thanos-io/thanos · error

expand environment variables

Error message

expand environment variables

What it means

Wraps r.expandEnv in Reloader.normalize: expanding environment variables in the config failed, typically an unbalanced ${VAR or other os.Expand syntax problem introduced by a malformed ${...} template in the config.

Solutions

1. Define all referenced environment variables in the pod/secret.
2. Check for typos or unsupported syntax in ${VAR} placeholders.
3. Inspect the wrapped error for the offending variable.

When it happens

Trigger: Thrown at pkg/reloader/reloader.go:383 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of thanos-io/thanos@35b8b99117 (2026-09-07). Data as JSON: /api/errors/d76286c6db732ad1. Report an issue: GitHub.

Appendix: source

Thrown at pkg/reloader/reloader.go:383

	}

	// Detect and extract gzipped file.
	if bytes.Equal(b[0:3], firstGzipBytes) {
		zr, err := gzip.NewReader(bytes.NewReader(b))
		if err != nil {
			return errors.Wrap(err, "create gzip reader")
		}
		defer runutil.CloseWithLogOnErr(r.logger, zr, "gzip reader close")

		b, err = io.ReadAll(zr)
		if err != nil {
			return errors.Wrap(err, "read compressed config file")
		}
	}

	b, err = r.expandEnv(b)
	if err != nil {
		return errors.Wrap(err, "expand environment variables")
	}

	tmpFile := outputFile + ".tmp"
	defer func() {
		_ = os.Remove(tmpFile)
	}()
	if err := os.WriteFile(tmpFile, b, 0644); err != nil {
		return errors.Wrap(err, "write file")
	}
	if err := os.Rename(tmpFile, outputFile); err != nil {
		return errors.Wrap(err, "rename file")
	}
	return nil
}

// apply triggers Prometheus reload if rules or config changed. If cfgOutputFile is set, we also
// expand env vars into config file before reloading.
// Reload is retried in retryInterval until watchInterval.

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