airflow-core/docs/templates-ref.rst
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.. _templates-ref:
concepts:jinja-templating section)
Asset-triggered DAGsAsset-triggered Dags in Apache Airflow 3 differ from time-based Dags in the template context they provide.
Asset-triggered Dags do not have a logical date, and therefore do not provide
time-based context variables such as logical_date, ds, ds_nodash,
or values derived from them.
For asset-triggered Dags, information related to the triggering run can be
accessed via dag_run. For example, dag_run.run_id can be used to
uniquely identify a Dag run triggered by an asset event.
.. versionadded:: 3.0.0
The variables listed on this page are provided via Airflow's execution-time context.
When using the Task SDK, the same execution-time context is also available programmatically via the :class:airflow.sdk.Context object.
The following come for free out of the box with Airflow.
Additional custom macros can be added globally through :doc:administration-and-deployment/plugins, or at a Dag level through the
DAG.user_defined_macros argument.
.. _templates:variables:
The Airflow engine passes a few variables by default that are accessible in all templates
=========================================== ===================== ===================================================================
Variable Type Description
=========================================== ===================== ===================================================================
{{ data_interval_start }} pendulum.DateTime_ Start of the data interval. Added in version 2.2.
{{ data_interval_end }} pendulum.DateTime_ End of the data interval. Added in version 2.2.
{{ logical_date }} pendulum.DateTime_ | A date-time that logically identifies the current Dag run. This value does not contain any semantics, but is simply a value for identification.
| Use data_interval_start and data_interval_end instead if you want a value that has real-world semantics,
| such as to get a slice of rows from the database based on timestamps.
{{ exception }} None | str | | Error occurred while running task instance.
Exception |
KeyboardInterrupt |
{{ prev_data_interval_start_success }} pendulum.DateTime_ | Start of the data interval of the prior successful :class:~airflow.models.dagrun.DagRun.
| None | Added in version 2.2.
{{ prev_data_interval_end_success }} pendulum.DateTime_ | End of the data interval of the prior successful :class:~airflow.models.dagrun.DagRun.
| None | Added in version 2.2.
{{ prev_start_date_success }} pendulum.DateTime_ Start date from prior successful :class:~airflow.models.dagrun.DagRun (if available).
| None
{{ prev_end_date_success }} pendulum.DateTime_ End date from prior successful :class:~airflow.models.dagrun.DagRun (if available).
| None
{{ inlets }} list List of inlets declared on the task.
{{ inlet_events }} dict[str, ...] Access past events of inlet assets. See :doc:Assets <authoring-and-scheduling/asset-scheduling>. Added in version 2.10.
{{ outlets }} list List of outlets declared on the task.
{{ outlet_events }} dict[str, ...] | Accessors to attach information to asset events that will be emitted by the current task.
| See :doc:Assets <authoring-and-scheduling/asset-scheduling>. Added in version 2.10.
{{ dag }} DAG The currently running :class:~airflow.models.dag.DAG. You can read more about Dags in :doc:Dags <core-concepts/dags>.
{{ task }} BaseOperator | The currently running :class:~airflow.models.baseoperator.BaseOperator. You can read more about Tasks in :doc:core-concepts/operators
{{ task_reschedule_count }} int How many times current task has been rescheduled. Relevant to mode="reschedule" sensors.
{{ macros }} | A reference to the macros package. See Macros_ below.
{{ task_instance }} TaskInstance The currently running :class:~airflow.models.taskinstance.TaskInstance.
{{ ti }} TaskInstance Same as {{ task_instance }}.
{{ params }} dict[str, Any] | The user-defined params. This can be overridden by the mapping
| passed to trigger_dag -c if dag_run_conf_overrides_params
| is enabled in airflow.cfg.
{{ var.value }} Airflow variables. See Airflow Variables in Templates_ below.
{{ var.json }} Airflow variables. See Airflow Variables in Templates_ below.
{{ conn }} Airflow connections. See Airflow Connections in Templates_ below.
{{ task_instance_key_str }} str | A human-readable key to the task instance.
|
| For time-based DAGs, the format is
| {dag_id}__{task_id}__{ds_nodash}.
|
| For asset-triggered DAGs, the format uses the DAG run identifier instead:
| {dag_id}__{task_id}__{dag_run.run_id}.
{{ run_id }} str The currently running :class:~airflow.models.dagrun.DagRun run ID.
{{ dag_run }} DagRun The currently running :class:~airflow.models.dagrun.DagRun.
{{ test_mode }} bool Whether the task instance was run by the airflow test CLI.
{{ map_index_template }} None | str Template used to render the expanded task instance of a mapped task. Setting this value will be reflected in the rendered result.
{{ expanded_ti_count }} int | None | Number of task instances that a mapped task was expanded into. If
| the current task is not mapped, this should be None.
| Added in version 2.5.
