Deploy: production Docker stack for a single host (Synology/QNAP NAS)

Everything needed to run the app on an Intel NAS that is also doing other
jobs: one published port, no host networking, memory/CPU caps and log
rotation on every container, and all state in bind mounts under DATA_ROOT
so mail survives image updates, project deletion in the NAS UI, and full
reinstalls — and so Hyper Backup/HBS3 can actually see it.

- docker/Dockerfile.backend: multi-stage, non-root (uid 10001), tini for
  the <10s graceful lease release. Installs the four plugins as entry-point
  distributions. One image, several roles via docker/entrypoint.sh
  (api | worker-sync | worker-jobs | migrate | reindex | plugins).
- docker/Dockerfile.frontend + nginx.conf: SPA + /api reverse proxy with
  the WebSocket upgrade for /api/ws, and X-Forwarded-Proto preserved so
  the API still emits __Host-/Secure cookies when TLS is terminated by
  the NAS reverse proxy (identity/cookies.py keys off request scheme).
- docker/docker-compose.prod.yml: project name webmail-prod, NOT webmail —
  docker-compose.yml (dev services) owns that name, and two compose files
  sharing one project name fight over each other's containers.
  Meilisearch is an opt-in profile; SEARCH_BACKEND=pg is the default so a
  small NAS pays nothing for search.
- migrate runs as a one-shot (core Alembic head + every plugin branch)
  that everything else waits on, so a bad migration can never leave new
  code running against an old schema.
- docker/backup.sh: nightly pg_dump verified with `pg_restore --list`
  before it counts as a backup, with retention and a baseline on first
  start.
- deploy/webmail.sh: init/doctor/up/down/status/logs/update/rollback/
  backup/restore/reindex/psql/shell. `update` is backup -> images ->
  migrate -> roll workers, api, web -> health-gate, with automatic
  rollback to the previous version if the gate fails. `doctor` refuses to
  be quiet when DATA_ROOT is on NFS/SMB (silent Postgres corruption).
- deploy/build-push.sh: build images off-NAS (the frontend build wants
  ~2GB RAM) and push to Gitea, or --save a tar to carry over.
- scripts/reindex_search.py: rebuild the search index from Postgres alone.
  Every SearchDoc field is already stored, so the index is derived data
  that never needs backing up — this closes the only real objection to
  running Meilisearch on a box whose volumes may be wiped.
- pyproject: package-data for accounts/presets.yaml and the shared plugin
  Alembic env. Without it a non-editable install (i.e. any image) silently
  ships a package that fails at runtime.
- GET /api/version, used by the deploy health gate.

Verified end to end on a real stack: fresh install, all services healthy,
core + 4 plugin migration branches applied, login/SPA/plugin bundles
through nginx, WS upgrade returning 101, __Host- cookies under a
simulated TLS proxy, backup -> restore round-trip preserving user and
plugin schema, failed-update auto-rollback (both a bad migration and a
boot-crashing API), and Meilisearch profile serving a live query.
ruff + mypy --strict clean, 363/363 backend tests pass.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Nux3LCu4zP9nih4BRhPyHw

docker/Dockerfile.backend

@@ -0,0 +1,79 @@
+# Production backend image: API, both worker roles, and the migration/admin CLI.
+#
+# One image, several commands (see docker/entrypoint.sh) — matches SPEC §6.3's
+# WORKER_ROLE split. Build context is the REPO ROOT, because the image needs
+# backend/ *and* plugins/ (the five plugins are separate distributions that the
+# loader discovers through the `webmail.plugins` entry-point group, SPEC §11).
+#
+#   docker build -f docker/Dockerfile.backend -t webmail/backend .
+
+# ---------- builder: resolve wheels into a self-contained venv ----------------
+FROM python:3.11-slim AS builder
+
+ENV PIP_DISABLE_PIP_VERSION_CHECK=1 \
+    PIP_NO_CACHE_DIR=1 \
+    PYTHONDONTWRITEBYTECODE=1
+
+# Only needed if a pinned dep has no manylinux wheel for this platform; the
+# whole stage is discarded, so it costs nothing in the runtime image.
+RUN apt-get update \
+ && apt-get install -y --no-install-recommends build-essential \
+ && rm -rf /var/lib/apt/lists/*
+
+RUN python -m venv /opt/venv
+ENV PATH="/opt/venv/bin:$PATH"
+
+# Backend first: its dependency set is the slowest layer and changes least often.
+COPY backend/pyproject.toml /src/backend/pyproject.toml
+COPY backend/app /src/backend/app
+COPY backend/workers /src/backend/workers
+RUN pip install /src/backend
+
+# Plugins are ordinary distributions installed on top (each owns its own deps).
+COPY plugins /src/plugins
+RUN pip install \
+      /src/plugins/webmail_plugin_calendar \
+      /src/plugins/webmail_plugin_contacts \
+      /src/plugins/webmail_plugin_labels \
+      /src/plugins/webmail_plugin_filters
+
+# ---------- runtime -----------------------------------------------------------
+FROM python:3.11-slim
+
+ARG APP_VERSION=dev
+ARG GIT_SHA=unknown
+LABEL org.opencontainers.image.title="webmail-backend" \
+      org.opencontainers.image.version="${APP_VERSION}" \
+      org.opencontainers.image.revision="${GIT_SHA}"
+
+ENV PYTHONUNBUFFERED=1 \
+    PYTHONDONTWRITEBYTECODE=1 \
+    PATH="/opt/venv/bin:$PATH" \
+    APP_VERSION="${APP_VERSION}" \
+    GIT_SHA="${GIT_SHA}"
+
+# tini reaps zombies and forwards SIGTERM, which the workers need for the <10 s
+# graceful lease release in workers/run.py.
+RUN apt-get update \
+ && apt-get install -y --no-install-recommends tini \
+ && rm -rf /var/lib/apt/lists/* \
+ && useradd --system --uid 10001 --create-home --home-dir /home/webmail webmail
+
+COPY --from=builder /opt/venv /opt/venv
+
+WORKDIR /app
+# Alembic's core tree lives outside the installed package, so it is copied in.
+COPY backend/alembic.ini ./alembic.ini
+COPY backend/migrations ./migrations
+COPY backend/scripts ./scripts
+COPY docker/entrypoint.sh /usr/local/bin/entrypoint
+RUN chmod +x /usr/local/bin/entrypoint
+
+# Blob store mount point (BLOB_ROOT). Ownership is set by the compose `init`
+# service, which runs before anything else touches the bind mount.
+RUN mkdir -p /data/blobs && chown webmail:webmail /data/blobs
+VOLUME ["/data/blobs"]
+
+USER webmail
+ENTRYPOINT ["/usr/bin/tini", "--", "/usr/local/bin/entrypoint"]
+CMD ["api"]