Templates reference

Variables, macros and filters can be used in templates (see the Jinja Templating section)

The following come for free out of the box with Airflow. Additional custom macros can be added globally through Plugins, or at a DAG level through the DAG.user_defined_macros argument.

Variables

The Airflow engine passes a few variables by default that are accessible in all templates

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.

The following variables are deprecated. They are kept for backward compatibility, but you should convert existing code to use other variables instead.

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.

Airflow Variables in Templates

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 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.

Airflow Connections in Templates

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.

Filters

Airflow defines some Jinja filters that can be used to format values.

For example, using {{ execution_date | ds }} will output the execution_date in the YYYY-MM-DD format.

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.

Some airflow specific macros are also defined:

airflow.macros.datetime_diff_for_humans(dt, since=None)[source]

Return a human-readable/approximate difference between datetimes.

When only one datetime is provided, the comparison will be based on now.

• Parameters

  • dt (Any) – The datetime to display the diff for

  • since (DateTime | None) – When to display the date from. If None then the diff is between dt and now.

airflow.macros.ds_add(ds, days)[source]

Add or subtract days from a YYYY-MM-DD.

• Parameters

  • ds (str) – anchor date in YYYY-MM-DD format to add to

  • days (int) – number of days to add to the ds, you can use negative values

>>> ds_add('2015-01-01', 5)
'2015-01-06'
>>> ds_add('2015-01-06', -5)
'2015-01-01'

airflow.macros.ds_format(ds, input_format, output_format)[source]

Output datetime string in a given format.

• Parameters

  • ds (str) – input string which contains a date

  • input_format (str) – input string format. E.g. %Y-%m-%d

  • output_format (str) – output string format E.g. %Y-%m-%d

>>> ds_format('2015-01-01', "%Y-%m-%d", "%m-%d-%y")
'01-01-15'
>>> ds_format('1/5/2015', "%m/%d/%Y",  "%Y-%m-%d")
'2015-01-05'

airflow.macros.random() → x in the interval [0, 1).