Add KafkaErrorDetector for producer/consumer error detection

[sandeshgorde]

Closes #1

Added KafkaErrorDetector to detect common Kafka producer/consumer failures in Spring Boot logs.

Changes

• KafkaErrorDetector.java — detects ProducerFencedException, CommitFailedException, WakeupException, org.apache.kafka.common.errors at ERROR severity
• IssueClassifier.java — registered new detector
• AllDetectorsTest.java — 5 tests covering all patterns + negative case.

Summary by CodeRabbit

• New Features

  • Added Kafka error detection that identifies and reports Kafka-related runtime errors with actionable remediation guidance.
  • Detects specific Kafka exceptions including producer, consumer group, and broker-related issues.

• Tests

  • Added comprehensive test coverage for Kafka error detection scenarios.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 11e23c8f-e55b-4a29-8b81-2d1af498c6b7

📥 Commits

Reviewing files that changed from the base of the PR and between 4db9d9c and f87eb98.

📒 Files selected for processing (1)

• src/main/java/com/stacklens/detector/KafkaErrorDetector.java

📝 Walkthrough

Walkthrough

A new KafkaErrorDetector is implemented to identify Kafka runtime errors matching ProducerFencedException, CommitFailedException, WakeupException, and org.apache.kafka.common.errors patterns. The detector is registered in IssueClassifier and covered by comprehensive test cases.

Changes

Kafka Error Detection

Layer / File(s)	Summary
Detector Implementation src/main/java/com/stacklens/detector/KafkaErrorDetector.java	New detector class implements IssueDetector, scans log lines for Kafka error signatures (ProducerFencedException, CommitFailedException, WakeupException, org.apache.kafka.common.errors), and returns an Issue with type "KafkaError", severity ERROR, descriptive message, and remediation hints.
Classifier Registration src/main/java/com/stacklens/classifier/IssueClassifier.java	KafkaErrorDetector is registered in the ERROR-severity detector list immediately after TransactionErrorDetector.
Tests src/test/java/com/stacklens/detector/AllDetectorsTest.java	Five new test methods verify detection of ProducerFencedException, CommitFailedException, WakeupException, common Kafka errors, and confirm non-detection of clean lines.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• AbaSheger/stacklens#7: Both PRs add a new IssueDetector implementation and register it in IssueClassifier's constructor
• AbaSheger/stacklens#8: Both PRs add ERROR-severity detectors and register them in IssueClassifier

Poem

🐰 Kafka errors hop no more,
A new detector at the door,
Fenced and wakeful, caught with care,
Stacklens debugs with rabbit flair! 🥕

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely summarizes the main change: adding KafkaErrorDetector for Kafka error detection.
Description check	✅ Passed	The PR description covers the primary objective and lists all changed files with clear explanations of modifications.
Linked Issues check	✅ Passed	All requirements from issue #1 are met: all four patterns detected, ERROR severity applied, KafkaErrorDetector implemented and registered.
Out of Scope Changes check	✅ Passed	All code changes are directly related to Kafka error detection implementation and testing; no out-of-scope modifications detected.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

🧹 Nitpick comments (1)

src/test/java/com/stacklens/detector/AllDetectorsTest.java (1)

263-290: ⚡ Quick win

Strengthen Kafka positive tests with type/severity assertions.

These tests currently only check isPresent(). Please also assert getType() (and ideally getSeverity()) so regressions in emitted metadata are caught, not just matching behavior.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@src/test/java/com/stacklens/detector/AllDetectorsTest.java` around lines 263
- 290, Update the three Kafka tests
(kafkaErrorDetector_detectsCommitFailedException,
kafkaErrorDetector_detectsWakeupException,
kafkaErrorDetector_detectsKafkaCommonErrors) to not only assert
result.isPresent() but also validate the emitted Issue metadata: call
result.get() and assert its getType() equals the expected Kafka type emitted by
KafkaErrorDetector (use the detector's declared type constant or literal used by
KafkaErrorDetector) and assert getSeverity() equals the expected severity value
(use the severity constant from KafkaErrorDetector or the Severity enum value
the detector is intended to produce). This ensures the tests verify
Issue.getType() and Issue.getSeverity() in addition to presence.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@src/test/java/com/stacklens/detector/AllDetectorsTest.java`:
- Around line 263-290: Update the three Kafka tests
(kafkaErrorDetector_detectsCommitFailedException,
kafkaErrorDetector_detectsWakeupException,
kafkaErrorDetector_detectsKafkaCommonErrors) to not only assert
result.isPresent() but also validate the emitted Issue metadata: call
result.get() and assert its getType() equals the expected Kafka type emitted by
KafkaErrorDetector (use the detector's declared type constant or literal used by
KafkaErrorDetector) and assert getSeverity() equals the expected severity value
(use the severity constant from KafkaErrorDetector or the Severity enum value
the detector is intended to produce). This ensures the tests verify
Issue.getType() and Issue.getSeverity() in addition to presence.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 14ebf4f5-e2c6-4859-9be6-0ed67e8ed4e8

📥 Commits

Reviewing files that changed from the base of the PR and between f374a42 and 4db9d9c.

📒 Files selected for processing (3)

• src/main/java/com/stacklens/classifier/IssueClassifier.java
• src/main/java/com/stacklens/detector/KafkaErrorDetector.java
• src/test/java/com/stacklens/detector/AllDetectorsTest.java

[AbaSheger]

Reviewed the Kafka detector changes. The implementation is scoped to Kafka producer/consumer error patterns, the detector is registered in the classifier, and CI is passing on the latest commit. There is one minor follow-up suggestion to strengthen a few positive tests with type/severity assertions, but it is not blocking this merge. Thanks for the contribution.

[AbaSheger]

Thanks again for adding the Kafka error detector. I verified the merged project locally with mvn clean verify; all 88 tests passed and the build completed successfully.