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prefect.settings.models.logging

LoggingSettings

Bases: PrefectBaseSettings

Settings for controlling logging behavior

Source code in src/prefect/settings/models/logging.py 
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class LoggingSettings(PrefectBaseSettings):
    """
    Settings for controlling logging behavior
    """

    model_config = _build_settings_config(("logging",))

    level: LogLevel = Field(
        default="INFO",
        description="The default logging level for Prefect loggers.",
    )

    config_path: Optional[Path] = Field(
        default=None,
        description="The path to a custom YAML logging configuration file.",
        validation_alias=AliasChoices(
            AliasPath("config_path"),
            "prefect_logging_config_path",
            "prefect_logging_settings_path",
        ),
    )

    extra_loggers: Annotated[
        Union[str, list[str], None],
        AfterValidator(lambda v: [n.strip() for n in v.split(",")] if v else []),
    ] = Field(
        default=None,
        description="Additional loggers to attach to Prefect logging at runtime.",
    )

    log_prints: bool = Field(
        default=False,
        description="If `True`, `print` statements in flows and tasks will be redirected to the Prefect logger for the given run.",
    )

    colors: bool = Field(
        default=True,
        description="If `True`, use colors in CLI output. If `False`, output will not include colors codes.",
    )

    markup: bool = Field(
        default=False,
        description="""
        Whether to interpret strings wrapped in square brackets as a style.
        This allows styles to be conveniently added to log messages, e.g.
        `[red]This is a red message.[/red]`. However, the downside is, if enabled,
        strings that contain square brackets may be inaccurately interpreted and
        lead to incomplete output, e.g.
        `[red]This is a red message.[/red]` may be interpreted as
        `[red]This is a red message.[/red]`.
        """,
    )

    to_api: LoggingToAPISettings = Field(
        default_factory=LoggingToAPISettings,
        description="Settings for controlling logging to the API",
    )

LoggingToAPISettings

Bases: PrefectBaseSettings

Settings for controlling logging to the API

Source code in src/prefect/settings/models/logging.py 
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class LoggingToAPISettings(PrefectBaseSettings):
    """
    Settings for controlling logging to the API
    """

    model_config = _build_settings_config(("logging", "to_api"))

    enabled: bool = Field(
        default=True,
        description="If `True`, logs will be sent to the API.",
    )

    batch_interval: float = Field(
        default=2.0,
        description="The number of seconds between batched writes of logs to the API.",
    )

    batch_size: int = Field(
        default=4_000_000,
        description="The number of logs to batch before sending to the API.",
    )

    max_log_size: int = Field(
        default=1_000_000,
        description="The maximum size in bytes for a single log.",
    )

    when_missing_flow: Literal["warn", "error", "ignore"] = Field(
        default="warn",
        description="""
        Controls the behavior when loggers attempt to send logs to the API handler from outside of a flow.

        All logs sent to the API must be associated with a flow run. The API log handler can
        only be used outside of a flow by manually providing a flow run identifier. Logs
        that are not associated with a flow run will not be sent to the API. This setting can
        be used to determine if a warning or error is displayed when the identifier is missing.

        The following options are available:

        - "warn": Log a warning message.
        - "error": Raise an error.
        - "ignore": Do not log a warning message or raise an error.
        """,
    )

    @model_validator(mode="after")
    def emit_warnings(self) -> Self:
        """Emits warnings for misconfiguration of logging settings."""
        values = self.model_dump()
        values = max_log_size_smaller_than_batch_size(values)
        return self

emit_warnings()

Emits warnings for misconfiguration of logging settings.

Source code in src/prefect/settings/models/logging.py 
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@model_validator(mode="after")
def emit_warnings(self) -> Self:
    """Emits warnings for misconfiguration of logging settings."""
    values = self.model_dump()
    values = max_log_size_smaller_than_batch_size(values)
    return self

max_log_size_smaller_than_batch_size(values)

Validator for settings asserting the batch size and match log size are compatible

Source code in src/prefect/settings/models/logging.py 
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def max_log_size_smaller_than_batch_size(values):
    """
    Validator for settings asserting the batch size and match log size are compatible
    """
    if values["batch_size"] < values["max_log_size"]:
        raise ValueError(
            "`PREFECT_LOGGING_TO_API_MAX_LOG_SIZE` cannot be larger than"
            " `PREFECT_LOGGING_TO_API_BATCH_SIZE`"
        )
    return values