dstandish commented on a change in pull request #5388: [AIRFLOW-4490]
DagRun.conf returns empty dictionary by default
URL: https://github.com/apache/airflow/pull/5388#discussion_r292144810
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File path: airflow/models/skipmixin.py
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@@ -41,7 +41,7 @@ def skip(self, dag_run, execution_date, tasks, session=None):
task_ids = [d.task_id for d in tasks]
now = timezone.utcnow()
- if dag_run:
+ if dag_run and dag_run.dag_id:
Review comment:
The idea here is that as long as submitting a dag run conf is supported we
should make it easy to use it optionally in templates.
I wanted a template like `{{ dag_run.conf.get('blah') or 'val' }}` to
_always_ work. But sometimes there is no dag run. So in TI context, when
there's no dag run, I added `DagRun()`, which has no dag_id by default. But
the skip mixing alters behavior based on presence of dag run obj in TI context.
Hence the above change you commented on.
This is why I initially preferred the alternative PR
https://github.com/apache/airflow/pull/5387 which adds `dag_run_conf` context
variable instead of messing with `DagRun`. But it seemed a little silly to add
`dag_run_conf` when `dag_run.conf` is right there.
Aside: Why is the skip mixing even checking for DagRun? I don't know.
Probably for testing I'd guess. But skipping doesn't even make sense outside
of the context of a dag run, so 🤷♀.
**_Anyway,_** after further thought, I think it's _not good_ to provide an
empty `DagRun()` for `dag_run` context variable when there is no dag run. It
should just be `None`. And I will update this PR. Then the above template
example would still work whenever there is a DagRun (which is most of the
time). And for contrived situations like repl-testing of your templating you
can manufacture a dag run.
Do you think that `dag_run_conf` is still worth adding as template var
though? So that there can be one variable we can use to safely check for a dag
run conf variable -- no matter whether a dag run exists or whether a conf
exists?
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