slimtoolkit/slim · error

failed to set log-level: %v

Error message

failed to set log-level: %v

What it means

configureLogger (called from Run) first applies the log level via setLogLevel, which combines the enableDebug flag with the --log-level name. If setLogLevel rejects the input (unknown level name or invalid combination), configureLogger wraps and returns this error, so the sensor fails fast at startup rather than logging silently.

Source

Thrown at pkg/app/sensor/logger.go:21

package sensor

import (
	"fmt"
	"os"

	log "github.com/sirupsen/logrus"
	"github.com/slimtoolkit/slim/pkg/util/fsutil"
)

func configureLogger(
	enableDebug bool,
	levelName string,
	format string,
	logFile string,
) error {
	if err := setLogLevel(enableDebug, levelName); err != nil {
		return fmt.Errorf("failed to set log-level: %v", err)
	}

	if err := setLogFormat(format); err != nil {
		return fmt.Errorf("failed to set log format: %v", err)
	}

	if len(logFile) > 0 {
		// This touch is not ideal - need to understand how to merge this logic with artifacts.PrepareEnv().
		if err := fsutil.Touch(logFile); err != nil {
			return fmt.Errorf("failed to set log output destination to %q, touch failed with: %v", logFile, err)
		}

		f, err := os.OpenFile(logFile, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0644)
		if err != nil {
			return fmt.Errorf("failed to set log output destination to %q: %w", logFile, err)
		}

		log.SetOutput(f)

View on GitHub (pinned to 81940d17fa)

Solutions

1. Set --log-level to a supported level name (e.g. debug, info, warn, error) as the wrapped %v error indicates.
2. Drop the custom level and rely on the boolean enableDebug flag for debug output.
3. Check the sensor's logger.go setLogLevel implementation for the exact accepted values.

Example fix

// before
args: ["--log-level", "verbose"]
// after
args: ["--log-level", "debug"]

var validLevels = map[string]bool{"debug": true, "info": true, "warn": true, "warning": true, "error": true, "fatal": true, "trace": true}
func validLogLevel(name string) bool { return validLevels[strings.ToLower(strings.TrimSpace(name))] }

func isLogLevelError(err error) bool {
    return err != nil && strings.Contains(err.Error(), "failed to set log-level")
}

if err := Run(ctx); err != nil && strings.Contains(err.Error(), "failed to set log-level") {
    fmt.Fprintf(os.Stderr, "bad --log-level, use debug|info|warn|error: %v\n", err)
    os.Exit(2)
}

When it happens

Trigger: Running the sensor with a --log-level value that setLogLevel cannot parse (e.g. 'verbose', 'warn2', typo like 'infro'), or a level string that conflicts with enableDebug handling.

Common situations: Deployment YAML passes a custom log level name the sensor does not support; configuration templating injects an empty or malformed level; users assume arbitrary zap/logrus level names are accepted.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

• failed to set log format: %v
• unknown log-format %q
• failed to set log output destination to %q, touch failed wit
• unknown log-level %q
• No global params

AI-assisted analysis of slimtoolkit/slim@81940d17fa (2026-08-31). Data as JSON: /api/errors/514328ea76f8cfab. Report an issue: GitHub.