tegwick
6b0ededee2
Decides long-lived runner Deployment with DinD sidecar; updates RAIL-HO-WP-0005 runner model decision.
104 lines
4.1 KiB
Markdown
104 lines
4.1 KiB
Markdown
# ADR-004 — Forgejo In-Cluster Actions Runner on railiance01
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**Status:** Accepted
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**Date:** 2026-07-03
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**Deciders:** Bernd Worsch (operator), custodian agents
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**Workplans:** `RAIL-HO-WP-0005-T02`, `CUST-WP-0054-T04`
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---
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## Context
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Forgejo production runs on **railiance01 k3s** (`railiance-apps`, S5). An interim
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**host runner** on coulombcore proved Actions scheduling (`coulomb/forgejo-actions-probe`)
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but:
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- coulombcore is a legacy machine slated for drain (CUST-WP-0054-T03).
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- Host runners require Docker or Podman on the OS — not installed, not desired on
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coulombcore long term.
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- Forgejo upstream recommends **not** co-locating runners on the same machine as the
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forge instance; in-cluster **separate pods** satisfy isolation while staying on the
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production fleet node.
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- `RAIL-HO-WP-0005-T02` left the runner model undecided among host, in-cluster, and
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ephemeral options.
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Goal: a **coherent Kubernetes-from-the-start** CI substrate — Forgejo app, database,
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ingress, and Actions runner all lifecycle-managed on railiance01.
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## Decision
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### Runner placement
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Deploy **one long-lived Forgejo Actions runner Deployment** in the `forgejo` namespace
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on railiance01:
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| Component | Implementation |
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| --- | --- |
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| Runner | `data.forgejo.org/forgejo/runner:6.3.1` |
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| Container runtime for jobs | `docker:dind` sidecar (privileged) |
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| State | PVC `forgejo-runner-data` (`.runner`, `config.yaml`, action cache) |
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| Registration scope | `coulomb` organization |
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| Runner name | `railiance01-build-01` |
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| Deploy surface | `railiance-apps/manifests/forgejo-runner.yaml` |
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| Operator targets | `make forgejo-runner-deploy`, `forgejo-runner-status` |
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### Label contract
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Preserve Gitea migration compatibility and semantic capability labels:
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```text
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self-hosted:host,linux:host,linux_amd64:host,container-build:host,registry-publish:host,railiance01:host,ubuntu-latest:docker://node:20-bookworm,docker:docker://node:20-bookworm
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```
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### Security boundaries
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- Runner pod receives **no** cluster-admin kubeconfig and **no** OpenBao tokens by default.
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- `registry-publish` jobs use **repo/org-scoped Forgejo secrets** only.
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- DinD sidecar runs **privileged** — accepted for single-node railiance01 with
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dedicated `forgejo` namespace; revisit when a third node or multi-tenant runners appear.
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- Registration tokens live in Kubernetes Secret `forgejo-runner-registration` (SOPS
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template committed; live value never in Git).
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### Retire interim host runner
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Stop and disable `forgejo-runner.service` on coulombcore after in-cluster runner is
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healthy. Do not register new host runners without an explicit ADR amendment.
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## Alternatives considered
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| Option | Outcome |
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| --- | --- |
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| Host runner + Docker on coulombcore | Rejected — legacy host, contradicts drain plan |
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| Host runner + Podman on haskelseed | Viable fallback; not chosen as primary |
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| Kaniko/Buildah without DinD | Deferred — higher workflow churn during Gitea migration |
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| Multiple ephemeral runner Jobs | Deferred — start with capacity=1 long-lived pod |
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## Consequences
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**Positive**
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- Single-machine production loop: forge + runner on railiance01, workstation not required.
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- Container image CI (`docker build` / `docker push`) works without OS-level Docker.
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- Runner upgrades roll with Git-managed manifests and `kubectl`/Makefile.
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**Negative / follow-on**
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- Privileged DinD increases blast radius within the node — monitor and restrict namespace RBAC.
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- SOPS-encrypted registration secret still requires operator age key.
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- `cluster-deploy` / `s5-release-check` labels remain **out of scope** until credential paths reviewed.
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## Ownership (OAS)
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| Concern | Repo | Layer |
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| --- | --- | --- |
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| ADR + umbrella sequencing | `railiance-infra` | S1 |
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| Runner manifests + Makefile | `railiance-apps` | S5 |
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| Label contract + runner evidence docs | `railiance-forge` | S5 forge substrate |
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| Reusable workflow templates | `railiance-enablement` | S4 |
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## References
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- `railiance-apps/docs/forgejo-on-railiance01.md`
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- `railiance-forge/docs/forgejo-actions-runner-substrate.md`
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- `the-custodian/docs/forgejo-production-decisions.md`
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- [Forgejo runner installation](https://forgejo.org/docs/v11.0/admin/actions/runner-installation/) |