Replace session key in cache integration with placeholder

[cleptric]

A fix was implemented to prevent session keys from appearing as cache keys in Sentry's session overview.

• Three new private methods were added to src/Sentry/Laravel/Features/CacheIntegration.php:
  • isSessionKey(string $key): bool determines if a given cache key matches the current session ID, handling prefixed keys and ensuring sessions are not prematurely started.
  • replaceSessionKey(string $key): string replaces a detected session key with the placeholder {sessionKey}.
  • replaceSessionKeys(array $keys): array applies the replacement logic to arrays of keys.
• Existing event handlers in src/Sentry/Laravel/Features/CacheIntegration.php were updated to utilize these new methods:
  • handleCacheEventsForBreadcrumbs now replaces session keys in breadcrumb messages.
  • handleCacheEventsForTracing replaces session keys in span descriptions and cache.key data for cache.get, cache.put, and cache.remove operations.
  • handleRedisCommands also applies the replacement to Redis command descriptions and parameters.
• Comprehensive tests were added to test/Sentry/Features/CacheIntegrationTest.php to verify session key replacement in breadcrumbs and spans, and to confirm that the integration does not prematurely start sessions.

This ensures session IDs are consistently anonymized as {sessionKey} in Sentry data, improving readability and privacy.

[cleptric]

@sentry review

[seer-by-sentry]

On it! We are reviewing the PR and will provide feedback shortly.

[seer-by-sentry]

PR Description

This pull request enhances the privacy of cache telemetry data collected by the Sentry Laravel integration. Its primary goal is to prevent sensitive session identifiers from being inadvertently included in breadcrumbs and spans, which could expose user data.

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Key Technical Changes

The key technical change is the introduction of session key masking. This is achieved by:

1. Adding a getSessionKey() method to retrieve the current session ID.
2. Implementing replaceSessionKey() and replaceSessionKeys() methods to replace session keys with the placeholder {sessionKey} in cache keys before they are added to breadcrumbs and span data.

These changes affect how cache keys are displayed in Sentry's UI, replacing sensitive information with a generic placeholder.

Architecture Decisions

The architectural decision is to perform session key replacement within the CacheIntegration class, specifically when handling cache events for breadcrumbs and tracing. This approach centralizes the privacy logic and ensures consistent masking across different telemetry data types. The session key is retrieved from the Laravel session store using the session.store binding.

Dependencies and Interactions

This change depends on the Laravel session component. It interacts with the cache event system to intercept cache operations and modify the associated data. It also interacts with the Sentry SDK to add breadcrumbs and create spans. The changes are isolated to the CacheIntegration class and should not directly affect other parts of the system, except for the data displayed in Sentry's UI.

Risk Considerations

The primary risk is that the session key replacement logic might not be comprehensive enough to cover all possible scenarios where session keys could appear in cache keys. For example, if session keys are used as prefixes or embedded within larger strings, the replacement logic might fail. Additionally, there's a performance overhead associated with retrieving the session key and performing the string replacement, although this is expected to be minimal. Error handling in getSessionKey() is also a point to consider, as exceptions during session retrieval could lead to unexpected behavior.

Notable Implementation Details

A notable implementation detail is the use of a static closure in replaceSessionKeys(). While functional, it captures the $sessionKey from the outer scope, creating an implicit dependency. Also, the getSessionKey() method retrieves the session store from the container on every call. Caching the session key within the request lifecycle could improve performance. The tests include checks for correct session key replacement and ensure that sessions are not started prematurely.

[Copilot]

Pull Request Overview

This PR ensures that session IDs are anonymized as {sessionKey} in Sentry breadcrumbs, spans, and Redis command data by replacing any detected session key in cache and Redis integrations.

• Introduces methods to retrieve the current session ID and replace it (and arrays of keys) with a placeholder.
• Updates cache and Redis event handlers to apply the replacement logic to breadcrumb messages, span descriptions, and parameters.
• Adds comprehensive tests to verify placeholder substitution and prevent premature session starts.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
test/Sentry/Features/CacheIntegrationTest.php	Added tests for replacing session keys with {sessionKey} in breadcrumbs and spans, and verifying no premature session start.
src/Sentry/Laravel/Features/CacheIntegration.php	Added getSessionKey, replaceSessionKey, replaceSessionKeys methods and updated event handlers to use them.

Comments suppressed due to low confidence (1)

test/Sentry/Features/CacheIntegrationTest.php:196

• There’s no test for session keys stored with a cache prefix. Adding a test case that uses a prefixed session ID (e.g., prefix_{$sessionId}) would ensure the replacement logic covers those scenarios.

    public function testCacheSpanReplacesMultipleSessionKeysWithPlaceholder(): void

[cleptric]

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