[AIRFLOW-5869] BugFix: Creating DagRuns fails for Deserialized tasks …

[kaxil]

…with no start_date

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Jira

• https://issues.apache.org/jira/browse/AIRFLOW-5869

Description

• Here are some details about my PR, including screenshots of any UI changes:
  Deserialized operators do not always have start_date set.

That, for instance, breaks triggering dags.

See the code from DAG.create_dagrun():

        run = DagRun(...)
        session.add(run)
        session.commit()

        run.dag = self
        run.verify_integrity(session=session) # this validation fails because run assumes that all operators have start_date set
        run.refresh_from_db()

One of the optimisation (https://github.com/coufon/airflow/commit/b5ee858f44f55818c589cf2c8bf3866fa5d50e30) we did as part of DAG Serialization was to not store dates in tasks if they have a matching date (start_date or end_date) in DAG. Unfortunately, when triggering DAG containing such tasks, it fails on DagRun.run.verify_integrity.

The fix is to add the start_date when deserializing the operator.

Tests

• My PR adds the following unit tests OR does not need testing for this extremely good reason:

• test_deserialization_start_date
• test_deserialization_end_date

Commits

• My commits all reference Jira issues in their subject lines, and I have squashed multiple commits if they address the same issue. In addition, my commits follow the guidelines from "How to write a good git commit message":
  1. Subject is separated from body by a blank line
  2. Subject is limited to 50 characters (not including Jira issue reference)
  3. Subject does not end with a period
  4. Subject uses the imperative mood ("add", not "adding")
  5. Body wraps at 72 characters
  6. Body explains "what" and "why", not "how"

Documentation

• In case of new functionality, my PR adds documentation that describes how to use it.
  • All the public functions and the classes in the PR contain docstrings that explain what it does
  • If you implement backwards incompatible changes, please leave a note in the Updating.md so we can assign it to a appropriate release

[codecov-io]

Codecov Report

Merging #6519 into master will decrease coverage by 0.43%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #6519      +/-   ##
==========================================
- Coverage   83.98%   83.54%   -0.44%     
==========================================
  Files         635      635              
  Lines       36722    36725       +3     
==========================================
- Hits        30840    30683     -157     
- Misses       5882     6042     +160

Impacted Files	Coverage Δ
airflow/serialization/serialized_dag.py	96% <100%> (+0.16%)	⬆️
airflow/kubernetes/volume_mount.py	44.44% <0%> (-55.56%)	⬇️
airflow/executors/sequential_executor.py	47.61% <0%> (-52.39%)	⬇️
airflow/kubernetes/volume.py	52.94% <0%> (-47.06%)	⬇️
airflow/kubernetes/pod_launcher.py	45.25% <0%> (-46.72%)	⬇️
airflow/kubernetes/kube_client.py	33.33% <0%> (-41.67%)	⬇️
...rflow/contrib/operators/kubernetes_pod_operator.py	70.14% <0%> (-28.36%)	⬇️
airflow/utils/log/colored_log.py	81.81% <0%> (-11.37%)	⬇️
airflow/utils/sqlalchemy.py	86.44% <0%> (-6.78%)	⬇️
airflow/executors/__init__.py	63.26% <0%> (-4.09%)	⬇️
... and 4 more

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[potiuk]

Just make sure description fits in 80 chars when merging.