile:     logFile[1],
+			},
+		},
+		{
+			name: "test for preserve",
+			args: args{
+				logStrategy: "preserve",
+				logFile:     logFile[2],
+			},
+		},
+	}
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			strategicActionOnLogFile(ctx, tt.args.logStrategy, tt.args.logFile)
+
+			var err error
+			switch tt.args.logStrategy {
+			case "compress":
+				newExt := strings.Replace(tt.args.logFile, ".log", ".gz", -1)
+				if _, err = os.Stat(newExt); os.IsNotExist(err) {
+					t.Errorf("compressed logFile (%s) not found: %v", newExt, err)
+				}
+				os.Remove(newExt)
+			case "remove":
+				if _, err = os.Stat(tt.args.logFile); !os.IsNotExist(err) {
+					t.Errorf("logFile (%s) not removed: %v", tt.args.logFile, err)
+				}
+			case "preserve":
+				if _, err = os.Stat(tt.args.logFile); os.IsNotExist(err) {
+					t.Errorf("logFile (%s) not preserved: %v", tt.args.logFile, err)
+				}
+				os.Remove(tt.args.logFile)
+			}
+		})
+	}
+}