Comparison
Build vs buy: RAG authorization
Many engineering teams start with a custom authorization layer for their RAG pipeline. Most discover three months in that the scope is larger than it appeared. This page maps what building it actually entails and where teams typically run out of runway.
Bottom line
A prototype is quick: a metadata filter, a principal lookup, a role check. Production is the part teams underestimate, covering fail-closed handling on every evaluation error path, an audit trail that answers who accessed what and when, IDP sync that keeps up with group changes, credential encryption, policy versioning and regression tests, with each additional vector database multiplying the connector work. Gateco ships those as a permission-aware retrieval layer; building is still the right call when your policy model cannot be expressed in RBAC, ABAC or ReBAC conditions, or when vendor dependency is a hard constraint.
| Capability | Gateco | Build yourself |
|---|---|---|
| First working prototype | ~10 minutes (connect a DB) | 1–2 weeks |
| Production-ready with fail-closed default Fail-closed requires explicitly handling every evaluation error path | Yes | No |
| Audit trail (principal, resource, policy, decision) Audit trail typically deferred until a compliance requirement forces it | Yes | No |
| IDP sync (auto-updates on group changes) IDP sync is usually the longest-tail item; effort varies per provider | Yes | No |
| 12 vector DB connectors Most builds cover 1–2 connectors; additional connectors multiply effort | Yes | On roadmap |
| Policy versioning | Yes | No |
| Retroactive resource registration | Yes | No |
| Credential encryption at rest (KMS envelope) | Yes | No |
| Rate limiting on retrieval endpoints | Yes | No |
| SCIM v2 provisioning | Yes | No |
| MCP server for LLM tool use | Yes | No |
| CI test coverage for auth regressions Authorization regression tests are almost always absent from DIY builds | Yes | No |
| Full ownership / no vendor dependency | No | Yes |
| Custom policy language | No | Yes |
What teams underestimate when building
The initial proof-of-concept is fast. A metadata filter on your vector DB results, a principal lookup from your user table, a simple role check. This takes a day or two. The hidden surface area emerges when you move toward production: you need to handle the case where the IDP is temporarily unreachable (fail-closed or fail-open?), you need an audit trail that can answer “who accessed this document on which date,” you need policies that update automatically when a user changes departments, and you need all of this to add only a measured 21ms p95 of policy-layer overhead to your retrieval latency (end-to-end latency varies by connector and search mode).
The common failure mode is not that the DIY approach is wrong in principle. It is that authorization is treated as a project rather than a product. It launches with the minimum viable implementation, grows a backlog of deferred items (IDP sync, policy versioning, credential rotation), and becomes a maintenance burden that competes with product work.
When building is the right choice
Building your own authorization layer is the right choice when your policy model is genuinely unique and cannot be expressed in RBAC/ABAC/ReBAC conditions, when you need a policy language your security team already owns (Rego, Cedar), when you have deep infrastructure engineering capacity and a long time horizon, or when vendor dependency is a hard constraint. Gateco is not the right choice for all of these situations.
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