feat(serialization): implement truncation logic for rendered values

[imrichardwu]

This pull request create truncate_rendered_value helper into the shared library so it can be used consistently across Airflow core and the task SDK without crossing package boundaries.

Truncation logic changes

• Added a new shared package apache-airflow-shared-template-rendering containing truncate_rendered_value along with exported constants TRUNCATE_PREFIX, TRUNCATE_SUFFIX, and TRUNCATE_MIN_CONTENT_LENGTH.
• Updated airflow-core and task-sdk to import from the shared module, removing the cross-boundary import of airflow.utils.helpers in task_runner.py.

Tests

• Added unit tests in shared/template_rendering/tests/ to validate truncation behavior and exact output using the exported constants.
• Updated test_helpers.py and test_renderedtifields.py to use the shared constants instead of duplicating literal strings, and to build expected values from truncate_rendered_value directly rather than the higher-level serialize_template_field.
• Fixed a self-fulfilling assertion in the task SDK truncation+masking test to explicitly verify that env_vars is truncated with the correct prefix/suffix and secrets are redacted.

Closes: #59877

---

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• Used ChatGPT to help create and edit my test cases that were mentioned by a reviewer in a closed pr.

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[SameerMesiah97]

I think this needs some refactoring. The current implementation looks functional but it is not very clear. I think the algorithm should be as follows:

1. If max_length <= 0, return ""

2. Build the truncation message once and, if max_length is smaller than its length, return it immediately.

3. Determine the quoting strategy and compute the formatting overhead (prefix + quotes + suffix) and calculate available space.

4. If available space is less than MIN_CONTENT_LENGTH, return the truncation message only.

5. Otherwise slice the content to fit and construct the final string and ensure the result does not exceed max_length, trimming it if necessary.

Currently, I think you are mixing 3, 4 and 5 when they should each be in disparate blocks of code. And this is resulting in needless duplication.

Also, I was just wondering why this has to be duplicated across 2 files? Perhaps, a maintainer/committer could weigh in on this but is it possible to have this in airflow.utils.helpers instead?

[imrichardwu]

I think this needs some refactoring. The current implementation looks functional but it is not very clear. I think the algorithm should be as follows:

1. If max_length <= 0, return ""
2. Build the truncation message once and, if max_length is smaller than its length, return it immediately.
3. Determine the quoting strategy and compute the formatting overhead (prefix + quotes + suffix) and calculate available space.
4. If available space is less than MIN_CONTENT_LENGTH, return the truncation message only.
5. Otherwise slice the content to fit and construct the final string and ensure the result does not exceed max_length, trimming it if necessary.

Currently, I think you are mixing 3, 4 and 5 when they should each be in disparate blocks of code. And this is resulting in needless duplication.

Also, I was just wondering why this has to be duplicated across 2 files? Perhaps, a maintainer/committer could weigh in on this but is it possible to have this in airflow.utils.helpers instead?

I implemented all your feedback and would love for you to review my pr again!

[pierrejeambrun]

Looks good overall but would love another pair of eyes.

A couple of suggestions.

[Copilot]

Pull request overview

Introduces a shared truncate_rendered_value helper to standardize truncation of rendered template fields across Airflow core and the task SDK, and updates serialization/task-runner code paths to use it.

Changes:

• Added shared truncate_rendered_value utility (new shared package) and wired it into core + task SDK serialization.
• Updated tests to cover truncation edge cases and adjusted existing assertions to accommodate the new behavior.
• Registered the new shared package in workspace/build configuration for core and task SDK.

Reviewed changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
task-sdk/tests/task_sdk/execution_time/test_task_runner.py	Loosens rendered-fields assertion by deriving expected data from the mocked call
task-sdk/src/airflow/sdk/execution_time/task_runner.py	Replaces inline truncation formatting with truncate_rendered_value
task-sdk/src/airflow/sdk/_shared/template_rendering	Adds shared-module path link for template rendering utilities
task-sdk/pyproject.toml	Adds build mapping for shared template rendering package
shared/template_rendering/tests/template_rendering/test_truncate_rendered_value.py	Adds unit tests for truncation helper edge cases and exact output
shared/template_rendering/tests/template_rendering/init.py	Initializes shared template_rendering test package
shared/template_rendering/src/airflow_shared/template_rendering/init.py	Implements truncate_rendered_value
shared/template_rendering/pyproject.toml	Defines new shared workspace package metadata/build config
pyproject.toml	Registers new shared package in dev deps + workspace members
airflow-core/tests/unit/serialization/test_helpers.py	Adds unit tests for truncation helper and very-small max length behavior
airflow-core/tests/unit/models/test_renderedtifields.py	Updates expected truncation outputs to use serialize_template_field
airflow-core/src/airflow/utils/helpers.py	Adds module logger
airflow-core/src/airflow/serialization/helpers.py	Uses shared truncate_rendered_value instead of inline truncation
airflow-core/src/airflow/_shared/template_rendering	Adds shared-module path link for template rendering utilities
airflow-core/pyproject.toml	Adds build mapping for shared template rendering package

[Copilot]

Pull request overview

Copilot reviewed 14 out of 14 changed files in this pull request and generated 7 comments.

[pierrejeambrun]

Looks good to me but we need another pair of eyes. @ashb @uranusjr ?

[potiuk]

@uranusjr — Could you please check whether your review feedback on this PR has been addressed? The author appears to have responded to your comments. If the concerns are resolved, please resolve the conversation threads. Thank you!

[potiuk]

@uranusjr — Could you please check whether your review feedback on this PR has been addressed? @imrichardwu appears to have responded to your comments. @imrichardwu, do you believe the reviewer's concerns have been resolved?

If the concerns are resolved, please resolve the conversation threads. Thank you!

[imrichardwu]

@uranusjr — Could you please check whether your review feedback on this PR has been addressed? @imrichardwu appears to have responded to your comments. @imrichardwu, do you believe the reviewer's concerns have been resolved?

If the concerns are resolved, please resolve the conversation threads. Thank you!

Yes

[potiuk]

Merging it regardless. @uranusjr -> please check it retroactively if you stil have concerns.