thanos-io/thanos · error

get compaction levels

Error message

get compaction levels

What it means

Wraps errors.Errorf returned by compactionSet.levels when --max-compaction-level exceeds the configured compaction level set (see error 0). runCompact adds this context so the operator knows the compaction-level flag is the problem.

Solutions

1. Set --max-compaction-level to a valid value (e.g. 2 for the default 3-level set).
2. Remove the --max-compaction-level flag to accept defaults.
3. If a higher level is genuinely needed, upgrade Thanos / use a build with a larger default level set.

Example fix

// before
thanos compact --max-compaction-level=4 ...
// after
thanos compact --max-compaction-level=2 ...

if maxCompactionLevel < 0 || maxCompactionLevel >= len(thanos.CompactionLevels) {
    return fmt.Errorf("--max-compaction-level out of range: %d", maxCompactionLevel)
}

When it happens

Trigger: runCompact with conf.maxCompactionLevel >= len(compactions), i.e. --max-compaction-level set to 4 or higher than the number of default levels.

Common situations: Operators misreading the flag as an absolute TSDB level (e.g. setting 4 to "allow level-4 blocks") instead of an index bound.

Understand the failure class

Background: "value must be between 0 and 1" / "out of range" / "must not be negative" errors: fixing range-validation failures across open-source libraries — this error's family across 42 libraries.

Related errors

• level is bigger then default set of
• unknown sync strategy
• penalty based deduplication needs at least one replica…
• unrecognized label
• unsupported format for label

AI-assisted analysis of thanos-io/thanos@35b8b99117 (2026-09-07). Data as JSON: /api/errors/338a43369baa654f. Report an issue: GitHub.

Appendix: source

Thrown at cmd/thanos/compact.go:312

		sy, err = compact.NewMetaSyncer(
			logger,
			reg,
			insBkt,
			cf,
			duplicateBlocksFilter,
			ignoreDeletionMarkFilter,
			compactMetrics.blocksMarked.WithLabelValues(metadata.DeletionMarkFilename, ""),
			compactMetrics.garbageCollectedBlocks,
			syncMetasTimeout,
		)
		if err != nil {
			return errors.Wrap(err, "create syncer")
		}
	}

	levels, err := compactions.levels(conf.maxCompactionLevel)
	if err != nil {
		return errors.Wrap(err, "get compaction levels")
	}

	if conf.maxCompactionLevel < compactions.maxLevel() {
		level.Warn(logger).Log("msg", "Max compaction level is lower than should be", "current", conf.maxCompactionLevel, "default", compactions.maxLevel())
	}

	ctx, cancel := context.WithCancel(context.Background())
	ctx = tracing.ContextWithTracer(ctx, tracer)

	defer func() {
		if rerr != nil {
			cancel()
		}
	}()

	var mergeFunc storage.VerticalChunkSeriesMergeFunc
	switch conf.dedupFunc {
	case compact.DedupAlgorithmPenalty:

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