How do I keep partner APIs isolated from internal services?

A good way to keep partner APIs isolated from internal services is to treat them as separate trust zones and connect them only through controlled boundaries.

Core approach

1. Put partner APIs in a DMZ / edge zone

   • Expose them only through an API gateway or reverse proxy.
   • Do not allow direct access to internal service networks.

2. Use network segmentation

   • Separate partner-facing services from internal services with VPCs, subnets, firewall rules, or Kubernetes namespaces/network policies.
   • Allow only specific, explicit traffic paths between zones.

3. Apply a gateway or BFF layer

   • Partner APIs should talk to a dedicated integration layer, not directly to core services.
   • That layer can validate requests, transform payloads, and enforce policy.

4. Use service-to-service authentication

   • Require mTLS, short-lived tokens, or signed requests between all components.
   • Never rely on network location alone.

5. Minimize data exposure

   • Create partner-specific DTOs/views.
   • Avoid sharing internal models or internal endpoints.
   • Return only the fields and operations the partner needs.

6. Separate credentials and secrets

   • Use distinct IAM roles, secrets, and key sets for partner-facing components.
   • Rotate credentials independently.

7. Enforce authorization at the boundary

   • Each partner gets scoped access.
   • Use allowlists for routes, methods, tenants, and data domains.

8. Add monitoring and rate limits

   • Log partner traffic separately.
   • Rate limit, quota-limit, and anomaly-detect partner requests to protect internal systems.

Common patterns

• API Gateway + internal microservices
• Partner adapter service
• Anti-corruption layer
• B2B integration hub
• Event-driven integration where partners interact with a narrow event/API surface instead of core services

Rule of thumb

If a partner API needs something from an internal service, prefer:

• a dedicated adapter/API facade
• a specific internal service endpoint
• and strict policy enforcement rather than exposing the internal service directly.

If you want, I can sketch a reference architecture for AWS, Kubernetes, or on-prem.