1// Copyright 2018 The Prometheus Authors
2// Licensed under the Apache License, Version 2.0 (the "License");
3// you may not use this file except in compliance with the License.
4// You may obtain a copy of the License at
5//
6// http://www.apache.org/licenses/LICENSE-2.0
7//
8// Unless required by applicable law or agreed to in writing, software
9// distributed under the License is distributed on an "AS IS" BASIS,
10// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
11// See the License for the specific language governing permissions and
12// limitations under the License.
13
14package tsdb
15
16import (
17	"encoding/json"
18	"io"
19	"io/ioutil"
20	"os"
21	"path/filepath"
22
23	"github.com/go-kit/kit/log"
24	"github.com/go-kit/kit/log/level"
25	"github.com/pkg/errors"
26	"github.com/prometheus/tsdb/fileutil"
27)
28
29// repairBadIndexVersion repairs an issue in index and meta.json persistence introduced in
30// commit 129773b41a565fde5156301e37f9a87158030443.
31func repairBadIndexVersion(logger log.Logger, dir string) error {
32	// All blocks written by Prometheus 2.1 with a meta.json version of 2 are affected.
33	// We must actually set the index file version to 2 and revert the meta.json version back to 1.
34	dirs, err := blockDirs(dir)
35	if err != nil {
36		return errors.Wrapf(err, "list block dirs in %q", dir)
37	}
38
39	wrapErr := func(err error, d string) error {
40		return errors.Wrapf(err, "block dir: %q", d)
41	}
42	for _, d := range dirs {
43		meta, err := readBogusMetaFile(d)
44		if err != nil {
45			return wrapErr(err, d)
46		}
47		if meta.Version == 1 {
48			level.Info(logger).Log(
49				"msg", "found healthy block",
50				"mint", meta.MinTime,
51				"maxt", meta.MaxTime,
52				"ulid", meta.ULID,
53			)
54			continue
55		}
56		level.Info(logger).Log(
57			"msg", "fixing broken block",
58			"mint", meta.MinTime,
59			"maxt", meta.MaxTime,
60			"ulid", meta.ULID,
61		)
62
63		repl, err := os.Create(filepath.Join(d, "index.repaired"))
64		if err != nil {
65			return wrapErr(err, d)
66		}
67		broken, err := os.Open(filepath.Join(d, "index"))
68		if err != nil {
69			return wrapErr(err, d)
70		}
71		if _, err := io.Copy(repl, broken); err != nil {
72			return wrapErr(err, d)
73		}
74		// Set the 5th byte to 2 to indicate the correct file format version.
75		if _, err := repl.WriteAt([]byte{2}, 4); err != nil {
76			return wrapErr(err, d)
77		}
78		if err := fileutil.Fsync(repl); err != nil {
79			return wrapErr(err, d)
80		}
81		if err := repl.Close(); err != nil {
82			return wrapErr(err, d)
83		}
84		if err := broken.Close(); err != nil {
85			return wrapErr(err, d)
86		}
87		if err := renameFile(repl.Name(), broken.Name()); err != nil {
88			return wrapErr(err, d)
89		}
90		// Reset version of meta.json to 1.
91		meta.Version = 1
92		if err := writeMetaFile(d, meta); err != nil {
93			return wrapErr(err, d)
94		}
95	}
96	return nil
97}
98
99func readBogusMetaFile(dir string) (*BlockMeta, error) {
100	b, err := ioutil.ReadFile(filepath.Join(dir, metaFilename))
101	if err != nil {
102		return nil, err
103	}
104	var m BlockMeta
105
106	if err := json.Unmarshal(b, &m); err != nil {
107		return nil, err
108	}
109	if m.Version != 1 && m.Version != 2 {
110		return nil, errors.Errorf("unexpected meta file version %d", m.Version)
111	}
112	return &m, nil
113}
114