stogger.core

Core logging functionality for stogger.

Attributes

log
JOURNAL_LEVELS
KEYS_TO_SKIP_IN_JOURNAL_MESSAGE

Classes

PartialFormatter
TranslationProcessor
ConsoleFileRenderer	Render event_dict nicely aligned, in colors, and ordered with
JSONRenderer	JSON renderer for structured logging output.
SelectRenderedString	Processor that selects a string from the dict returned by ConsoleFileRenderer.
JournalLoggerFactory	Stub factory for systemd journal logger integration.
SystemdJournalRenderer	Render structlog events as systemd journal fields.
PostgresRenderer	Render event_dict into a column dict for PostgreSQL INSERT.
CmdOutputFileRenderer	Renderer for command output file logging.
MultiRenderer	Calls multiple renderers with a shallow copy of the event dict and collects
MultiOptimisticLoggerFactory	Factory that creates MultiOptimisticLogger instances.
MultiOptimisticLogger	Distribute log messages to multiple sub-loggers by target name.

Functions

prefix(name, s)	Add a prefix to each line of a multi-line string.
add_pid(_logger, _method_name, event_dict)
add_caller_info(_logger, _method_name, event_dict)
process_exc_info(_logger, _method_name, event_dict)
format_exc_info(_logger, _name, event_dict)	Renders exc_info if it's present.
log_to_stdlib(_logger, _name, event_dict)	Bridge structlog events to Python's standard library logging module.
init_logging(*[, logdir, log_cmd_output, ...])	Initialize full structured logging with console, file, and journal targets.
init_early_logging(*[, verbose])	Initialize minimal structured logging before full setup.
init_command_logging(log[, logdir])	Add a command output file logger to the active multi-logger factory.
drop_cmd_output_logfile(log)	Close and delete the command output log file.
logging_initialized()	Check whether structured logging has been configured.

Module Contents

stogger.core.log

class stogger.core.PartialFormatter(missing='<missing>', bad_format='<bad format>')

Bases: string.Formatter

missing = '<missing>'

bad_format = '<bad format>'

get_field(field_name, args, kwargs)

format_field(value, format_spec)

class stogger.core.TranslationProcessor(translations)

translations

formatter

stogger.core.prefix(name, s)

Add a prefix to each line of a multi-line string.

class stogger.core.ConsoleFileRenderer(format_config=None, min_level=None, show_caller_info=None)

Render event_dict nicely aligned, in colors, and ordered with specific knowledge about stogger structures.

LEVELS: ClassVar[list[str]] = ['alert', 'critical', 'error', 'exception', 'warn', 'warning', 'info', 'debug', 'trace']

format_config = None

min_level

show_caller_info

pad_event

show_logger_brackets = False

show_pid = False

timestamp_format

class stogger.core.JSONRenderer(min_level='info')

JSON renderer for structured logging output.

min_level_idx

stogger.core.add_pid(_logger, _method_name, event_dict)

Parameters:

• _logger (object)

• _method_name (str)

• event_dict (stogger._types.EventDict)

Return type:

stogger._types.EventDict

stogger.core.add_caller_info(_logger, _method_name, event_dict)

Parameters:

• _logger (object)

• _method_name (str)

• event_dict (stogger._types.EventDict)

Return type:

stogger._types.EventDict

stogger.core.process_exc_info(_logger, _method_name, event_dict)

Parameters:

• _logger (object)

• _method_name (str)

• event_dict (stogger._types.EventDict)

Return type:

stogger._types.EventDict

stogger.core.format_exc_info(_logger, _name, event_dict)

Renders exc_info if it’s present. Expects the tuple format returned by sys.exc_info(). Compared to structlog’s format_exc_info(), this renders the exception information separately which is better for structured logging targets.

Parameters:

• _logger (object)

• _name (str)

• event_dict (stogger._types.EventDict)

Return type:

stogger._types.EventDict

class stogger.core.SelectRenderedString(key='console')

Processor that selects a string from the dict returned by ConsoleFileRenderer.

This ensures that structlog.stdlib.ProcessorFormatter receives a string as required, avoiding RuntimeWarnings.

Parameters:

key (str)

key = 'console'

stogger.core.log_to_stdlib(_logger, _name, event_dict)

Bridge structlog events to Python’s standard library logging module.

This processor forwards every structlog event to logging.log() so that tools relying on stdlib handlers (e.g. pytest caplog) can capture them.

Do NOT add this to the default processor pipeline. Stogger configures its own renderers and file handlers. Adding this processor causes every event to appear twice — once via stogger’s MultiRenderer and once via the stdlib root logger.

Use cases where this is useful:

• Legacy code that reads from stdlib logging handlers

• Ad-hoc debugging with logging.basicConfig()

For test assertions, prefer pytest-structlog which captures events directly from the structlog pipeline without needing a stdlib bridge.

Args:

_logger: The structlog logger (unused). _name: The log method name (unused). event_dict: The structured event dictionary.

Returns:

The unmodified event_dict (pass-through processor).

Parameters:

• _logger (object)

• _name (str)

• event_dict (stogger._types.EventDict)

Return type:

stogger._types.EventDict

stogger.core.init_logging(*, logdir=None, log_cmd_output=False, log_to_console=True, syslog_identifier=None, verbose=None, show_caller_info=None)

Initialize full structured logging with console, file, and journal targets.

Configures structlog with a multi-target rendering pipeline: systemd journal, optional command output file, and a colorized console/file renderer. Sets up processors for PID, log level, exception formatting, timestamps, and caller info.

