Detect template-field logic in operator __init__ in prek check - #70297
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Template fields are rendered after the constructor runs, so any validation or transformation applied to them in __init__ acts on the un-rendered Jinja expression — the bug class behind apache#69813, where SSHRemoteJobOperator validated a templated remote_base_dir at construction time and cleanup then failed for any custom base. The validate-operators-init hook only recognised top-level assignment statements, so validation calls, conditionals and transformations were invisible to it, and sensors, subscripted AwsBaseOperator[...] bases and aws_template_fields(...)-based classes were not covered at all. Pre-existing violations (83 classes) are exempted via a path::Class ratchet file so the rule is enforced on new code immediately; a fixing PR must remove its entry (stale entries fail the hook). Burn-down is tracked at apache#70296.
shahar1
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amoghrajesh,
ashb,
bugraoz93,
gopidesupavan,
jason810496,
jscheffl and
potiuk
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July 23, 2026 12:23
boring-cyborg
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backport-to-v3-3-test
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vincbeck
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Jul 23, 2026
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Backport successfully created: v3-3-testNote: As of Merging PRs targeted for Airflow 3.X In matter of doubt please ask in #release-management Slack channel.
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Human Sumary
Two years ago I've implemented a script for detecting usage of template fields within the constructor (#33786).
It had gone through some improvements, but overall it has always been AST-based - which didn't cover all the cases that these fields could be (ab)used.
But now we have AI - and after letting Claude to improve it, it found plenty of problematic cases nowadays.
As usual, created an exemption list (#70296) and hopefully we could handle everything with the help of the community :)
AI Summary
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Template fields are rendered after the constructor runs, so any validation or transformation applied to them in __init__ acts on the un-rendered Jinja expression — the bug class behind #69813, where SSHRemoteJobOperator validated a templated remote_base_dir at construction time and cleanup then failed for any custom base. The validate-operators-init hook only recognised top-level assignment statements, so validation calls, conditionals and transformations were invisible to it, and sensors, subscripted AwsBaseOperator[...] bases and aws_template_fields(...)-based classes were not covered at all.Pre-existing violations (83 classes) are exempted via a path::Class ratchet file so the rule is enforced on new code immediately; a fixing PR must remove its entry (stale entries fail the hook). Burn-down is tracked at #70296.
Was generative AI tooling used to co-author this PR?
{pr_number}.significant.rst, in airflow-core/newsfragments. You can add this file in a follow-up commit after the PR is created so you know the PR number.