Cairn

Durable, resolvable hosting for preservation standards. Powers standards.openpreservation.org.

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Why this exists

The Open Preservation Foundation (OPF) has agreed to host the TS-EAS Encoded Archival Standards: EAF, EAD, & EAC-CPF, under a stable domain it controls, with more standards (E-ARK, for instance) to follow. The schemas' source of truth stays upstream (GitHub); Cairn pulls each release into a locally-controlled, integrity-checked, write-once replica and serves it under a permanent URL scheme.

Design principles:

• Preserve, don't redirect. We serve our own verified copies so URLs keep resolving even if upstream disappears. Every artifact carries a SHA-256 and provenance record.
• Static-first, dumb serving layer. All the logic is in an offline build step; nginx just serves files. Schema URLs resolve forever even when the tooling is idle.
• Manifest-driven. Adding or updating a standard is a small YAML edit reviewed as a pull request - not bespoke engineering. This is how the platform scales without scaling OPF's effort.

The URL contract

For a standard eaf, major line v1, latest release v1.0.0:

URL	Serves
/	Registry index of all hosted standards
/eaf	Human landing page for the standard (all versions, stewards, links, downloads)
/eaf/v1	Namespace document - readable XHTML that is also a machine-readable RDDL directory pointing at the current v1 schema files. XML clients that ask for application/xml are content-negotiated to the schema.
/eaf/v1/eaf.xsd	303 → the latest concrete v1.x.y file (pin-to-latest-minor)
/eaf/v1.0.0	Landing page for that exact release (downloads + checksums + provenance)
/eaf/v1.0.0/eaf.xsd	The actual schema file - application/xml, immutable cache, CORS *

Namespace = major version only (/eaf/v1). Minor/patch numbers never appear in a namespace, so a minor release never forces a namespace change. The exact version lives in the schema's schema-version attribute and in the concrete /vX.Y.Z/ release folders.

How it works

The registry is a set of YAML manifests. Three commands turn them into a served site:

  standards/<id>/standard.yaml    the registry: identity, upstream source, releases, artifacts

  1. cairn validate      check every manifest against schemas/standard.schema.json
  2. cairn sync          fetch artifacts, verify SHA-256, record provenance, freeze
                         (writes the write-once replica to site/<id>/vX.Y.Z/)
  3. cairn build         render landing pages, RDDL, catalog.json, sitemap, nginx routes
                         (writes site/ and build/nginx/cairn-routes.conf)

  nginx (:8080, plain HTTP)       serves site/ behind the ingress layer

Quick start

python -m venv .venv && . .venv/bin/activate
pip install -e .

cairn validate            # lint every manifest
cairn sync                # replicate + checksum upstream artifacts into site/
cairn build               # render pages + routing into site/ and build/nginx/

# serve it locally (publishes 127.0.0.1:8080)
docker compose -f deploy/docker-compose.yml -f deploy/docker-compose.local.yml up --build
curl -i http://localhost:8080/eaf/v1.0.0/eaf.xsd

See CONTRIBUTING.md to add or update a standard.

Deployment

The stack is three small services around two shared volumes:

• syncer replicates + renders into the volumes on a loop (every 6h by default), so a newly merged standard appears without a manual rebuild. It reads manifests from the image-baked copy, a bind-mounted checkout, or a git clone (REPO_URL) - see deploy/docker-compose.yml.
• web (nginx) serves the volumes on :8080 (plain HTTP), seeds them on first boot from a baked snapshot, and reloads periodically to pick up new routes.
• cloudflared (opt-in) provides ingress via a Cloudflare Tunnel: no inbound ports, TLS at the edge.

Ingress modes:

# Local testing (publishes 127.0.0.1:8080):
docker compose -f deploy/docker-compose.yml -f deploy/docker-compose.local.yml up -d --build

# Cloudflare Tunnel (no host ports; set CLOUDFLARE_TUNNEL_TOKEN in deploy/.env first):
docker compose --profile tunnel up -d --build

If you would rather sit behind OPF's own TLS-terminating reverse proxy, point it at the internal web:8080 (see deploy/reverse-proxy.example.conf) and skip the tunnel profile. See deploy/ for all of the above plus .env.example.

Licence

Tooling: Apache-2.0 (see LICENSE). Hosted standards remain under their upstream licences; each release records its provenance.