patroni.log module¶
Patroni logging facilities.
Daemon processes will use a 2-step logging handler. Whenever a log message is issued it is initially enqueued in-memory and is later asynchronously flushed by a thread to the final destination.
-
class
patroni.log.
PatroniLogger
¶ Bases:
threading.Thread
Logging thread for the Patroni daemon process.
It is a 2-step logging approach. Any time a log message is issued it is initially enqueued in-memory, and then asynchronously flushed to the final destination by the logging thread.
See also
QueueHandler
: object used for enqueueing messages in-memory.Variables: - DEFAULT_TYPE – default type of log format (
plain
). - DEFAULT_LEVEL – default logging level (
INFO
). - DEFAULT_TRACEBACK_LEVEL – default traceback logging level (
ERROR
). - DEFAULT_FORMAT – default format of log messages (
%(asctime)s %(levelname)s: %(message)s
). - NORMAL_LOG_QUEUE_SIZE – expected number of log messages per HA loop when operating under a normal situation.
- DEFAULT_MAX_QUEUE_SIZE – default maximum queue size for holding a backlog of log messages that are pending to be flushed.
- LOGGING_BROKEN_EXIT_CODE – exit code to be used if it detects(
5
). - log_handler – log handler that is currently being used by the thread.
- log_handler_lock – lock used to modify
log_handler
.
-
DEFAULT_FORMAT
= '%(asctime)s %(levelname)s: %(message)s'¶
-
DEFAULT_LEVEL
= 'INFO'¶
-
DEFAULT_MAX_QUEUE_SIZE
= 1000¶
-
DEFAULT_TRACEBACK_LEVEL
= 'ERROR'¶
-
DEFAULT_TYPE
= 'plain'¶
-
LOGGING_BROKEN_EXIT_CODE
= 5¶
-
NORMAL_LOG_QUEUE_SIZE
= 2¶
-
__init__
() → None¶ Prepare logging queue and proxy handlers as they become ready during daemon startup.
Note
While Patroni is starting up it keeps
DEBUG
log level, and writes log messages through a proxy handler. Once the logger thread is finally started, it switches from that proxy handler to the queue based logger, and applies the configured log settings. The switching is used to avoid that the logger thread prevents Patroni from shutting down if any issue occurs in the meantime until the thread is properly started.
-
_close_old_handlers
() → None¶ Close old log handlers.
Note
It is used to remove different handlers that were configured previous to a reload in the configuration, e.g. if we are switching from
RotatingFileHandler
to class:~logging.StreamHandler and vice-versa.
-
_get_formatter
(config: Dict[str, Any]) → logging.Formatter¶ Returns a logging formatter based on the type of logger in the given configuration.
Parameters: config – log
section from Patroni configuration.Returns: A logging.Formatter
object that can be used to format log records.
-
_get_json_formatter
(logformat: Union[List[Union[str, Dict[str, Any], Any]], str, Any], dateformat: Optional[str], static_fields: Dict[str, Any]) → logging.Formatter¶ Returns a logging formatter that outputs JSON formatted messages.
Note
If
pythonjsonlogger
library is not installed, prints an error message and returns a plain log formatter instead.Parameters: - logformat – Specifies the log fields and their key names in the JSON log message.
- dateformat – The format of the timestamp in the log messages.
- static_fields – A dictionary of static fields that are added to every log message.
Returns: A logging formatter object that can be used to format log records as JSON strings.
-
_get_plain_formatter
(logformat: Union[List[Union[str, Dict[str, Any], Any]], str, Any], dateformat: Optional[str]) → logging.Formatter¶ Returns a logging formatter with the specified format and date format.
Note
If the log format isn’t a string, prints a warning message and uses the default log format instead.
Parameters: - logformat – The format of the log messages.
- dateformat – The format of the timestamp in the log messages.
Returns: A logging formatter object that can be used to format log records.
-
_is_config_changed
(config: Dict[str, Any]) → bool¶ Checks if the given config is different from the current one.
