[matthewberry]

Problem

nginx/default.conf sets no Cache-Control on the app's own files, so browsers fall back to heuristic freshness based on Last-Modified. Every file in the image carries the build time as its mtime, so on a deployment that has been running for a while a browser can treat index.html as fresh for a day or more without revalidating. After a new image rolls out, that stale index.html requests hashed bundles that no longer exist, and try_files $uri /index.html answers with index.html and a 200, producing module MIME-type / "failed to fetch dynamically imported module" errors until a hard refresh. The nginx:1.23.3 base image also ships with gzip commented out, so the main bundle goes over the wire uncompressed.

This is the fleet rollout of moleculemaker/CLEANDB-frontend#60 (reviewed there). The generator source for new projects is fixed in moleculemaker/frontend-dev-tools#11 and moleculemaker/frontend-template#7.

Change

One file, nginx/default.conf.

Path class	Cache-Control	Notes
Hashed build output: root-level [name].<16+ lowercase hex>.<ext>, which is how the legacy webpack browser builder names every hashed file: bundles, lazy chunks, and the fonts and images referenced from CSS all land at the root	public, max-age=31536000, immutable	A missing hashed file is a real 404 instead of falling through to index.html
/assets/config/envvars.json	no-store	Written by entrypoint.sh at container start
Everything else (index.html, SPA routes, favicon.ico, everything under assets/)	no-cache	ETag/Last-Modified still sent; revalidated on every use

Plus gzip on with gzip_vary, gzip_min_length 1024, and types for CSS, JS, JSON, SVG and EOT (HTML is always included; woff/woff2 and images are already compressed).

Immutable rule: ^/[^/]+\.[0-9a-f]{16,}\.[A-Za-z0-9]+$. It is case-sensitive and anchored to the root so that files copied verbatim from src/assets (never hashed) are excluded; none of this repo's assets match it. The regex is quoted because nginx otherwise reads the {n} brace as a block opener.

The hash is 16 hex characters, not the 20 the [contenthash:20] template suggests, because build-angular sets webpack's hashFunction to xxhash64 (a 64-bit digest). Verified against a real Angular 15 build (main.9637a10c19cda006.js); the rule accepts 16 or more so a longer digest in a later version still matches. This is a different rule from the one in CLEANDB-frontend#60, which uses the application builder's -XXXXXXXX format; that rule would match nothing here.

This repo has no proxy location, so none is carried over.

• try_files $uri /index.html; becomes try_files $uri /index.html =404; to match the other frontends. No behavior change: /index.html always exists so the =404 arm is never reached.

Verification

The new file was built into a FROM nginx:1.23.3 image with this repo's Dockerfile COPY lines and entrypoint.sh, started with the env vars from envvars.tpl.json, and probed with curl against a production ng build of clean-frontend (Angular 15, webpack browser builder, outputHashing: all). nginx -t passed. Fake files were added for the edge probes (ketcher… at the root to prove the immutable rule wins over any proxy rule; a hashed file with an unlisted extension).

Path	Status	Cache-Control
/	200	no-cache	OK
/index.html	200	no-cache	OK
/some/spa/route	200	no-cache	OK
/main.9637a10c19cda006.js	200	public, max-age=31536000, immutable	OK
/styles.8f037a6bbdf88809.css	200	public, max-age=31536000, immutable	OK
/color.dae87a04d07ca92b.png	200	public, max-age=31536000, immutable	OK
/ketcher.0123456789abcdef0123.js	200	public, max-age=31536000, immutable	OK
/main.deadbeefdeadbeefdead.js	404	(none)	OK
/nope.0123456789abcdef0123.png	404	(none)	OK
/assets/config/envvars.json	200	no-store	OK
/assets/price_maxsep.csv	200	no-cache	OK
/favicon.ico	200	no-cache	OK

SPA route body is index.html: yes
gzip main: 781829 -> 249467 bytes (1 Content-Encoding header)
envvars.json substituted by entrypoint: yes

Not verified: requests to the proxy upstream (the block is unchanged), and behavior behind the ingress. Also not closed: the rolling-update window where a new index.html is served by a new pod and a chunk is requested from an old one; that is now a hard 404 (recoverable with a reload) rather than a heuristically cacheable 200 with HTML, and the fix belongs in the chart.

[matthewberry]

Added one more commit: exec nginx in entrypoint.sh. bash as PID 1 never forwarded SIGTERM to nginx, so a stopping container ran out its full termination grace period. Measured on the runtime image: docker stop -t 30 took 30 s before, 0 s after. In Kubernetes the old pod was therefore still serving for the whole grace period after the new pod became Ready, which is the rolling-update window the "not closed" note above describes. With exec it shrinks to endpoint propagation, and each rollout finishes about 30 s sooner. The probe harness still passes with the new entrypoint (config substitution, all headers, gzip).

[matthewberry]

Checked (independently of the PR body): the head nginx/default.conf was run in nginx:1.23.3 with a synthetic file tree and probed with curl. nginx -t passes. Headers land in the intended classes: /, /index.html and an SPA route are no-cache; hashed files are public, max-age=31536000, immutable and a missing hashed name is a hard 404; /assets/config/envvars.json is no-store; assets/* is no-cache; JS and CSS over 1 KiB come back Content-Encoding: gzip. The hash regex is the webpack form (.[0-9a-f]{16,}), which is what this repo's browser builder emits; probed with both 16- and 20-hex names. angular.json (@angular-devkit/build-angular:browser, outputHashing: all) and the Dockerfile COPY path (dist/clean) match the layout the rules assume. The base image's STOPSIGNAL is SIGQUIT, so with exec nginx the container now gets nginx's graceful shutdown rather than sitting out the grace period.

Findings: none.