Log

The log block configures sing-box's logger: severity, where to write, whether to include a timestamp, and whether to disable logging entirely.

Options

Field	Type	Default	Allowed values	Description
disabled	bool	false	true | false	When true, sing-box installs a no-op log factory. Nothing is written anywhere, regardless of other fields.
level	string	trace	trace | debug | info | warn | warning | error | fatal | panic	Minimum severity. An empty string is treated as the default. The keywords "warn" and "warning" are accepted aliases.
output	string	(stderr)	<empty> | stderr | stdout | <file path>	Where to write log lines. Empty defaults to stderr; "stderr" and "stdout" are the literal stream names; any other value is treated as a file path.
timestamp	bool	false	true | false	When true, every line is prefixed with a timestamp like "-0700 2006-01-02 15:04:05". Required for the timestamp to appear in file output.

Source: option/options.go:40-46 · pinned at v1.13.11 (553cfa1)

Examples

Default behavior (file omits log entirely — equivalent to {}):

{
  "log": {}
}

Quiet sing-box for a deployment:

{
  "log": {
    "level": "warn",
    "timestamp": true,
    "output": "/var/log/sing-box.log"
  }
}

Disable logging entirely:

{
  "log": {
    "disabled": true
  }
}

Notes

• The default level when level is left empty is trace (the most verbose tier), not info — see log/log.go:67-69. Most production configurations should set level explicitly.
• output of "stderr" and "stdout" are literal stream names; any other non-empty value is treated as a file path (log/log.go:32-45).
• When writing to a file, colors are forced off and timestamps are forced on regardless of the timestamp setting — see the formatter setup at log/log.go:46-52.

Source: option/options.go:40-46 · v1.13.11 (553cfa1)