301f88575d
Assistant: codex Assistant-Model: gpt-5.6-sol Assistant-Session: 01a02994-7685-7940-bf34-3555b8256018
69 lines
2.3 KiB
Markdown
69 lines
2.3 KiB
Markdown
---
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id: RINFRA-ADR-0005
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type: adr
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title: "k3s API is tunnel-only"
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status: accepted
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owner: railiance-infra
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revision: "accepted-1"
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last_reviewed: "2026-08-22"
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review_interval: 6m
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---
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# ADR-005 — k3s API is tunnel-only
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**Status:** Accepted
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**Date:** 2026-08-15
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**Deciders:** implementation of RAIL-HO-WP-0009-T04
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**Workplans:** `RAIL-HO-WP-0009`
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---
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## Context
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Operator addresses on this network rotate with the ISP lease. A public UFW
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allowlist for `6443/tcp` is therefore a treadmill:
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- miss a rotation and `kubectl` breaks mid-session
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- leave the old grant standing and it becomes a grant to a stranger
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- hand-add the new address and the declaration drifts again
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That cycle produced this workplan. The live allowlist drifted by hand *during
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the session that was fixing allowlist drift*, and again before the next
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session (`89.244.90.248` appeared undeclared). On 2026-08-15 the workstation
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egress address was `85.132.220.102` — already on the revoked list as a
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"historic" operator address.
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`docs/deploy-stack.md` already documents API access over the ops-bridge SSH
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tunnel for CoulombCore (`k3s-api-coulombcore`, local port 16443). The same
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tunnel already exists for Railiance01 (`k3s-api-railiance01`, local port
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16444). SSH itself stays public, so the host remains recoverable.
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## Decision
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The public k3s API allowlist is **empty**. Operator and agent `kubectl` access
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uses the ops-bridge tunnels:
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| Cluster | Tunnel | Local port | Remote |
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|-------------|-------------------------|------------|--------|
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| CoulombCore | `k3s-api-coulombcore` | 16443 | 6443 |
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| Railiance01 | `k3s-api-railiance01` | 16444 | 6443 |
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```bash
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bridge up k3s-api-railiance01
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# kubeconfig server: https://127.0.0.1:16444
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```
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Trade: every operator `kubectl` action depends on ops-bridge. That is accepted.
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A rotating public allowlist is the worse dependency.
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Emergency break-glass remains SSH: `ssh railiance01 -- sudo k3s kubectl …`.
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Do not re-open `6443/tcp` to Anywhere.
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## Consequences
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- `k3s_api_allowed_sources` stays `[]`.
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- Former public grants live in `k3s_api_revoked_sources` so a firewall-tagged
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converge deletes them.
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- Goss asserts the 6443 allowlist size is exactly the declared length (zero)
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and that no revoked address remains.
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- Amending this ADR is required before adding any new public 6443 source.
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