import inspect
import logging
from contextlib import ExitStack
from enum import Enum
from typing import (
TYPE_CHECKING,
Callable,
Iterator,
List,
NamedTuple,
Optional,
Sequence,
Union,
cast,
)
import pendulum
from typing_extensions import TypeGuard
import dagster._check as check
from dagster._annotations import public
from dagster._core.definitions.instigation_logger import InstigationLogger
from dagster._core.errors import (
DagsterInvalidDefinitionError,
DagsterInvalidInvocationError,
DagsterInvalidSubsetError,
DagsterInvariantViolationError,
)
from dagster._core.instance import DagsterInstance
from dagster._core.instance.ref import InstanceRef
from dagster._serdes import whitelist_for_serdes
from ..decorator_utils import get_function_params
from .asset_selection import AssetSelection
from .graph_definition import GraphDefinition
from .mode import DEFAULT_MODE_NAME
from .pipeline_definition import PipelineDefinition
from .run_request import PipelineRunReaction, RunRequest, SkipReason
from .target import DirectTarget, ExecutableDefinition, RepoRelativeTarget
from .unresolved_asset_job_definition import UnresolvedAssetJobDefinition
from .utils import check_valid_name
if TYPE_CHECKING:
from dagster._core.definitions.repository_definition import RepositoryDefinition
@whitelist_for_serdes
class DefaultSensorStatus(Enum):
RUNNING = "RUNNING"
STOPPED = "STOPPED"
DEFAULT_SENSOR_DAEMON_INTERVAL = 30
[docs]class SensorEvaluationContext:
"""The context object available as the argument to the evaluation function of a :py:class:`dagster.SensorDefinition`.
Users should not instantiate this object directly. To construct a
`SensorEvaluationContext` for testing purposes, use :py:func:`dagster.
build_sensor_context`.
Attributes:
instance_ref (Optional[InstanceRef]): The serialized instance configured to run the schedule
cursor (Optional[str]): The cursor, passed back from the last sensor evaluation via
the cursor attribute of SkipReason and RunRequest
last_completion_time (float): DEPRECATED The last time that the sensor was evaluated (UTC).
last_run_key (str): DEPRECATED The run key of the RunRequest most recently created by this
sensor. Use the preferred `cursor` attribute instead.
repository_name (Optional[str]): The name of the repository that the sensor belongs to.
instance (Optional[DagsterInstance]): The deserialized instance can also be passed in
directly (primarily useful in testing contexts).
Example:
.. code-block:: python
from dagster import sensor, SensorEvaluationContext
@sensor
def the_sensor(context: SensorEvaluationContext):
...
"""
def __init__(
self,
instance_ref: Optional[InstanceRef],
last_completion_time: Optional[float],
last_run_key: Optional[str],
cursor: Optional[str],
repository_name: Optional[str],
repository_def: Optional["RepositoryDefinition"] = None,
instance: Optional[DagsterInstance] = None,
sensor_name: Optional[str] = None,
):
self._exit_stack = ExitStack()
self._instance_ref = check.opt_inst_param(instance_ref, "instance_ref", InstanceRef)
self._last_completion_time = check.opt_float_param(
last_completion_time, "last_completion_time"
)
self._last_run_key = check.opt_str_param(last_run_key, "last_run_key")
self._cursor = check.opt_str_param(cursor, "cursor")
self._repository_name = check.opt_str_param(repository_name, "repository_name")
self._repository_def = repository_def
self._instance = check.opt_inst_param(instance, "instance", DagsterInstance)
self._sensor_name = sensor_name
self._log_key = (
[
repository_name,
sensor_name,
pendulum.now("UTC").strftime("%Y%m%d_%H%M%S"),
]
if repository_name and sensor_name
else None
)
self._logger: Optional[InstigationLogger] = None
def __enter__(self):
return self
def __exit__(self, _exception_type, _exception_value, _traceback):
self._exit_stack.close()
self._logger = None
@public # type: ignore
@property
def instance(self) -> DagsterInstance:
# self._instance_ref should only ever be None when this SensorEvaluationContext was
# constructed under test.
if not self._instance:
if not self._instance_ref:
raise DagsterInvariantViolationError(
"Attempted to initialize dagster instance, but no instance reference was"
" provided."
