---
layout: wiki
title: TracLogging
updated: 2021-04-16 08:14
author: trac
default: true
---

## Trac Logging

Trac supports logging of system messages using Python's [logging module](https://docs.python.org/2/library/logging.html).

Logging is configured in the "[logging"\] section of [TracIni](/briareus/notes/TracIni/).

### Supported Logging Methods

The log method is set using the "[logging log_type"\] option, which accepts the following values:

- ***'none*** - Suppress all log messages.
- ****file**** - Log messages to a file, specified with the "[logging log_file"\] option. Relative paths for \`log_file\` are resolved relative to the environment \`log\` directory.
- ****stderr**** - Output log entries to console ([tracd](/briareus/notes/TracStandalone/) only).
- ****syslog**** - (UNIX) Send log messages to the local syslogd via named pipe \`/dev/log\`. By default, syslog will write them to the \`/var/log/messages\` file.
- ****eventlog**** - (Windows) Use the system's NT Event Log.

### Log Levels

The verbosity level of logged messages can be set using the "[logging log_level"\] option. The log level defines the minimum level of urgency required for a message to be logged, and those levels are:

- ****CRITICAL**** - Log only the most critical (typically fatal) errors.
- ****ERROR**** - Log failures, bugs and errors.
- ****WARN**** - Log warnings, non-interrupting events.
- ****INFO**** - Diagnostic information, log information about all processing.
- ****DEBUG**** - Trace messages, profiling, etc.

Additionally, you can  enable logging of SQL statements at debug level. This is turned off by default, as it's very verbose. Set "[trac debug_sql  = yes"\] to activate.

### Log Format

The output format for log entries can be specified in the "[logging log_format"\] option. The format is a string which can contain any of the [Python logging Formatter variables](https://docs.python.org/2/library/logging.html#logrecord-attributes). Additionally, the following Trac-specific variables can be used:

- ****$(basename)s**** - The environment directory name.
- ****$(path)s**** - The absolute path of the environment directory.
- ****$(project)s**** - The originating project's name.

Note that variables are identified using a dollar sign (\`$(...)s\`) instead of percent sign (\`%(...)s\`).

The default format is:

```ini
log_format = Trac[$(module)s] $(levelname)s: $(message)s
```

In a multi-project environment where all logs are sent to the same place (e.g. \`syslog\`), it makes sense to add the project name. In this example we use \`basename\` since that can generally be used to identify a project:

```ini
log_format = Trac[$(basename)s:$(module)s] $(levelname)s: $(message)s
```

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See also: [TracIni](/briareus/notes/TracIni/), [TracEnvironment](/briareus/notes/TracEnvironment/)