# Pattern: Tenant Isolation

Status: draft
Readiness target: RL3 production
Primary owners: NetKingdom, Railiance platform, product repos

## Problem

Multi-tenant systems fail dangerously when tenant identity, runtime,
data, control-plane authority, or background jobs can cross boundaries
implicitly.

## Context

Use this pattern for SaaS products, shared clusters, shared databases,
object storage, platform services, admin tools, and asynchronous jobs.

## Forces

- Shared infrastructure improves efficiency.
- Tenants need strong data and authorization boundaries.
- Isolation may be implemented at namespace, cluster, cell, database,
  key, policy, or API layers.
- Product teams need a clear contract for carrying tenant context.

## Solution

Make tenant context an explicit security boundary across identity,
authorization, runtime, data, audit, and operations. Choose isolation
strength per risk: namespace, cluster, cell, data partition, or isolated
data plane.

## Implementation Sketch

1. Define tenant id format and trust source.
2. Require tenant context in request and job envelopes.
3. Enforce tenant scope in flex-auth decisions.
4. Partition data and object storage by tenant.
5. Apply runtime and network boundaries for tenant workloads.
6. Record tenant id in audit and detection events.

## Failure Modes

| Failure | Mitigation |
| --- | --- |
| Tenant id accepted from untrusted input | derive from trusted identity/session claims |
| Background jobs lose tenant context | require job envelope tenant binding |
| Shared database queries miss tenant filter | add query guards and tests |
| Control plane can mutate tenant resources globally | add guardrails and review flows |

## Related Capabilities

- Tenant isolation.
- Authorization and access control.
- Data protection and privacy.
- Observability, detection, and audit.

## Maturity

Draft. The capability is central and well described; individual products
need concrete verification patterns.

## Verification

- Cross-tenant access tests fail for APIs, jobs, storage, and admin
  paths.
- Tenant id is present in identity, authorization, and audit records.
- Data access includes tenant partition enforcement.
- Control-plane operations are tenant scoped unless explicitly platform
  scoped.

## Research Basis

Seeded by tenant identity boundary, namespace-per-tenant,
cluster-per-tenant, cell-based architecture, isolated data plane,
tenant context propagation, and tenant data partitioning.

## References

- Initial exploration: Tenant isolation capability group.
- Initial exploration: Tenant isolation patterns.