Add Pillar Security guardrail integration

Relevant issues

Pre-Submission checklist

Please complete all items before asking a LiteLLM maintainer to review your PR

• I have Added testing in the tests/litellm/ directory, Adding at least 1 test is a hard requirement - see details
• I have added a screenshot of my new test passing locally

Type

🆕 New Feature

Changes

Overview

This PR implements a comprehensive Pillar Security guardrail integration for LiteLLM, providing advanced security features including prompt injection protection, PII detection, secret detection, and content moderation.

Core Features Implemented

⚙️ Technical Features:

• Multi-mode Execution: Support for pre_call, during_call, and post_call modes
• Configurable Actions: block (raise exception) or monitor (log only) on flagged content
• Session Tracking: Comprehensive conversation context analysis via metadata
• Async Implementation: Full async/await support for optimal performance
• Error Handling: Robust error handling with custom exception types

Files Added

Core Implementation:

• litellm/proxy/guardrails/guardrail_hooks/pillar/pillar.py - Main PillarGuardrail class with async hooks
• litellm/proxy/guardrails/guardrail_hooks/pillar/__init__.py - Module initialization and registry
• litellm/types/proxy/guardrails/guardrail_hooks/pillar.py - Pydantic configuration model

Testing:

• tests/guardrails_tests/test_pillar_guardrails.py - Comprehensive test suite (623 lines) with:
  • Configuration validation tests
  • Pre/during/post-call hook tests
  • Clean and flagged content scenarios
  • Error handling and edge cases
  • Payload and session tracking tests
  • Mocked API responses for reliable testing

Documentation:

• docs/my-website/docs/proxy/guardrails/pillar_security.md - Complete user guide (408 lines) with:
  • Quick start guide and setup instructions
  • Multiple configuration examples (security vs. performance trade-offs)
  • API reference and usage examples
  • Troubleshooting and support information

Files Modified

Configuration Integration:

• litellm/types/guardrails.py - Added PILLAR enum value and PillarGuardrailConfigModel
• docs/my-website/sidebars.js - Added Pillar documentation to sidebar navigation

Configuration Examples

Recommended Dual-Mode Configuration:

guardrails:
  - guardrail_name: "pillar-dual-protection"
    litellm_params:
      guardrail: pillar
      mode: [pre_call, post_call]            # Monitor both input and output
      api_key: os.environ/PILLAR_API_KEY
      api_base: os.environ/PILLAR_API_BASE
      on_flagged_action: "monitor"           # Log threats but allow requests
      default_on: true

Alternative Configurations:

• Input-only blocking for maximum security
• Low-latency monitoring for performance-critical applications
• Full monitoring for analytics and compliance

Integration Approach

• Follows LiteLLM Patterns: Uses established guardrail patterns and base classes
• Environment Variable Support: Supports PILLAR_API_KEY, PILLAR_API_BASE, PILLAR_ON_FLAGGED_ACTION
• Metadata Integration: Uses LiteLLM's metadata system for session tracking
• Async-First: Built with async/await for optimal performance
• Error Resilience: Graceful degradation on API failures with detailed error reporting

Testing Coverage

• Configuration Tests: Validates setup with/without API keys
• Hook Integration Tests: Tests pre_call, moderation, and post_call hooks
• Content Scenarios: Safe content, prompt injection, secrets detection
• Error Handling: API failures, malformed responses, network issues
• Edge Cases: Empty messages, missing fields, malformed data
• Session Management: User ID and session ID extraction and tracking