Mention context variables and logging

docs/apache-airflow/concepts/taskflow.rst

@@ -63,6 +63,23 @@ You can also use a plain value or variable to call a TaskFlow function - for exa
 
 If you want to learn more about using TaskFlow, you should consult :doc:`the TaskFlow tutorial </tutorial_taskflow_api>`.
 
+Context
+-------
+
+When running your callable, Airflow will pass a set of keyword arguments that can be used in your function. This set of kwargs correspond exactly to the :ref:`context variables<templates:variables>` you can use in your Jinja templates.
+
+For this to work, you need to define ``**kwargs`` in your function header, or you can add directly the keyword arguments you would like to get such as ``ti=None`` to have the task instance passed.
+
+Logging
+-------
+
+To use logging from your task functions, simply import and use Python's logging system:
+
+.. code-block:: python
+
+   logger = logging.getlogger("airflow.task")
+
+Every logging line created this way will be recorded in the task log.
 
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