---
id: RMASTER-ADR-0008
title: "Private-by-default Exposure"
status: accepted
revision: "accepted-1"
owner: railiance-master
last_reviewed: "2026-08-15"
review_interval: 6m
---

# ADR-0008: Private-by-default Exposure

Date: 2026-08-15
Status: Accepted

## Context

ADR-0006 says a topology binding is not permission to run a workload in
production. It does not say who may reach a listener. A working deploy,
a `hosts_rail` / `binds_rapp` line, or an Ingress object has been enough
to put something on the public internet.

Family readiness vocabularies are deliberately not unified
(`schemas/README.md`). Reef `lifecycle_state` has no
`production-approved`. Rapp `readiness_state` has no
`production-approved` either. Exposure cannot be derived from those
enums.

Live public surfaces already exist on `reef-railiance`. They must be
named as grants, not silently grandfathered and not taken down by this
decision.

Ratified 2026-08-15 under `RMASTER-WP-0023-T01`.

## Decision

New reefs, rails, and rapps are unreachable from the public internet
until they are production-safe **and** explicitly granted. The field
name is `exposure`. Missing field means `private`.

| Posture | Meaning | Who may reach it |
| --- | --- | --- |
| `private` | No extra listener we control | in-cluster DNS, same-reef services |
| `operator` | Same listener as `private`, plus a named ops-bridge / SSH tunnel | operator and approved agents |
| `public` | Internet listener we publish | anyone the Ingress / DNS / UFW surface allows |

`operator` is an access annotation, not a different packet posture. It
does not open a host port or a public Ingress.

Default for a new reef, rail, or rapp is `private`. Use `operator` only
for a named admin or API surface that must be reachable before admission
(k3s API, OpenBao UI). Do not prefer `operator` as the debug default.

`public` requires both an ADR-0006 binding of `production-approved` and
an explicit grant. A deploy, a binding line, or an Ingress object is not
a grant. Do not key `public` off rapp `readiness_state` and do not add
`production-approved` to the rapp enum for this purpose.

A reef public surface (host port or public DNS we publish) is a
**substrate grant**, not reef `lifecycle_state`. A rapp cannot be
`public` on a reef that has not granted a public surface. Conflicting
declarations fail closed.

The shared vocabulary is one enum. It is not one schema shape and not
one admission check:

| Family | What the field means | What makes `public` legal |
| --- | --- | --- |
| `rapp-*` | intended consumer-facing listener | binding `production-approved` + grant |
| `rail-*` | which listener classes the rail may emit | rail may emit public Ingress only when a bound grant exists |
| `reef-*` | host ports and public DNS we publish | substrate grant |

A grant is accepted residual risk, not a self-serve wish. Required
fields: hostname or port, reason, `approved_on`, residual-risk owner.

`6443` / the k3s API is not a grantable public surface.

This contract covers listeners we control: host ports, Ingress, Service
types, and public DNS we publish. Provider-native internet APIs
(Scaleway S3 and other provider-delegated endpoints) are outside this
enum.

Ops-bridge is the normal path to a shielded thing.

The detailed per-family reading lives in
[`docs/exposure-posture-contract.md`](../exposure-posture-contract.md).

## Consequences

- ADR-0006 still answers "may this binding run in production?" This ADR
  answers "who may reach the listener?" Do not merge the axes.
- The three readiness enums stay distinct on purpose.
- Family schemas grow an additive `exposure` field. Rapp
  `data_classification: public` is a different field and must not be
  reused as the posture name.
- Implementation stays in the owning repos. This ADR does not install
  NetworkPolicy, UFW, Ingress, or tunnels.
- Existing public surfaces on `reef-railiance` remain up until named as
  grants. This ADR is not a shutdown plan.
- CoulombCore host inventory and Q7 / Goss reaction stay outside this
  decision.