{{ triggering_asset_events }} dict[str, | If in an Asset Scheduled Dag, a map of Asset URI to a list of triggering :class:~airflow.models.asset.AssetEvent
list[AssetEvent]] | (there may be more than one, if there are multiple Assets with different frequencies).
| Read more here :doc:Assets <authoring-and-scheduling/asset-scheduling>.
| Added in version 2.4.
=========================================== ===================== ===================================================================
The following are only available when the DagRun has a logical_date
=========================================== ===================== ===================================================================
Variable Type Description
=========================================== ===================== ===================================================================
{{ ds }} str | The Dag run's logical date as YYYY-MM-DD.
| Same as {{ logical_date | ds }}.
{{ ds_nodash }} str Same as {{ logical_date | ds_nodash }}.
{{ ts }} str | Same as {{ logical_date | ts }}.
| Example: 2018-01-01T00:00:00+00:00.
{{ ts_nodash_with_tz }} str | Same as {{ logical_date | ts_nodash_with_tz }}.
| Example: 20180101T000000+0000.
{{ ts_nodash }} str | Same as {{ logical_date | ts_nodash }}.
| Example: 20180101T000000.
=========================================== ===================== ===================================================================
.. note::
The Dag run's logical date, and values derived from it, such as ``ds`` and
``ts``, **should not** be considered unique in a Dag. Use ``run_id`` instead.
While @task decorated tasks don't support rendering jinja templates passed as arguments,
all of the variables listed above can be accessed directly from tasks. The following code block
is an example of accessing a task_instance object from its task:
.. include:: /../../devel-common/src/docs/shared/template-examples/taskflow.rst
Note that you can access the object's attributes and methods with simple
dot notation. Here are some examples of what is possible:
{{ task.owner }}, {{ task.task_id }}, {{ ti.hostname }}, ...
Refer to the models documentation for more information on the objects'
attributes and methods.
The var template variable allows you to access Airflow Variables.
You can access them as either plain-text or JSON. If you use JSON, you are
also able to walk nested structures, such as dictionaries like:
{{ var.json.my_dict_var.key1 }}.
It is also possible to fetch a variable by string if needed (for example your variable key contains dots) with
{{ var.value.get('my.var', 'fallback') }} or
{{ var.json.get('my.dict.var', {'key1': 'val1'}) }}. Defaults can be
supplied in case the variable does not exist.
Similarly, Airflow Connections data can be accessed via the conn template variable. For example, you could use expressions in your templates like {{ conn.my_conn_id.login }},
{{ conn.my_conn_id.password }}, etc.
Just like with var it's possible to fetch a connection by string (e.g. {{ conn.get('my_conn_id_'+index).host }}
) or provide defaults (e.g {{ conn.get('my_conn_id', {"host": "host1", "login": "user1"}).host }}).
Additionally, the extras field of a connection can be fetched as a Python Dictionary with the extra_dejson field, e.g.
conn.my_aws_conn_id.extra_dejson.region_name would fetch region_name out of extras.
This way, defaults in extras can be provided as well (e.g. {{ conn.my_aws_conn_id.extra_dejson.get('region_name', 'Europe (Frankfurt)') }}).
Airflow defines some Jinja filters that can be used to format values.
For example, using {{ logical_date | ds }} will output the logical_date in the YYYY-MM-DD format.
===================== ============ ==================================================================
Filter Operates on Description
===================== ============ ==================================================================
ds datetime Format the datetime as YYYY-MM-DD
ds_nodash datetime Format the datetime as YYYYMMDD
ts datetime Same as .isoformat(), Example: 2018-01-01T00:00:00+00:00
ts_nodash datetime Same as ts filter without -, : or TimeZone info.
Example: 20180101T000000
ts_nodash_with_tz datetime As ts filter without - or :. Example
20180101T000000+0000
===================== ============ ==================================================================
.. _templates:macros:
Macros are a way to expose objects to your templates and live under the
macros namespace in your templates.
A few commonly used libraries and methods are made available.
================================= ========================================================================================================================================================================
Variable Description
================================= ========================================================================================================================================================================
macros.datetime The standard lib's :class:datetime.datetime.
Note: utcnow() is deprecated in Python 3.12+; use now(macros.dateutil.tz.UTC) instead.
macros.timedelta The standard lib's :class:datetime.timedelta
macros.dateutil A reference to the dateutil package
macros.time The standard lib's :mod:time
macros.uuid The standard lib's :mod:uuid
macros.random The standard lib's :class:random.random
================================= ========================================================================================================================================================================
Some Airflow specific macros are also defined:
.. automodule:: airflow.sdk.execution_time.macros :members:
.. _pendulum.DateTime: https://pendulum.eustace.io/docs/#introduction