)
self._instance = self._exit_stack.enter_context(
DagsterInstance.from_ref(self._instance_ref)
)
return cast(DagsterInstance, self._instance)
@property
def instance_ref(self) -> Optional[InstanceRef]:
return self._instance_ref
@public # type: ignore
@property
def last_completion_time(self) -> Optional[float]:
return self._last_completion_time
@public # type: ignore
@property
def last_run_key(self) -> Optional[str]:
return self._last_run_key
@public # type: ignore
@property
def cursor(self) -> Optional[str]:
"""The cursor value for this sensor, which was set in an earlier sensor evaluation."""
return self._cursor
[docs] @public
def update_cursor(self, cursor: Optional[str]) -> None:
"""Updates the cursor value for this sensor, which will be provided on the context for the
next sensor evaluation.
This can be used to keep track of progress and avoid duplicate work across sensor
evaluations.
Args:
cursor (Optional[str]):
"""
self._cursor = check.opt_str_param(cursor, "cursor")
@public # type: ignore
@property
def repository_name(self) -> Optional[str]:
return self._repository_name
@public # type: ignore
@property
def repository_def(self) -> Optional["RepositoryDefinition"]:
return self._repository_def
@property
def log(self) -> logging.Logger:
if self._logger:
return self._logger
if not self._instance_ref:
self._logger = self._exit_stack.enter_context(
InstigationLogger(
self._log_key,
repository_name=self._repository_name,
name=self._sensor_name,
)
)
return cast(logging.Logger, self._logger)
self._logger = self._exit_stack.enter_context(
InstigationLogger(
self._log_key,
self.instance,
repository_name=self._repository_name,
name=self._sensor_name,
)
)
return cast(logging.Logger, self._logger)
def has_captured_logs(self):
return self._logger and self._logger.has_captured_logs()
@property
def log_key(self) -> Optional[List[str]]:
return self._log_key
# Preserve SensorExecutionContext for backcompat so type annotations don't break.
SensorExecutionContext = SensorEvaluationContext
RawSensorEvaluationFunctionReturn = Union[
Iterator[Union[SkipReason, RunRequest]],
Sequence[RunRequest],
SkipReason,
RunRequest,
PipelineRunReaction,
]
RawSensorEvaluationFunction = Union[
Callable[[], RawSensorEvaluationFunctionReturn],
Callable[[SensorEvaluationContext], RawSensorEvaluationFunctionReturn],
]
SensorEvaluationFunction = Callable[
[SensorEvaluationContext], Iterator[Union[SkipReason, RunRequest]]
]
def is_context_provided(
fn: "RawSensorEvaluationFunction",
) -> TypeGuard[Callable[[SensorEvaluationContext], "RawSensorEvaluationFunctionReturn"]]:
return len(get_function_params(fn)) == 1
[docs]class SensorDefinition:
"""Define a sensor that initiates a set of runs based on some external state.
Args:
evaluation_fn (Callable[[SensorEvaluationContext]]): The core evaluation function for the
sensor, which is run at an interval to determine whether a run should be launched or
not. Takes a :py:class:`~dagster.SensorEvaluationContext`.
This function must return a generator, which must yield either a single SkipReason
or one or more RunRequest objects.
name (Optional[str]): The name of the sensor to create. Defaults to name of evaluation_fn
minimum_interval_seconds (Optional[int]): The minimum number of seconds that will elapse
between sensor evaluations.
description (Optional[str]): A human-readable description of the sensor.
job (Optional[GraphDefinition, JobDefinition]): The job to execute when this sensor fires.
jobs (Optional[Sequence[GraphDefinition, JobDefinition]]): (experimental) A list of jobs to execute when this sensor fires.
default_status (DefaultSensorStatus): Whether the sensor starts as running or not. The default
status can be overridden from Dagit or via the GraphQL API.
asset_selection (AssetSelection): (Experimental) an asset selection to launch a run for if
the sensor condition is met. This can be provided instead of specifying a job.
