Events: fix anything-but with null values #13268

bentsku · 2025-10-14T17:22:15Z

Motivation

We got a report from a user that when using anything-but with nested suffix, and the target field was missing from the event, we would raise an internal error as we were not handling null value accordingly.

We need to differentiate between 2 kind of null value: missing value (result of event.get()) and user-set null.

If the user is setting the value to null, the default behavior of anything-but works, meaning that it returns true like any string not matching the pattern would.
If the value is missing entirely, then we're not in the "anything but" case, and it returns False.

Changes

add validation for null value in the pattern for anything-but patterns
add lots of test cases around anything-but and its nested conditions with both missing values and user-set null values
fix the behavior to properly take into account null values, and handle them depending on their existence or not

github-actions · 2025-10-14T17:42:19Z

Test Results - Preflight, Unit

22 337 tests ±0 20 587 ✅ ±0 15m 53s ⏱️ +22s
1 suites ±0 1 750 💤 ±0
1 files ±0 0 ❌ ±0

Results for commit d7e2d4b. ± Comparison against base commit 73e4f6c.

♻️ This comment has been updated with latest results.

github-actions · 2025-10-14T17:51:01Z

Test Results (amd64) - Acceptance

7 tests ±0 5 ✅ ±0 3m 23s ⏱️ +2s
1 suites ±0 2 💤 ±0
1 files ±0 0 ❌ ±0

Results for commit d7e2d4b. ± Comparison against base commit 73e4f6c.

♻️ This comment has been updated with latest results.

github-actions · 2025-10-14T17:52:31Z

Test Results - Alternative Providers

406 tests 274 ✅ 4m 8s ⏱️
1 suites 132 💤
1 files 0 ❌

Results for commit d7e2d4b.

♻️ This comment has been updated with latest results.

github-actions · 2025-10-14T18:05:44Z

LocalStack Community integration with Pro

2 files ± 0 2 suites ±0 58m 15s ⏱️ - 1h 1m 11s
2 680 tests - 2 136 2 572 ✅ - 1 907 108 💤 - 229 0 ❌ ±0
2 682 runs - 2 136 2 572 ✅ - 1 907 110 💤 - 229 0 ❌ ±0

Results for commit d7e2d4b. ± Comparison against base commit 73e4f6c.

This pull request removes 2163 and adds 27 tests. Note that renamed tests count towards both.

tests.aws.scenario.bookstore.test_bookstore.TestBookstoreApplication ‑ test_lambda_dynamodb
tests.aws.scenario.bookstore.test_bookstore.TestBookstoreApplication ‑ test_opensearch_crud
tests.aws.scenario.bookstore.test_bookstore.TestBookstoreApplication ‑ test_search_books
tests.aws.scenario.bookstore.test_bookstore.TestBookstoreApplication ‑ test_setup
tests.aws.scenario.kinesis_firehose.test_kinesis_firehose.TestKinesisFirehoseScenario ‑ test_kinesis_firehose_s3
tests.aws.scenario.lambda_destination.test_lambda_destination_scenario.TestLambdaDestinationScenario ‑ test_destination_sns
tests.aws.scenario.lambda_destination.test_lambda_destination_scenario.TestLambdaDestinationScenario ‑ test_infra
tests.aws.scenario.loan_broker.test_loan_broker.TestLoanBrokerScenario ‑ test_prefill_dynamodb_table
tests.aws.scenario.loan_broker.test_loan_broker.TestLoanBrokerScenario ‑ test_stepfunctions_input_recipient_list[step_function_input0-SUCCEEDED]
tests.aws.scenario.loan_broker.test_loan_broker.TestLoanBrokerScenario ‑ test_stepfunctions_input_recipient_list[step_function_input1-SUCCEEDED]
…

tests.aws.services.events.test_events_patterns.TestEventPattern ‑ test_event_pattern[content_anything_but_ignorecase_list_missing_NEG]
tests.aws.services.events.test_events_patterns.TestEventPattern ‑ test_event_pattern[content_anything_but_ignorecase_list_null]
tests.aws.services.events.test_events_patterns.TestEventPattern ‑ test_event_pattern[content_anything_but_ignorecase_missing_NEG]
tests.aws.services.events.test_events_patterns.TestEventPattern ‑ test_event_pattern[content_anything_but_ignorecase_null]
tests.aws.services.events.test_events_patterns.TestEventPattern ‑ test_event_pattern[content_anything_but_string_list_missing_NEG]
tests.aws.services.events.test_events_patterns.TestEventPattern ‑ test_event_pattern[content_anything_but_string_list_null]
tests.aws.services.events.test_events_patterns.TestEventPattern ‑ test_event_pattern[content_anything_but_string_list_null_type_EXC]
tests.aws.services.events.test_events_patterns.TestEventPattern ‑ test_event_pattern[content_anything_but_string_missing_NEG]
tests.aws.services.events.test_events_patterns.TestEventPattern ‑ test_event_pattern[content_anything_but_string_null_type_EXC]
tests.aws.services.events.test_events_patterns.TestEventPattern ‑ test_event_pattern[content_anything_prefix_int_value]
…

