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Add dated Status sections and (where missing) Consequences sections assembled from each ADR's already-stated implications. No decision substance changed. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
139 lines
6.6 KiB
Markdown
139 lines
6.6 KiB
Markdown
# ADR-015 — Control / development / AI-worker host (`ubongo`)
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## Status
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Accepted (2026-06-05)
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## Context
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Earlier ADRs framed the control node — the host that runs Terraform and Ansible —
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as a **single Debian 13 VM on the Proxmox cluster**, manually provisioned as the one
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documented exception to "Terraform owns VM existence" (ADR-009). That framing treats
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the control node purely as a control-plane runner.
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It fails four needs, all confirmed as drivers:
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1. **Cold-start bootstrap** — the VM that runs Terraform/Ansible cannot exist until
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something else creates it; the bootstrap is circular and awkward.
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2. **Always-on availability** — the operator wants to SSH in from a work PC or
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anywhere to drive Claude Code. A cluster VM is gone whenever the cluster is down
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or being rebuilt.
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3. **Recovery / disaster** — the tool used to rebuild the cluster must not live
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inside the thing it rebuilds.
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4. **Dev ergonomics** — a persistent home for Claude Code + the repo, not entangled
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with production VM lifecycle.
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A laptop-only answer fails always-on and recovery. A VM-only answer fails cold-start
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and recovery. A small dedicated always-on physical machine outside the cluster
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satisfies all four.
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## Decision
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Introduce **`ubongo`** (Swahili: *brain*, consistent with the fleet's theme): a
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single dedicated x86-64 mini-PC, always-on, living **outside** the Proxmox cluster.
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It becomes *the* control node and collapses four roles into one box:
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- Terraform + Ansible runner (control plane)
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- Claude Code / AI-worker host the operator SSHes into
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- Local test runner (Molecule/Docker, lint, and later a browser stack)
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- Persistent dev home for the repo
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There is **no longer a control VM on the cluster.** The `control` inventory group
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points at this physical box. This *strengthens* the ADR-009 control-node exception:
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it is genuinely outside Terraform's world, not a VM pretending to be the exception.
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Every other host stays a Terraform-managed VM exactly as designed.
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`ubongo` runs **plain Debian 13** (the `base` role applies). It is not a hypervisor
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and runs no `docker_host` services.
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### Hardware target
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| Spec | Target | Why |
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|---|---|---|
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| CPU | 4 cores, x86-64 (Intel N100-class or better) | Molecule containers + Chromium prefer x86 |
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| RAM | 16 GB | Docker + headless Chromium + toolchain headroom |
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| Disk | 250 GB SSD/NVMe | Docker images, molecule layers, repos, browser cache |
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| Network | Wired GbE | Always-on reliability over Wi-Fi |
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| Power | Low draw (≤15 W idle) | Runs 24/7 |
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Indicative: a refurb Dell/Lenovo/HP micro (USFF) or an N100 mini-PC (~€150–250).
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Claude Code itself is light (the model runs in Anthropic's cloud); the sizing driver
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is **all testing being local** — Molecule (Docker), lint, and a future
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headless-Chromium/Playwright stack.
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### Provisioning (bootstrap path)
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Manual, on bare metal:
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1. Install Debian 13 on the box (one-time, by hand).
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2. `git clone` the repo; `make setup`; `make collections`; set up `rbw` + unlock.
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3. Join the mesh VPN — NetBird, self-hosted on `askari` (ADR-016).
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4. From then on `ubongo` manages every other host normally; Ansible manages *it* for
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baseline config via the `control` group (`base` role only).
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### Access & security
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- Remote access is via the **mesh VPN** — NetBird, self-hosted on `askari` (ADR-016).
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SSH to `ubongo` over the mesh; nothing is published to the public internet — this
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stays inside ADR-002.
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- `ubongo` runs the `base` role: SSH hardening, nftables default-deny, fail2ban,
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auditd, unattended-upgrades. Inbound SSH is allowed **only on the mesh interface**,
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denied on the physical NIC.
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### Recovery model
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`ubongo` is the rebuild tool, so three things must survive a full cluster loss:
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1. **`mamba` (laptop) is a break-glass clone** — repo + toolchain + mesh + `rbw`,
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able to drive the fleet if `ubongo` dies.
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2. **Terraform state** lives on `ubongo`, backed up encrypted off-box (synced to
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`mamba`). For a 2–5 VM fleet it is also reconstructable via `terraform import`.
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3. **Vault password** — `ubongo` gets it from Vaultwarden via `rbw`. `rbw` keeps a
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local encrypted copy of the vault and decrypts it offline with the operator's
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Vaultwarden master password, so `ubongo` can decrypt the Ansible vault with the
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whole cluster down — provided `rbw` has synced once and the operator keeps the
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Vaultwarden master password offline (memorised + paper in a safe). Mirror onto
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`mamba`.
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There is always exactly one irreducible offline root secret; here it is the
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Vaultwarden master password. Mirroring Vaultwarden onto `ubongo` is rejected: it
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would make the control node run a service (against its remit) and still need that
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master password.
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> verified: rbw offline-cache decryption · TO VERIFY before relying on the recovery
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> model · rbw docs · (ADR-014, security-relevant — confirm during build)
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## Consequences
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- The control node is physical compute outside the cluster, so it appears in
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`docs/hardware/reference.md` even though it is not a cluster node (ADR-012).
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- All testing (Molecule, lint, staging/external) runs on `ubongo` (ADR-008).
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- A future **service-UI acceptance** testing level (Claude driving a headless browser
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against a deployed service) is anticipated; `ubongo` is sized for it. The harness
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is a separate spec.
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## Deferred (separate specs / discussions)
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1. **Mesh VPN choice — RESOLVED (ADR-016):** NetBird, self-hosted on `askari`
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(off-site, so it survives a homelab outage and stays out of the cluster it
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administers). Replaces ADR-007's OPNsense WireGuard.
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2. **Browser-E2E verification harness — RESOLVED (ADR-017):** Claude-driven
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exploratory service-UI verification (`/verify-service`, ADR-008 Level 4), against
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staging with test users in Authentik. Design + skill + standards complete; running
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deferred on the stack.
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3. **`rbw` offline-cache verification** — still open: confirm offline decryption before
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relying on it (ADR-014).
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## What was ruled out
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| Option | Reason |
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| Keep control node as a cluster VM | Fails cold-start, recovery, always-on. |
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| Laptop-only (`mamba` for everything) | Fails always-on. Retained as break-glass backup. |
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| Split roles (control VM + thin jump box) | Two toolchains, split control plane, heavy testing back on a cluster VM. |
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| Mirror Vaultwarden onto `ubongo` | Control node would run a service; still needs the master password. |
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| Self-hosted mesh coordinator on the cluster | Recreates the chicken-and-egg. |
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| Raspberry Pi | Chokes running Docker + Chromium + toolchain together. |
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See also: ADR-001 (architecture), ADR-005 (bootstrapping), ADR-008 (testing),
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ADR-009 (provisioning handoff), ADR-012 (hardware/capacity), ADR-002 (security).
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