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/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)
+			}
+		})
+	}
+}