dictconfig_example.yaml

# From https://docs.python.org/3/library/logging.config.html
# and https://docs.python.org/3/howto/logging.html#configuring-logging

# The logging system consists of four components:
# 1. Loggers.
# 2. Log record handlers - specifies what to do with a log record.
# 3. Log record filters - specifies which log records are actually displayed.
# 4. Log record formatters - specifies how a log record looks when it is is displayed.
# See https://docs.python.org/3/howto/logging.html#logging-flow for a informative diagram of the logging workflow.

# Loggers are hierarchical, the hierarchy specified by period-separated names:
# The logger `foo.bar.baz` has ancestors root <- foo <- foo.bar <- foo.bar.baz.
# If `propagate` is True, then (after passing LogRecords to all the logger's handlers)
# the LogRecord is passed to the logger's parent.

# More examples on how to configure logging using dictConfig files:
# * https://docs.python.org/3/howto/logging.html#configuring-logging
# * https://gist.github.com/cshoe/2777755
#

# dictConfig files must have a 'version' entry which must equal 1.
version: 1

formatters:
  brief:
    # configuration for formatter with id 'brief' goes here
    format: '%(message)s'
  precise:
    # configuration for formatter with id 'precise' goes here
    format: '%(asctime)s %(levelname)-8s %(name)-15s %(message)s'
    datefmt: '%Y-%m-%d %H:%M:%S'
  simple:
    format: '%(asctime)s - %(name)s - %(levelname)s - %(message)s'
filters:
  # Define logging filters, c.f. https://docs.python.org/3/library/logging.html#filter-objects
  # "A filter initialized with 'A.B' will allow events logged by loggers 'A.B', 'A.B.C', 'A.B.C.D', 'A.B.D' etc.,
  # but not 'A.BB', 'B.A.B' etc. If initialized with the empty string, all events are passed."
  # Filters can be attached to loggers as well as handlers.
  allow_foo:  # filter id
    # Only allow log records issued by a logger with name "foo".
    # Although loggers can be arbitrarily named, it is customary for libraries to use loggers with names
    # matching the module name, i.e. `logger = logging.getLogger(__name__)`. Thus, this logger
    # would only include log records for package `foo`, including all of `foo`'s sub-modules.
    name: "foo"
  allow_logging_control:
    name: "logging_control"
handlers:
  # 'class' must be specified for all handlers.
  h1: # This is an id
    # configuration of handler with id 'h1' goes here:
    formatter: brief
    class: logging.StreamHandler
    stream: ext://sys.stdout
  h2: # This is another id
    # configuration of handler with id 'h2' goes here:
    formatter: precise
    class: logging.StreamHandler
  console:
    # This handler will print logging records to stdout (using the "brief" formatter):
    class: logging.StreamHandler
    formatter: brief
    level: DEBUG
    filters: [allow_foo, allow_logging_control]  # Messages has to pass ALL filters to be emitted.
    stream: ext://sys.stdout
  file:
    # This handler will print logging records to a file, rotating the file if it is larger than 1024 bytes:
    class: logging.handlers.RotatingFileHandler
    formatter: precise
    filename: logconfig_example_test.log
    maxBytes: 1024
    backupCount: 3
loggers:
  # Set up loggers with specific names (typically corresponding to a particular module or package):
  foo.bar.baz:
    # other configuration for logger 'foo.bar.baz'
    handlers: [h1, h2]
    propagate: false  # Do not propagate log records to foo.bar or any other ancestor.
  simpleExample:
    level: DEBUG
    handlers: [console]
    propagate: no
root:
  # Configure the root logger:
  handlers: [file, console]
  level: INFO