Args:

logdir: Directory for log files. A {syslog_identifier}.log file is created

here when writable. Required if log_cmd_output is True.

log_cmd_output: Enable separate command output logging to a dedicated file

in logdir. Requires logdir to be set.

log_to_console: Log to stderr. Disabled automatically when running under

systemd journal (detected via JOURNAL_STREAM env var).

syslog_identifier: Identifier string for syslog/journal entries. Also used

as the main log file name ({syslog_identifier}.log). When None (default), uses the value from settings (syslog_identifier in [tool.stogger] config).

verbose: When True, sets the console log level to "debug".

When None (default), uses the level from settings (typically "info").

show_caller_info: Whether to display code location (file, function, line)

in console output. When None (default), uses the setting from FormatConfig.show_code_info.

Raises:

ValueError: If log_cmd_output is True but logdir is not set.

Parameters:

• logdir (str | pathlib.Path | None)

• log_cmd_output (bool)

• log_to_console (bool)

• syslog_identifier (str | None)

• verbose (bool | None)

• show_caller_info (bool | None)

Return type:

None

stogger.core.init_early_logging(*, verbose=False)

Initialize minimal structured logging before full setup.

Configures a lightweight structlog pipeline (timestamp, level, console renderer) so that early startup messages are properly formatted instead of appearing as raw dicts. No-op if structlog is already configured. Errors during setup are suppressed to avoid crashing during early initialization, but logged at debug level.

Args:

verbose: When True, emit debug messages showing the caller that invoked

this function. Also enabled when the STOGGER_DEBUG environment variable is set.

Parameters:

verbose (bool)

Return type:

None

class stogger.core.JournalLoggerFactory

Stub factory for systemd journal logger integration.

Returns None by default. Actual systemd journal support is provided by the stogger-systemd package, which replaces this factory with a real journal writer. Use this as a placeholder so logging pipelines work without the systemd extra installed.

stogger.core.JOURNAL_LEVELS

stogger.core.KEYS_TO_SKIP_IN_JOURNAL_MESSAGE = ['_output', '_raw_output', '_raw_output_prefix', '_replace_msg', 'code_file', 'code_func',...

class stogger.core.SystemdJournalRenderer(syslog_identifier, syslog_facility=syslog.LOG_LOCAL0)

Render structlog events as systemd journal fields.

Transforms event dicts into journal-compatible key-value pairs with uppercased field names, syslog priority/facility, and a human-readable message string. Strings are kept un-JSON-encoded to preserve line breaks in journalctl output.

Args:

syslog_identifier: Identifier string for SYSLOG_IDENTIFIER field. syslog_facility: Syslog facility code (default: syslog.LOG_LOCAL0).

syslog_identifier

syslog_facility = 128

handle_json_fallback(obj)

Same as structlog’s json fallback. Supports obj.__structlog__() for custom object serialization.

dump_for_journal(obj)

Encode values as JSON, except strings. We keep strings unchanged to display line breaks properly in journalctl and graylog.

class stogger.core.PostgresRenderer

Render event_dict into a column dict for PostgreSQL INSERT.

Extracts known columns (timestamp, level, event, func, scope) and packs remaining fields into JSONB data.

KNOWN_FIELDS

class stogger.core.CmdOutputFileRenderer

Renderer for command output file logging.

class stogger.core.MultiRenderer(**renderers)

Calls multiple renderers with a shallow copy of the event dict and collects their messages in a dict with the renderer names as keys and their rendered output as values. It doesn’t care about the rendered messages so different logger types can get different types of messages. Normally, this should be placed last in the processors chain. Errors in renderers are ignored silently.

renderers

class stogger.core.MultiOptimisticLoggerFactory(context, factories)

Factory that creates MultiOptimisticLogger instances.

Holds shared context (e.g. logdir) and a dict of sub-logger factories (e.g. "console" → PrintLoggerFactory, "file" → PrintLoggerFactory). Each factory is called once per MultiOptimisticLogger instantiation.

Args:

context: Shared context dict available to all created loggers. factories: Dict mapping target names to structlog logger factory callables.

context

factories

class stogger.core.MultiOptimisticLogger(loggers)

Distribute log messages to multiple sub-loggers by target name.

Receives a dict of rendered outputs keyed by target name (e.g. "console", "file", "journal") and dispatches each to the corresponding sub-logger. Targets not present in the message are skipped. Errors in individual sub-loggers are caught and reported to stdlib logging to prevent one failing target from affecting others.

Args:

loggers: Dict mapping target names to structlog logger instances.

loggers

msg(**messages)

Return type:

None

stogger.core.init_command_logging(log, logdir=None)

Add a command output file logger to the active multi-logger factory.

Opens (or overwrites) a dedicated log file for capturing subprocess command output separately from the main log. When running under systemd (detected via INVOCATION_ID env var), the filename includes a timestamp and invocation ID for uniqueness.

Args:

log: A structlog BoundLogger instance (typically from structlog.get_logger()). logdir: Directory for the command output file. Falls back to the

logdir stored in the current MultiOptimisticLoggerFactory context.

Return type:

None

stogger.core.drop_cmd_output_logfile(log)

Close and delete the command output log file.

Removes the file created by init_command_logging. Use this when no meaningful command output was produced to avoid leaving empty log files.

Args:

log: A structlog BoundLogger instance for diagnostic messages.

Raises:

KeyError: If the cmd_output_file factory is not present in the

active MultiOptimisticLoggerFactory (i.e. init_command_logging was never called).

Return type:

None

stogger.core.logging_initialized()

Check whether structured logging has been configured.

Returns:

True if init_logging or init_early_logging has been called successfully, False otherwise.