Parameters: config – log
section from Patroni configuration.Returns: True
if the config is changed,False
otherwise.
-
queue_size
¶ Number of log records in the queue.
-
records_lost
¶ Number of logging records that have been lost while the queue was full.
-
reload_config
(config: Dict[str, Any]) → None¶ Apply log related configuration.
Note
It is also able to deal with runtime configuration changes.
Parameters: config – log
section from Patroni configuration.
-
run
() → None¶ Run logger’s thread main loop.
Keep consuming log queue until requested to quit through
None
special log record.
-
shutdown
() → None¶ Shut down the logger thread.
-
update_loggers
(config: Dict[str, Any]) → None¶ Configure custom loggers’ log levels.
Note
It creates logger objects that are not defined yet in the log manager.
Parameters: config –
dict
object with custom loggers configuration, is set either from:log.loggers
section of Patroni configuration; or- from the method that is trying to make sure that the node name
isn’t duplicated (to silence annoying
urllib3
WARNING’s).
Example: update_loggers({'urllib3.connectionpool': 'WARNING'})
- DEFAULT_TYPE – default type of log format (
-
class
patroni.log.
ProxyHandler
(patroni_logger: patroni.log.PatroniLogger)¶ Bases:
logging.Handler
Handle log records in place of pending log handlers.
Note
This is used to handle log messages while the logger thread has not started yet, in which case the queue-based handler is not yet started.
Variables: patroni_logger – the logger thread. -
__init__
(patroni_logger: patroni.log.PatroniLogger) → None¶ Create a new
ProxyHandler
instance.Parameters: patroni_logger – the logger thread.
-
emit
(record: logging.LogRecord) → None¶ Emit each log record that is handled.
Will push the log record down to
handle()
method of the currently configured log handler.Parameters: record – the record that was emitted.
-
-
class
patroni.log.
QueueHandler
¶ Bases:
logging.Handler
Queue-based logging handler.
Variables: queue – queue to hold log messages that are pending to be flushed to the final destination. -
__init__
() → None¶ Queue initialised and initial records_lost established.
-
_put_record
(record: logging.LogRecord) → None¶ Asynchronously enqueue a log record.
Parameters: record – the record to be logged.
-
_try_to_report_lost_records
() → None¶ Report the number of log messages that have been lost and reset the counter.
Note
It will issue an
WARNING
message in the logs with the number of lost log messages.
-
emit
(record: logging.LogRecord) → None¶ Handle each log record that is emitted.
Call
_put_record()
to enqueue the emitted log record.Also check if we have previously lost any log record, and if so, log a
WARNING
message.Parameters: record – the record that was emitted.
-
records_lost
¶ Number of log messages that have been lost while the queue was full.
-
-
patroni.log.
debug_exception
(self: logging.Logger, msg: object, *args, **kwargs) → None¶ Add full stack trace info to debug log messages and partial to others.
Handle
exception()
calls for self.Note
- If self log level is set to
DEBUG
, then issue aDEBUG
message with the complete stack trace; - If self log level is
INFO
or higher, then issue anERROR
message with only the last line of - the stack trace.
- If self log level is
Parameters: - self – logger for which
exception()
will be processed. - msg – the message related to the exception to be logged.
- args – positional arguments to be passed to
debug()
orerror()
. - kwargs – keyword arguments to be passed to
debug()
orerror()
.
- If self log level is set to
-
patroni.log.
error_exception
(self: logging.Logger, msg: object, *args, **kwargs) → None¶ Add full stack trace info to error messages.
Handle
exception()
calls for self.Note
- By default issue an
ERROR
message with the complete stack trace. If you do not want to show the complete stack trace, call withexc_info=False
.
Parameters: - self – logger for which
exception()
will be processed. - msg – the message related to the exception to be logged.
- args – positional arguments to be passed to
error()
. - kwargs – keyword arguments to be passed to
error()
.
- By default issue an