"""
def __init__(
self,
name: Optional[str] = None,
*,
evaluation_fn: Optional[RawSensorEvaluationFunction] = None,
job_name: Optional[str] = None,
minimum_interval_seconds: Optional[int] = None,
description: Optional[str] = None,
job: Optional[ExecutableDefinition] = None,
jobs: Optional[Sequence[ExecutableDefinition]] = None,
default_status: DefaultSensorStatus = DefaultSensorStatus.STOPPED,
asset_selection: Optional[AssetSelection] = None,
):
if evaluation_fn is None:
raise DagsterInvalidDefinitionError("Must provide evaluation_fn to SensorDefinition.")
if (
sum(
[
int(job is not None),
int(jobs is not None),
int(job_name is not None),
int(asset_selection is not None),
]
)
> 1
):
raise DagsterInvalidDefinitionError(
"Attempted to provide more than one of 'job', 'jobs', 'job_name', and "
"'asset_selection' params to SensorDefinition. Must provide only one."
)
jobs = jobs if jobs else [job] if job else None
targets: Optional[List[Union[RepoRelativeTarget, DirectTarget]]] = None
if job_name:
targets = [
RepoRelativeTarget(
pipeline_name=check.str_param(job_name, "job_name"),
mode=DEFAULT_MODE_NAME,
solid_selection=None,
)
]
elif job:
targets = [DirectTarget(job)]
elif jobs:
targets = [DirectTarget(job) for job in jobs]
elif asset_selection:
targets = []
if name:
self._name = check_valid_name(name)
else:
self._name = evaluation_fn.__name__
self._raw_fn: RawSensorEvaluationFunction = check.callable_param(
evaluation_fn, "evaluation_fn"
)
self._evaluation_fn: Union[
SensorEvaluationFunction,
Callable[
[SensorEvaluationContext],
Iterator[Union[SkipReason, RunRequest, PipelineRunReaction]],
],
] = wrap_sensor_evaluation(self._name, evaluation_fn)
self._min_interval = check.opt_int_param(
minimum_interval_seconds, "minimum_interval_seconds", DEFAULT_SENSOR_DAEMON_INTERVAL
)
self._description = check.opt_str_param(description, "description")
self._targets = check.opt_list_param(targets, "targets", (DirectTarget, RepoRelativeTarget))
self._default_status = check.inst_param(
default_status, "default_status", DefaultSensorStatus
)
self._asset_selection = check.opt_inst_param(
asset_selection, "asset_selection", AssetSelection
)
def __call__(self, *args, **kwargs):
if is_context_provided(self._raw_fn):
if len(args) + len(kwargs) == 0:
raise DagsterInvalidInvocationError(
"Sensor evaluation function expected context argument, but no context argument "
"was provided when invoking."
)
if len(args) + len(kwargs) > 1:
raise DagsterInvalidInvocationError(
"Sensor invocation received multiple arguments. Only a first "
"positional context parameter should be provided when invoking."
)
context_param_name = get_function_params(self._raw_fn)[0].name
if args:
context = check.opt_inst_param(args[0], context_param_name, SensorEvaluationContext)
else:
if context_param_name not in kwargs:
raise DagsterInvalidInvocationError(
f"Sensor invocation expected argument '{context_param_name}'."
)
context = check.opt_inst_param(
kwargs[context_param_name], context_param_name, SensorEvaluationContext
)
context = context if context else build_sensor_context()
return self._raw_fn(context)
else:
if len(args) + len(kwargs) > 0:
raise DagsterInvalidInvocationError(
"Sensor decorated function has no arguments, but arguments were provided to "
"invocation."
)
return self._raw_fn() # type: ignore [TypeGuard limitation]
@public # type: ignore
@property
def name(self) -> str:
return self._name
@public # type: ignore
@property
def description(self) -> Optional[str]:
return self._description
@public # type: ignore
@property
def minimum_interval_seconds(self) -> Optional[int]:
return self._min_interval
@property
def targets(self) -> Sequence[Union[DirectTarget, RepoRelativeTarget]]:
return self._targets
@public # type: ignore
@property
def job(self) -> Union[PipelineDefinition, GraphDefinition, UnresolvedAssetJobDefinition]:
if self._targets:
if len(self._targets) == 1 and isinstance(self._targets[0], DirectTarget):
return self._targets[0].target
elif len(self._targets) > 1:
raise DagsterInvalidDefinitionError(
"Job property not available when SensorDefinition has multiple jobs."
)
raise DagsterInvalidDefinitionError("No job was provided to SensorDefinition.")
def evaluate_tick(self, context: "SensorEvaluationContext") -> "SensorExecutionData":
"""Evaluate sensor using the provided context.
