Fetch headless Chromium at container startup instead of build time

build-and-push failed on the last deploy: chromium-headless-shell's
single ~181MB binary can't be split across Docker layers the way this
project's pip/npm installs were (those are many independently-
installable smaller packages; this is one file), and confirmed-failed
to push past the registry's per-layer size limit.

Moves the `playwright install chromium-headless-shell` step from the
Dockerfile to start.sh, caching into PLAYWRIGHT_BROWSERS_PATH on the
/data volume -- only the very first boot on a fresh volume downloads
it, every boot after that is a no-op check. The image itself no longer
grows by ~262MB, so nothing new gets pushed to the registry at all.

docs/widgets.md

@@ -283,10 +283,16 @@ widgets on the same frame without a Floyd-Steinberg seam at the boundary
 (see that module's docstring for why ordered dithering doesn't have this
 problem and Floyd-Steinberg does) -- no `Frame`-level dithering setting
 was needed. Playwright/Chromium is a real, heavyweight runtime dependency
-imported lazily only when a weather widget actually uses this style, and
+imported lazily only when a weather widget actually uses this style.
-its Docker packaging has a known likely-blocking image-size problem not
+Its browser binary is fetched by `start.sh` at container startup rather
-yet resolved (see `server/Dockerfile`'s own comment) -- treat this style
+than baked into the image (see `server/Dockerfile`'s own comment) --
-as unshipped/local-only until that's sorted out.
+a single ~181MB `chrome-headless-shell` binary can't be split across
+Docker layers the way this project's pip/npm installs were, and
+confirmed-failed to push to the registry as a build-time layer; cached
+on the `/data` volume (`PLAYWRIGHT_BROWSERS_PATH`) so only the very
+first boot on a fresh volume actually downloads it. Still real-panel-
+unverified (see this widget's own render_style rollout notes/PR) --
+treat "modern" style as experimental regardless of deploy status.
 
 `current`/`hourly`/`daily` share one configured location
 (`city_label`/`city_latitude`/`city_longitude`, set via `POST .../

server/Dockerfile

@@ -36,8 +36,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     tzdata fontconfig fonts-dejavu-core nodejs npm \
     && rm -rf /var/lib/apt/lists/*
 
-# EXPERIMENTAL, likely unmergeable as-is -- see below. System libs a
+# EXPERIMENTAL. System libs a headless Chromium needs (app/html_render.py, the weather widget's
-# headless Chromium needs (app/html_render.py, the weather widget's
 # opt-in "modern" render style), trimmed from Playwright's own full
 # `install-deps chromium` list to just what a headless (no Xvfb),
 # Latin-text-plus-emoji use case needs: dropped xvfb (only needed for a
@@ -74,23 +73,23 @@ RUN pip install --no-cache-dir pypdfium2==5.12.1
 RUN pip install --no-cache-dir playwright==1.61.0
 RUN pip install --no-cache-dir -r requirements.txt
 
-# KNOWN LIKELY BLOCKER, not resolved by pulling this into its own layer:
+# The headless Chromium binary itself is deliberately NOT installed
-# `playwright install chromium-headless-shell` unpacks to ~262MB, and its
+# here at build time. `playwright install chromium-headless-shell`
-# single `chrome-headless-shell` binary alone (measured: 181MB) is one
+# unpacks to ~262MB, and its single `chrome-headless-shell` binary alone
-# file -- unlike the pip/npm splits above (independently-installable
+# (measured: 181MB) is one file -- unlike the pip/npm splits above
-# smaller packages moved into their own layers), a single 181MB file
+# (independently-installable smaller packages moved into their own
-# can't be divided across multiple <100MB Docker layers by any ordinary
+# layers), a single 181MB file can't be divided across multiple <100MB
-# COPY/RUN restructuring; the whole file lands in whichever layer's diff
+# Docker layers by any ordinary COPY/RUN restructuring; the whole file
-# contains it. This almost certainly exceeds the same Cloudflare single-
+# lands in whichever layer's diff contains it, which confirmed-failed
-# blob/layer limit that forced the pip/npm splits elsewhere in this file
+# to push to this project's registry (the same Cloudflare single-blob/
-# (see their comments) -- an actual push to this project's registry
+# layer limit that forced the pip/npm splits elsewhere in this file --
-# hasn't been attempted (would require pushing to `main`, which triggers
+# see their comments). Fix: start.sh downloads it at container startup
-# deploy) to confirm, but there is no reason to expect a single 181MB
+# instead, cached on the /data volume (PLAYWRIGHT_BROWSERS_PATH below)
-# blob to fit where combined ~113MB of many small wheels didn't. Needs a
+# so it survives restarts/redeploys and only ever downloads once per
-# real resolution (a registry without this limit, hosting the browser
+# volume, not once per image layer. Trade-off: first boot on a fresh
-# binary outside the image, etc.) before this branch can actually ship --
+# volume needs network access to Playwright's CDN -- true of Immich/
-# tracked as open, not silently assumed away.
+# weather API access too, so not a new requirement for this server.
-RUN playwright install chromium-headless-shell
+ENV PLAYWRIGHT_BROWSERS_PATH=/data/.playwright-browsers
 
 # render-service/'s dependencies installed as several separate layers
 # rather than one `npm install` covering all of them -- a from-scratch

server/start.sh

@@ -5,6 +5,18 @@
 # Then execs uvicorn as the foreground/PID 1 process so it receives
 # Docker's stop signal directly.
 #
+# Before either: fetch headless Chromium (app/html_render.py, the
+# weather widget's opt-in "modern" render style) into
+# PLAYWRIGHT_BROWSERS_PATH (set in the Dockerfile to a path on the /data
+# volume) if it isn't already cached there -- see the Dockerfile's own
+# comment for why this happens at startup instead of build time. Only
+# the very first boot on a fresh volume actually downloads anything;
+# every boot after that is a no-op ls check.
+if [ -z "$(ls -A "$PLAYWRIGHT_BROWSERS_PATH" 2>/dev/null)" ]; then
+  echo "Fetching headless Chromium into $PLAYWRIGHT_BROWSERS_PATH (first boot on this volume)..." >&2
+  playwright install chromium-headless-shell
+fi
+#
 # Wrapped in a restart loop, not a bare `node ... &`: a bare background
 # process that crashes stays dead for good, with nothing to bring it
 # back -- turning any single render crash (a not-yet-found jsdom/