storage: write min version file with checkpoint

We now write out the min version file with checkpoints generated
through the storage layer. This allows checkpoints to be opened with
the cockroach storage layer (not just with the low level pebble tool).

Informs cockroachdb#97337

Release note: None
Epic: none

pkg/storage/engine_test.go

@@ -1004,15 +1004,26 @@ func TestCreateCheckpoint(t *testing.T) {
 	assert.NoError(t, err)
 	defer db.Close()
 
-	dir = filepath.Join(dir, "checkpoint")
+	checkpointDir := filepath.Join(dir, "checkpoint")
 
 	assert.NoError(t, err)
-	assert.NoError(t, db.CreateCheckpoint(dir, nil))
-	assert.DirExists(t, dir)
-	m, err := filepath.Glob(dir + "/*")
+	assert.NoError(t, db.CreateCheckpoint(checkpointDir, nil))
+	assert.DirExists(t, checkpointDir)
+	m, err := filepath.Glob(checkpointDir + "/*")
 	assert.NoError(t, err)
 	assert.True(t, len(m) > 0)
-	if err := db.CreateCheckpoint(dir, nil); !testutils.IsError(err, "exists") {
+
+	// Verify that we can open the checkpoint.
+	db2, err := Open(
+		context.Background(),
+		Filesystem(checkpointDir),
+		cluster.MakeTestingClusterSettings(),
+		MustExist)
+	require.NoError(t, err)
+	db2.Close()
+
+	// Verify that creating another checkpoint in the same directory fails.
+	if err := db.CreateCheckpoint(checkpointDir, nil); !testutils.IsError(err, "exists") {
 		t.Fatal(err)
 	}
 }

pkg/storage/pebble.go

@@ -1950,11 +1950,21 @@ func (p *Pebble) CreateCheckpoint(dir string, spans []roachpb.Span) error {
 		return err
 	}
 
+	// Write out the min version file.
+	if err := writeMinVersionFile(p.unencryptedFS, dir, p.MinVersion()); err != nil {
+		return errors.Wrapf(err, "writing min version file for checkpoint")
+	}
+
 	// TODO(#90543, cockroachdb/pebble#2285): move spans info to Pebble manifest.
 	if len(spans) > 0 {
-		return fs.SafeWriteToFile(p.fs, dir, p.fs.PathJoin(dir, "checkpoint.txt"),
-			checkpointSpansNote(spans))
+		if err := fs.SafeWriteToFile(
+			p.fs, dir, p.fs.PathJoin(dir, "checkpoint.txt"),
+			checkpointSpansNote(spans),
+		); err != nil {
+			return err
+		}
 	}
+
 	return nil
 }