prometheus/tsdb/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"
"fmt"
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"io"
"os"
"path/filepath"
"github.com/go-kit/log"
"github.com/go-kit/log/level"
tsdb_errors "github.com/prometheus/prometheus/tsdb/errors"
"github.com/prometheus/prometheus/tsdb/fileutil"
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)
// 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 fmt.Errorf("list block dirs in %q: %w", dir, err)
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}
tmpFiles := make([]string, 0, len(dirs))
defer func() {
for _, tmp := range tmpFiles {
if err := os.RemoveAll(tmp); err != nil {
level.Error(logger).Log("msg", "remove tmp file", "err", err.Error())
}
}
}()
for _, d := range dirs {
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meta, err := readBogusMetaFile(d)
if err != nil {
level.Error(logger).Log("msg", "failed to read meta.json for a block during repair process; skipping", "dir", d, "err", err)
continue
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}
if meta.Version == metaVersion1 {
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 fmt.Errorf("create index.repaired for block dir: %v: %w", d, err)
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}
tmpFiles = append(tmpFiles, repl.Name())
broken, err := os.Open(filepath.Join(d, indexFilename))
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if err != nil {
return fmt.Errorf("open broken index for block dir: %v: %w", d, err)
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}
if _, err := io.Copy(repl, broken); err != nil {
return fmt.Errorf("copy content of index to index.repaired for block dir: %v: %w", d, err)
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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 {
errs := tsdb_errors.NewMulti(
fmt.Errorf("rewrite of index.repaired for block dir: %v: %w", d, err))
if err := repl.Close(); err != nil {
errs.Add(fmt.Errorf("close: %w", err))
}
return errs.Err()
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}
if err := repl.Sync(); err != nil {
errs := tsdb_errors.NewMulti(
fmt.Errorf("sync of index.repaired for block dir: %v: %w", d, err))
if err := repl.Close(); err != nil {
errs.Add(fmt.Errorf("close: %w", err))
}
return errs.Err()
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}
if err := repl.Close(); err != nil {
return fmt.Errorf("close repaired index for block dir: %v: %w", d, err)
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}
if err := broken.Close(); err != nil {
if err := repl.Close(); err != nil {
return fmt.Errorf("close broken index for block dir: %v: %w", d, err)
}
}
if err := fileutil.Replace(repl.Name(), broken.Name()); err != nil {
if err := repl.Close(); err != nil {
return fmt.Errorf("replaced broken index with index.repaired for block dir: %v: %w", d, err)
}
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}
// Reset version of meta.json to 1.
meta.Version = metaVersion1
if _, err := writeMetaFile(logger, d, meta); err != nil {
if err := repl.Close(); err != nil {
return fmt.Errorf("write meta for block dir: %v: %w", d, err)
}
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}
}
return nil
}
func readBogusMetaFile(dir string) (*BlockMeta, error) {
b, err := os.ReadFile(filepath.Join(dir, metaFilename))
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if err != nil {
return nil, err
}
var m BlockMeta
if err := json.Unmarshal(b, &m); err != nil {
return nil, err
}
if m.Version != metaVersion1 && m.Version != 2 {
return nil, fmt.Errorf("unexpected meta file version %d", m.Version)
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}
return &m, nil
}