Args:
context (SensorEvaluationContext): The context with which to evaluate this sensor.
Returns:
SensorExecutionData: Contains list of run requests, or skip message if present.
"""
context = check.inst_param(context, "context", SensorEvaluationContext)
result = list(self._evaluation_fn(context))
skip_message: Optional[str] = None
run_requests: List[RunRequest]
pipeline_run_reactions: List[PipelineRunReaction]
if not result or result == [None]:
run_requests = []
pipeline_run_reactions = []
skip_message = "Sensor function returned an empty result"
elif len(result) == 1:
item = result[0]
check.inst(item, (SkipReason, RunRequest, PipelineRunReaction))
run_requests = [item] if isinstance(item, RunRequest) else []
pipeline_run_reactions = (
[cast(PipelineRunReaction, item)] if isinstance(item, PipelineRunReaction) else []
)
skip_message = item.skip_message if isinstance(item, SkipReason) else None
else:
check.is_list(result, (SkipReason, RunRequest, PipelineRunReaction))
has_skip = any(map(lambda x: isinstance(x, SkipReason), result))
run_requests = [item for item in result if isinstance(item, RunRequest)]
pipeline_run_reactions = [
item for item in result if isinstance(item, PipelineRunReaction)
]
if has_skip:
if len(run_requests) > 0:
check.failed(
"Expected a single SkipReason or one or more RunRequests: received both "
"RunRequest and SkipReason"
)
elif len(pipeline_run_reactions) > 0:
check.failed(
"Expected a single SkipReason or one or more PipelineRunReaction: "
"received both PipelineRunReaction and SkipReason"
)
else:
check.failed("Expected a single SkipReason: received multiple SkipReasons")
self.check_valid_run_requests(run_requests)
if self._asset_selection:
run_requests = [
*_run_requests_with_base_asset_jobs(run_requests, context, self._asset_selection)
]
return SensorExecutionData(
run_requests,
skip_message,
context.cursor,
pipeline_run_reactions,
captured_log_key=context.log_key if context.has_captured_logs() else None,
)
def has_loadable_targets(self) -> bool:
for target in self._targets:
if isinstance(target, DirectTarget):
return True
return False
def load_targets(
self,
) -> Sequence[Union[PipelineDefinition, GraphDefinition, UnresolvedAssetJobDefinition]]:
targets = []
for target in self._targets:
if isinstance(target, DirectTarget):
targets.append(target.load())
return targets
def check_valid_run_requests(self, run_requests: Sequence[RunRequest]):
has_multiple_targets = len(self._targets) > 1
target_names = [target.pipeline_name for target in self._targets]
if run_requests and not self._targets and not self._asset_selection:
raise Exception(
f"Error in sensor {self._name}: Sensor evaluation function returned a RunRequest "
"for a sensor lacking a specified target (job_name, job, or jobs). Targets "
"can be specified by providing job, jobs, or job_name to the @sensor "
"decorator."
)
for run_request in run_requests:
if run_request.job_name is None and has_multiple_targets:
raise Exception(
f"Error in sensor {self._name}: Sensor returned a RunRequest that did not "
f"specify job_name for the requested run. Expected one of: {target_names}"
)
elif run_request.job_name and run_request.job_name not in target_names:
raise Exception(
f"Error in sensor {self._name}: Sensor returned a RunRequest with job_name "
f"{run_request.job_name}. Expected one of: {target_names}"
)
@property
def _target(self) -> Optional[Union[DirectTarget, RepoRelativeTarget]]:
return self._targets[0] if self._targets else None
@public # type: ignore
@property
def job_name(self) -> Optional[str]:
if len(self._targets) > 1:
raise DagsterInvalidInvocationError(
f"Cannot use `job_name` property for sensor {self.name}, which targets multiple"
" jobs."