♻️ This comment has been updated with latest results.

github-actions · 2025-10-14T18:07:34Z

Test Results (amd64) - Integration, Bootstrap

5 files 5 suites 1h 24m 14s ⏱️
2 704 tests 2 599 ✅ 105 💤 0 ❌
2 710 runs 2 599 ✅ 111 💤 0 ❌

Results for commit d7e2d4b.

♻️ This comment has been updated with latest results.

maxhoheiser

Greate changes, I noticed a few small gaps and nits, but after these are addressed good to merge.
Good catch that we need the null checks in the _evaluate... methods.

Quite a lot of tests to cover this 👍

Nit:
if (suffix_equal_ignore_case := suffix.get("equals-ignore-case")) is not None: should we use the walrus operator more frequently?

localstack-core/localstack/services/events/event_rule_engine.py

maxhoheiser · 2025-10-15T08:48:35Z

localstack-core/localstack/services/events/event_rule_engine.py

+                    # anything-but can actually contain any kind of simple rule (str, number, and list) except Null
+                    if value is None:
+                        raise InvalidEventPatternException(
+                            f"{self.error_prefix}Value of anything-but must be an array or single string/number value."


Suggested change

f"{self.error_prefix}Value of anything-but must be an array or single string/number value."

f"{self.error_prefix}"Value of anything-but cannot be null. Expected array or string/number value."

nit - this might be clearer that null is absolutely not allowed

This is a parity error returned by AWS, and while I agree with the comment, can't do anything about it 😄

maxhoheiser · 2025-10-15T08:49:11Z

localstack-core/localstack/services/events/event_rule_engine.py

-                            self._validate_rule(v)
+                            if v is None:
+                                raise InvalidEventPatternException(
+                                    f"{self.error_prefix}Inside anything but list, start|null|boolean is not supported."


should this be string? or what is start :)

same comment as above, AWS returns this error, I also don't know what start means 🤷‍♂️

bentsku

Thanks a lot for the review! Also added the missing type hints in the _evaluate_* methods that you spotted, good catch! I've changed them to t.Any to take into the account they could be also something else than None and properly handle those cases to be strictly strings, we're now properly covered I believe.

Edit: regarding the walrus operator, I tend to use it quite frequently, it especially helps here 👍

bentsku · 2025-10-15T13:14:09Z

localstack-core/localstack/services/events/event_rule_engine.py

+                    # anything-but can actually contain any kind of simple rule (str, number, and list) except Null
+                    if value is None:
+                        raise InvalidEventPatternException(
+                            f"{self.error_prefix}Value of anything-but must be an array or single string/number value."


This is a parity error returned by AWS, and while I agree with the comment, can't do anything about it 😄

bentsku · 2025-10-15T13:14:47Z

localstack-core/localstack/services/events/event_rule_engine.py

-                            self._validate_rule(v)
+                            if v is None:
+                                raise InvalidEventPatternException(
+                                    f"{self.error_prefix}Inside anything but list, start|null|boolean is not supported."


same comment as above, AWS returns this error, I also don't know what start means 🤷‍♂️

fix anything-but with null values

d5a9ca3

bentsku added this to the 4.10 milestone Oct 14, 2025

bentsku self-assigned this Oct 14, 2025

bentsku added aws:events Amazon EventBridge semver: patch Non-breaking changes which can be included in patch releases docs: skip Pull request does not require documentation changes notes: skip Pull request does not have to be mentioned in the release notes labels Oct 14, 2025

bentsku marked this pull request as ready for review October 14, 2025 18:08

bentsku requested a review from maxhoheiser as a code owner October 14, 2025 18:08

maxhoheiser approved these changes Oct 15, 2025

View reviewed changes

remove None check and replace with strict string instance check

d7e2d4b

bentsku commented Oct 15, 2025

View reviewed changes

bentsku merged commit 76c6c86 into main Oct 15, 2025
40 checks passed

bentsku deleted the fix-eventbridge-rule branch October 15, 2025 14:08

	f"{self.error_prefix}Value of anything-but must be an array or single string/number value."
	f"{self.error_prefix}"Value of anything-but cannot be null. Expected array or string/number value."

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Events: fix anything-but with null values #13268

Events: fix anything-but with null values #13268

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