# Service Mesh Interface (SMI)

**Canonical:** https://apis.io/providers/service-mesh-interface/  
**Website:** https://smi-spec.io  
**APIs profiled:** 4

Service Mesh Interface (SMI) was a CNCF Sandbox specification that defined a standard, vendor-neutral set of Kubernetes Custom Resource Definitions (CRDs) for the most common service mesh capabilities: traffic policy, traffic telemetry, and traffic management. SMI's stated mission was "a standard interface for service meshes on Kubernetes," letting operators write portable traffic policy that worked across Linkerd, Open Service Mesh, Consul Connect, Istio (via adapter), Traefik Mesh, Gloo Mesh, and others without lock-in. The specification reached v0.6.0 (January 2021 / republished January 2024) and defined four resource groups across distinct API versions: Traffic Access Control (v1alpha3), Traffic Specs (v1alpha4), Traffic Split (v1alpha4), and Traffic Metrics (v1alpha1). Active development ceased in July 2022 when the maintainers shifted focus to the Kubernetes SIG-Network GAMMA initiative inside the Gateway API project. CNCF formally archived SMI on October 3, 2023, with the GitHub org and all repositories marked read-only on October 20, 2023. The CNCF announcement stated: "the maintainers have decided to consolidate efforts on a service mesh under the auspices of GAMMA under the Kubernetes SIG Network initiative." Gateway API GAMMA reached GA in the Standard Channel with Gateway API v1.1.0 and is now the de facto Kubernetes standard for service mesh configuration, superseding SMI. This profile documents SMI as a historical/archived standard. It is preserved so consumers of the API Evangelist network can (a) recognize legacy SMI manifests still deployed in the wild, (b) understand the conceptual lineage that fed into Gateway API GAMMA, and (c) migrate off SMI to Gateway API.

## Kin Score — 17.7 / 100 (emerging)

Scored 2026-08-25 under rubric 0.14.0. Trend: flat (+0.0 from 17.7).

| Facet | Score |
|---|---|
| Discoverability | 64.8 |
| Contract Quality | 30.7 |
| Governance | 25.0 |
| Contract Governance | 25.0 |
| Operational Transparency | 5.3 |
| Developer Ergonomics | 7.1 |
| Commercial Clarity | 0.0 |
| Access Clarity | 0.0 |

Regulatory layer — **Insurance**: 16.7 (matched via tags).

## Agent readiness — 1.3 (human-only)

| Dimension | Value |
|---|---|
| Spec Presence | no |
| Agentic Access | no |
| Reversibility Documented | no |
| MCP Server | no |
| Auth Clarity | no |
| Idempotency | no |
| Error Semantics | no |
| OpenAPI Examples | documented |
| Rate Limit Signal | no |
| Event Surface Described | no |
| Agent Skills | no |
| Well Known Catalog | no |
| Consent Identity | no |
| Agent Card | no |
| Dry Run Mode | no |
| Delegated Identity | no |
| Protected Resource Metadata | no |
| Dynamic Client Registration | no |
| Agentic Commerce | no |

## Access

Unknown — onboarding: unknown, pricing: unknown, trial: no (confidence: low).

## APIs (4)

- **SMI Traffic Access Control** — Traffic Access Control defines the `TrafficTarget` resource, which associates a set of traffic rules with a service identity allocated to a group of pods. It is the authorizatio...
- **SMI Traffic Specs** — Traffic Specs describes a set of resources that allow users to specify how their traffic looks. It is used in concert with access control and other policies to concretely define...
- **SMI Traffic Split** — Traffic Split defines the `TrafficSplit` resource, which allows users to incrementally direct percentages of traffic between various services. It is the canonical SMI primitive ...
- **SMI Traffic Metrics** — Traffic Metrics is "a resource that provides a common integration point for tools that can benefit by consuming metrics related to HTTP traffic." It is exposed as a Kubernetes A...

## Security (1)

- **Service Mesh Interface Domain Security** — TLSv1.3 · HSTS

## Tags

Service Mesh, Kubernetes, Traffic Policy, Traffic Management, Traffic Metrics, Standards, CNCF, Archived, Specification, Custom Resource Definitions

---

Profiled by [API Evangelist](https://apievangelist.com) and published on [APIs.io](https://apis.io/providers/service-mesh-interface/). Scores are computed from the provider's own public artifacts under a published rubric.