Airflow - 2.7.1

Significant Changes

CronTriggerTimetable is now less aggressive when trying to skip a run (#33404)

When setting catchup=False, CronTriggerTimetable no longer skips a run if
the scheduler does not query the timetable immediately after the previous run
has been triggered.

This should not affect scheduling in most cases, but can change the behaviour if
a DAG is paused-unpaused to manually skip a run. Previously, the timetable (with
catchup=False) would only start a run after a DAG is unpaused, but with this
change, the scheduler would try to look at little bit back to schedule the
previous run that covers a part of the period when the DAG was paused. This
means you will need to keep a DAG paused longer (namely, for the entire cron
period to pass) to really skip a run.

Note that this is also the behaviour exhibited by various other cron-based
scheduling tools, such as anacron.

conf.set() becomes case insensitive to match conf.get() behavior (#33452)

Also, conf.get() will now break if used with non-string parameters.

conf.set(section, key, value) used to be case sensitive, i.e. conf.set("SECTION", "KEY", value)
and conf.set("section", "key", value) were stored as two distinct configurations.
This was inconsistent with the behavior of conf.get(section, key), which was always converting the section and key to lower case.

As a result, configuration options set with upper case characters in the section or key were unreachable.
That's why we are now converting section and key to lower case in conf.set too.

We also changed a bit the behavior of conf.get(). It used to allow objects that are not strings in the section or key.
Doing this will now result in an exception. For instance, conf.get("section", 123) needs to be replaced with conf.get("section", "123").

Bug Fixes

• Ensure that tasks wait for running indirect setup (#33903)
• Respect "soft_fail" for core async sensors (#33403)
• Differentiate 0 and unset as a default param values (#33965)
• Raise 404 from Variable PATCH API if variable is not found (#33885)
• Fix MappedTaskGroup tasks not respecting upstream dependency (#33732)
• Add limit 1 if required first value from query result (#33672)
• Fix UI DAG counts including deleted DAGs (#33778)
• Fix cleaning zombie RESTARTING tasks (#33706)
• SECURITY_MANAGER_CLASS should be a reference to class, not a string (#33690)
• Add back get_url_for_login in security manager (#33660)
• Fix 2.7.0 db migration job errors (#33652)
• Set context inside templates (#33645)
• Treat dag-defined access_control as authoritative if defined (#33632)
• Bind engine before attempting to drop archive tables (#33622)
• Add a fallback in case no first name and last name are set (#33617)
• Sort data before groupby in TIS duration calculation (#33535)
• Stop adding values to rendered templates UI when there is no dagrun (#33516)
• Set strict to True when parsing dates in webserver views (#33512)
• Use dialect.name in custom SA types (#33503)
• Do not return ongoing dagrun when a end_date is less than utcnow (#33488)
• Fix a bug in formatDuration method (#33486)
• Make conf.set case insensitive (#33452)
• Allow timetable to slightly miss catchup cutoff (#33404)
• Respect soft_fail argument when poke is called (#33401)
• Create a new method used to resume the task in order to implement specific logic for operators (#33424)
• Fix DagFileProcessor interfering with dags outside its processor_subdir (#33357)
• Remove the unnecessary <br> text in Provider's view (#33326)
• Respect soft_fail argument when ExternalTaskSensor runs in deferrable mode (#33196)
• Fix handling of default value and serialization of Param class (#33141)
• Check if the dynamically-added index is in the table schema before adding (#32731)
• Fix rendering the mapped parameters when using expand_kwargs method (#32272)
• Fix dependencies for celery and opentelemetry for Python 3.8 (#33579)

Misc/Internal

• Bring back Pydantic 1 compatibility (#34081, #33998)
• Use a trimmed version of README.md for PyPI (#33637)
• Upgrade to Pydantic 2 (#33956)
• Reorganize devel_only extra in Airflow's setup.py (#33907)
• Bumping FAB to 4.3.4 in order to fix issues with filters (#33931)
• Add minimum requirement for sqlalchemy to 1.4.24 (#33892)
• Update version_added field for configs in config file (#33509)
• Replace OrderedDict with plain dict (#33508)
• Consolidate import and usage of itertools (#33479)
• Static check fixes (#33462)
• Import utc from datetime and normalize its import (#33450)
• D401 Support (#33352, #33339, #33337, #33336, #33335, #33333, #33338)
• Fix some missing type hints (#33334)
• D205 Support - Stragglers (#33301, #33298, #33297)
• Refactor: Simplify code (#33160, #33270, #33268, #33267, #33266, #33264, #33292, #33453, #33476, #33567,
  #33568, #33480, #33753, #33520, #33623)
• Fix Pydantic warning about orm_mode rename (#33220)
• Add MySQL 8.1 to supported versions. (#33576)
• Remove Pydantic limitation for version < 2 (#33507)

Doc only changes

• Add documentation explaining template_ext (and how to override it) (#33735)
• Explain how users can check if python code is top-level (#34006)
• Clarify that DAG authors can also run code in DAG File Processor (#33920)
• Fix broken link in Modules Management page (#33499)
• Fix secrets backend docs (#33471)
• Fix config description for base_log_folder (#33388)