Design an LLM gateway layer that centralizes model access, controls, and observability for an organization.
Organization: {{org_size}} engineers using LLMs
Providers in use: {{providers}}
Compliance requirements: {{compliance}}
Goals: {{goals}} (cost control, observability, safety, multi-model routing)
1. What an LLM gateway provides:
- Single access point: all LLM calls from all teams go through the gateway
- Authentication and authorization: teams have API keys; keys map to budgets and allowed models
- Rate limiting: per-team, per-user, and per-model limits
- Logging: centralized log of all requests and responses
- Routing: send requests to the cheapest capable model; fall back on provider outage
- Cost allocation: track spend by team, project, and use case
2. Gateway architecture:
Reverse proxy layer:
- Accepts LLM API requests (OpenAI-compatible interface)
- Injects authentication headers to the upstream provider
- Returns the provider response, adding gateway metadata headers
Policy engine:
- Per-request policy: allowed models, max tokens, required safety filters
- Per-tenant policy: monthly budget cap, rate limit, allowed providers
- Dynamic routing rules: route based on latency, cost, or model capability
Logging and analytics:
- Log: timestamp, tenant ID, user ID, model, input token count, output token count, latency, cost
- Do NOT log: raw prompt or response if they may contain PII (log hashes only in sensitive contexts)
- Analytics: daily cost dashboard per team, latency trends, error rates
3. Open-source and commercial options:
- LiteLLM Proxy: open-source, OpenAI-compatible, supports 100+ providers, includes rate limiting and logging
- PortKey: commercial gateway with advanced analytics
- Kong AI Gateway: enterprise-grade API gateway with LLM plugins
- Azure API Management: enterprise gateway if already on Azure
- AWS Bedrock API Gateway: for AWS-native deployments
4. PII and compliance:
- Data residency: route requests to providers in the correct geographic region
- PII scrubbing: scan and redact PII before logging (not before sending to the model unless required)
- GDPR / HIPAA: document which providers are used, their DPA status, and data retention policies
5. Reliability:
- Provider health checks: detect provider outages before they affect users
- Automatic failover: route to secondary provider if primary is unavailable
- SLA: gateway adds < 5ms overhead to every request
Return: gateway architecture, policy engine design, logging specification, open-source vs commercial recommendation, and compliance controls.