prometheus/repair.go

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// Copyright 2018 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
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package tsdb
import (
"encoding/json"
"io"
"io/ioutil"
"os"
"path/filepath"
"github.com/go-kit/kit/log"
"github.com/go-kit/kit/log/level"
"github.com/pkg/errors"
"github.com/prometheus/tsdb/fileutil"
)
// repairBadIndexVersion repairs an issue in index and meta.json persistence introduced in
// commit 129773b41a565fde5156301e37f9a87158030443.
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func repairBadIndexVersion(logger log.Logger, dir string) error {
// All blocks written by Prometheus 2.1 with a meta.json version of 2 are affected.
// We must actually set the index file version to 2 and revert the meta.json version back to 1.
dirs, err := blockDirs(dir)
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if err != nil {
return errors.Wrapf(err, "list block dirs in %q", dir)
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}
wrapErr := func(err error, d string) error {
return errors.Wrapf(err, "block dir: %q", d)
}
for _, d := range dirs {
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meta, err := readBogusMetaFile(d)
if err != nil {
return wrapErr(err, d)
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}
if meta.Version == 1 {
level.Info(logger).Log(
"msg", "found healthy block",
"mint", meta.MinTime,
"maxt", meta.MaxTime,
"ulid", meta.ULID,
)
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continue
}
level.Info(logger).Log(
"msg", "fixing broken block",
"mint", meta.MinTime,
"maxt", meta.MaxTime,
"ulid", meta.ULID,
)
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repl, err := os.Create(filepath.Join(d, "index.repaired"))
if err != nil {
return wrapErr(err, d)
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}
broken, err := os.Open(filepath.Join(d, "index"))
if err != nil {
return wrapErr(err, d)
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}
if _, err := io.Copy(repl, broken); err != nil {
return wrapErr(err, d)
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}
// Set the 5th byte to 2 to indicate the correct file format version.
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if _, err := repl.WriteAt([]byte{2}, 4); err != nil {
return wrapErr(err, d)
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}
if err := fileutil.Fsync(repl); err != nil {
return wrapErr(err, d)
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}
if err := repl.Close(); err != nil {
return wrapErr(err, d)
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}
if err := broken.Close(); err != nil {
return wrapErr(err, d)
}
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if err := renameFile(repl.Name(), broken.Name()); err != nil {
return wrapErr(err, d)
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}
// Reset version of meta.json to 1.
meta.Version = 1
if err := writeMetaFile(d, meta); err != nil {
return wrapErr(err, d)
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}
}
return nil
}
func readBogusMetaFile(dir string) (*BlockMeta, error) {
b, err := ioutil.ReadFile(filepath.Join(dir, metaFilename))
if err != nil {
return nil, err
}
var m BlockMeta
if err := json.Unmarshal(b, &m); err != nil {
return nil, err
}
if m.Version != 1 && m.Version != 2 {
return nil, errors.Errorf("unexpected meta file version %d", m.Version)
}
return &m, nil
}