delete only valid ULID dirs, some better logging.

Signed-off-by: Krasi Georgiev <kgeorgie@redhat.com>

cmd/tsdb/main.go

@@ -20,6 +20,7 @@ import (
 	"io"
 	"io/ioutil"
 	"os"
+	"path"
 	"path/filepath"
 	"runtime"
 	"runtime/pprof"
@@ -31,6 +32,7 @@ import (
 	"time"
 
 	"github.com/go-kit/kit/log"
+	"github.com/oklog/ulid"
 	"github.com/pkg/errors"
 	"github.com/prometheus/tsdb"
 	"github.com/prometheus/tsdb/labels"
@@ -92,7 +94,10 @@ are safe to delete as long as you are sure that no other application is currentl
 			exitWithError(err)
 		}
 
-		for err, unreadable := range scanner.Scan() {
+		var unreadable []*tsdb.Block
+		for err, unreadable = range scanner.Scan() {
+			fmt.Printf("\nCorrupted blocks : %v \nDeleting these will remove all data in the listed time range.\n\n", err)
+
 			switch err.(type) {
 			case tsdb.ErrOverlap:
 				var biggestIndex int
@@ -106,15 +111,16 @@ are safe to delete as long as you are sure that no other application is currentl
 				// Don't delete the bigest block in the overlaps.
 				unreadable = append(unreadable[:biggestIndex], unreadable[biggestIndex+1:]...)
 
-				fmt.Printf("\n%v \nDeleting these will loose all data in the listed time ranges.\n\n", err)
-				fmt.Printf("\nBlock %v contains most samples  is ommited from the list and it won't be deleted! \n\n", biggest)
-
-			default:
-				fmt.Printf("\nUnreadable blocks : %v \nDeleting these will loose all data in the listed time ranges.\n\n", err)
-
+				fmt.Printf("\nBlock %v contains most samples and is ommited from the deletion listgit ! \n\n", biggest)
 			}
 			promptDelete(unreadable, scanCmdHumanReadable)
 		}
+
+		fmt.Println("Scan complete!")
+		if len(unreadable) == 0 {
+			fmt.Println("Hooray! The db is clean(or the scan tool is broken).\U0001f638")
+			return
+		}
 	}
 	flag.CommandLine.Set("log.level", "debug")
 }
@@ -144,9 +150,14 @@ func promptDelete(i interface{}, humanReadable *bool) {
 	s = strings.ToLower(s)
 
 	if s == "y" || s == "yes" {
-		for _, path := range paths {
-			if err := os.Remove(path); err != nil {
-				fmt.Printf("error deleting: %v, %v", path, err)
+		for _, p := range paths {
+			_, folder := path.Split(p)
+			if _, err := ulid.Parse(folder); err != nil {
+				exitWithError(fmt.Errorf("dir doesn't contain a valid ULID:%v", err))
+			}
+
+			if err := os.RemoveAll(p); err != nil {
+				fmt.Printf("error deleting: %v, %v", p, err)
 			}
 		}
 		return