)
return self._targets[0].pipeline_name
@public # type: ignore
@property
def default_status(self) -> DefaultSensorStatus:
return self._default_status
@property
def asset_selection(self) -> Optional[AssetSelection]:
return self._asset_selection
@whitelist_for_serdes
class SensorExecutionData(
NamedTuple(
"_SensorExecutionData",
[
("run_requests", Optional[Sequence[RunRequest]]),
("skip_message", Optional[str]),
("cursor", Optional[str]),
("pipeline_run_reactions", Optional[Sequence[PipelineRunReaction]]),
("captured_log_key", Optional[Sequence[str]]),
],
)
):
def __new__(
cls,
run_requests: Optional[Sequence[RunRequest]] = None,
skip_message: Optional[str] = None,
cursor: Optional[str] = None,
pipeline_run_reactions: Optional[Sequence[PipelineRunReaction]] = None,
captured_log_key: Optional[Sequence[str]] = None,
):
check.opt_sequence_param(run_requests, "run_requests", RunRequest)
check.opt_str_param(skip_message, "skip_message")
check.opt_str_param(cursor, "cursor")
check.opt_sequence_param(
pipeline_run_reactions, "pipeline_run_reactions", PipelineRunReaction
)
check.opt_list_param(captured_log_key, "captured_log_key", str)
check.invariant(
not (run_requests and skip_message), "Found both skip data and run request data"
)
return super(SensorExecutionData, cls).__new__(
cls,
run_requests=run_requests,
skip_message=skip_message,
cursor=cursor,
pipeline_run_reactions=pipeline_run_reactions,
captured_log_key=captured_log_key,
)
def wrap_sensor_evaluation(
sensor_name: str,
fn: RawSensorEvaluationFunction,
) -> SensorEvaluationFunction:
def _wrapped_fn(context: SensorEvaluationContext):
if is_context_provided(fn):
result = fn(context)
else:
result = fn() # type: ignore
if inspect.isgenerator(result) or isinstance(result, list):
for item in result:
yield item
elif isinstance(result, (SkipReason, RunRequest)):
yield result
elif result is not None:
raise Exception(
(
"Error in sensor {sensor_name}: Sensor unexpectedly returned output "
"{result} of type {type_}. Should only return SkipReason or "
"RunRequest objects."
).format(sensor_name=sensor_name, result=result, type_=type(result))
)
return _wrapped_fn
[docs]def build_sensor_context(
instance: Optional[DagsterInstance] = None,
cursor: Optional[str] = None,
repository_name: Optional[str] = None,
repository_def: Optional["RepositoryDefinition"] = None,
sensor_name: Optional[str] = None,
) -> SensorEvaluationContext:
"""Builds sensor execution context using the provided parameters.
This function can be used to provide a context to the invocation of a sensor definition.If
provided, the dagster instance must be persistent; DagsterInstance.ephemeral() will result in an
error.
Args:
instance (Optional[DagsterInstance]): The dagster instance configured to run the sensor.
cursor (Optional[str]): A cursor value to provide to the evaluation of the sensor.
repository_name (Optional[str]): The name of the repository that the sensor belongs to.
repository_def (Optional[RepositoryDefinition]): The repository that the sensor belongs to.
Examples:
.. code-block:: python
context = build_sensor_context()
my_sensor(context)
"""
check.opt_inst_param(instance, "instance", DagsterInstance)
check.opt_str_param(cursor, "cursor")
check.opt_str_param(repository_name, "repository_name")
return SensorEvaluationContext(
instance_ref=None,
last_completion_time=None,
last_run_key=None,
cursor=cursor,
repository_name=repository_name,
instance=instance,
repository_def=repository_def,
sensor_name=sensor_name,
)
def _run_requests_with_base_asset_jobs(
run_requests, context, outer_asset_selection
) -> Sequence[RunRequest]:
"""
For sensors that target asset selections instead of jobs, finds the corresponding base asset
for a selected set of assets.
"""
asset_graph = context.repository_def.asset_graph
result = []
for run_request in run_requests:
if run_request.asset_selection:
asset_keys = run_request.asset_selection
unexpected_asset_keys = (
AssetSelection.keys(*asset_keys) - outer_asset_selection
).resolve(asset_graph)
if unexpected_asset_keys:
raise DagsterInvalidSubsetError(
"RunRequest includes asset keys that are not part of sensor's asset_selection:"
f" {unexpected_asset_keys}"
)
else:
asset_keys = outer_asset_selection.resolve(asset_graph)
base_job = context.repository_def.get_base_job_for_assets(asset_keys)
result.append(
run_request.with_replaced_attrs(
job_name=base_job.name, asset_selection=list(asset_keys)
)
)
return result