dorfteich/docs/architecture/adr/0024-reproducible-offline-deployment.md

ADR 0024: Reproducible offline deployment

• Status: proposed
• Date: 2026-07-29

Context

A VS zone has no internet egress. "Should work offline" is the answer that loses a first meeting; "tested, here is the procedure" is the one that wins it — which is why the plan pulled this out of the roadmap into Phase 1.

The current state is favourable but unverified. There is no telemetry, no update check, no CDN; fonts are self-hosted (ADR 0016); CSP is default-src 'self'; search is Postgres rather than an external engine; the drawio plugin is vendored rather than loaded from a remote editor. What is missing is evidence, plus two real gaps: images are referenced by tag (including the floating gotenberg/gotenberg:8), and there is no documented mirror or update path.

Decision

1. All third-party images are pinned by digest (name:tag@sha256:…). The tag stays for human readability; the digest decides what runs. A CI check rejects any un-digested third-party reference.
2. The image list is generated, not hand-maintained, so a mirror procedure cannot silently miss a service.
3. An internal registry is the supported source. Compose takes the registry prefix from configuration; no site edits image references.
4. Reproducibility without network is a stated choice between two paths: an offline pnpm store enabling install + build with networking disabled, or prebuilt images only with no customer-side build. Either is acceptable; leaving it unstated is not, because it determines whether the customer can patch locally.
5. The airgap claim is proven by a documented run in a network-isolated environment, covering every function including the export sidecars, and listing every outbound connection attempt observed. This run is the artefact, and it also answers the plan's open question about what breaks offline.
6. The offline update path is part of the decision, not an afterthought: bundle, verify by digest, back up, apply, verify, roll back — with the irreversibility of migrations stated explicitly.

Decisions taken in #219

• Both paths, with stated roles: customers OPERATE prebuilt, digest-pinned images (the CI release build; mirrored per #218) — no customer-side build for operation. ADDITIONALLY the workspace build is verified to work with networking disabled, so site-local patching remains possible (open source as an audit advantage) — the "no local patching" consequence therefore does not apply.
• The offline kit is the pnpm store plus the build user's ~/.cache (the prisma postinstall pulls its engines from there instead of the network) — both filled by one online pnpm install --frozen-lockfile.
• Evidence: pnpm install --offline --frozen-lockfile and pnpm build under docker run --network none (node:22.15.1-alpine, pnpm 11.9.0 — the pinned toolchain), reproduced twice from clean checkouts (docs/vs-nfd/96-offline-build-protokoll.md).
• The one network dependency found: the drawio plugin's installable ZIP fetches its pinned vendor tarball on first build. Deploy images contain no plugin ZIPs, so the delivery-relevant build is fully offline (CI=1 skips the fetch, as in CI); for an offline ZIP build the tarball is pre-seeded into packages/plugins/drawio/vendor/.

Consequences

• Digest pinning creates recurring maintenance: security updates now require an explicit, reviewable change. That visibility is the point.
• Digest pinning must precede the mirror and update work, so it sits in the hardening & supply chain milestone rather than this one.
• The isolated test run will surface findings; each becomes its own issue referenced from #220 rather than expanding that issue's scope.
• Outbound SMTP is the one connection an authority may or may not permit; the deployment must be functional without it, and the consequences of disabling it (no notifications, no verification mail — which interacts with auth.local.enabled = false) are documented.
• CD does not sync stage composes, so digest changes need an explicit rollout step on the stage hosts.

Implementing issues

#203 (digest pinning), #218 (registry mirror), #219 (network-free build), #220 (isolated test run), #221 (offline update path), #236 (pinned Node version — added from the Ist-Aufnahme, I-26).