API: Trackers

This page documents the available failure tracking strategies. Trackers are responsible for inspecting exceptions to determine if they should be counted as a failure.

For a high-level guide on choosing a tracker, see the Trackers Component Guide.

---

fluxgate.trackers.All

Bases: TrackerBase

Tracker that matches all exceptions.

Always returns true for any exception, tracking all failures.

Examples:

>>> # Track all exceptions
>>> tracker = All()
>>>
>>> # Track all except ValueError
>>> tracker = All() & ~TypeOf(ValueError)

Note

This is the default behavior when you want to track all exceptions.

__call__

__call__(_exception: Exception) -> bool

Source code in fluxgate/trackers.py

def __call__(self, _exception: Exception) -> bool:
    return True

fluxgate.trackers.TypeOf

TypeOf(*types: type[Exception])

Bases: TrackerBase

Tracker that matches exceptions by type.

Returns true if the exception is an instance of any of the specified types.

Examples:

>>> # Track connection and timeout errors
>>> tracker = TypeOf(ConnectionError, TimeoutError)
>>>
>>> # Combine with OR
>>> tracker = TypeOf(ValueError) | TypeOf(TypeError)

Parameters:

Name	Type	Description	Default
*types	type[Exception]	Exception types to track as failures	()

Raises:

Type	Description
ValueError	If no exception types are provided

Source code in fluxgate/trackers.py

def __init__(self, *types: type[Exception]) -> None:
    if not types:
        raise ValueError("At least one exception type is required")
    self._types = types

__call__

__call__(exception: Exception) -> bool

Source code in fluxgate/trackers.py

def __call__(self, exception: Exception) -> bool:
    return isinstance(exception, self._types)

fluxgate.trackers.Custom

Custom(func: Callable[[Exception], bool])

Bases: TrackerBase

Tracker with custom exception matching logic.

Allows arbitrary logic to determine if an exception should be tracked.

Examples:

>>> # Track only 503 errors from httpx
>>> def is_503(e):
...     return isinstance(e, httpx.HTTPStatusError) and e.response.status_code == 503
>>>
>>> tracker = Custom(is_503)

Parameters:

Name	Type	Description	Default
func	Callable[[Exception], bool]	Function that takes an exception and returns bool	required

Source code in fluxgate/trackers.py

def __init__(self, func: Callable[[Exception], bool]) -> None:
    self._func = func

__call__

__call__(exception: Exception) -> bool

Source code in fluxgate/trackers.py

def __call__(self, exception: Exception) -> bool:
    return self._func(exception)