fix slow serving of static files by precompressing them

Dockerfile

@@ -1,6 +1,6 @@
 # Build stage:
-FROM node:14-alpine as builder
-
+FROM node:16-alpine as builder
+RUN apk add --no-cache brotli
 # Build-time env variables
 ARG SENTRY_DSN
 ARG PATH_PREFIX
@@ -26,6 +26,10 @@ ENV NODE_ENV=production
 # Build all packages
 RUN npm run build
 
+# precompress static files for frontend
+RUN find packages/ilmomasiina-frontend/build -type f\
+  -regex ".*\.\(js\|json\|html\|map\|css\|svg\|ico\|txt\)" -exec gzip -k "{}" \; -exec brotli "{}" \;
+
 # Main stage:
 FROM node:16-alpine
 

packages/ilmomasiina-backend/src/app.ts

@@ -80,17 +80,10 @@ export default async function initApp(): Promise<FastifyInstance> {
     }
   }
 
-  // Add on-the-fly compression
-  server.register(fastifyCompress, { inflateIfDeflated: true });
-
-  server.register(setupRoutes, {
-    prefix: '/api',
-    adminSession: new AdminAuthSession(config.feathersAuthSecret),
-  });
-
   // Serving frontend files if frontendFilesPath is not null.
   // Ideally these files should be served by a web server and not the app server,
   // but this helps run a low-effort server.
+  // frontend files should not be gzipped on the fly, rather done on the build step.
   if (config.frontendFilesPath) {
     console.info(`Serving frontend files from '${config.frontendFilesPath}'`);
     server.register(fastifyStatic, {
@@ -102,6 +95,13 @@ export default async function initApp(): Promise<FastifyInstance> {
       reply.sendFile('index.html');
     });
   }
+  // Add on-the-fly compression
+  server.register(fastifyCompress, { inflateIfDeflated: true });
+
+  server.register(setupRoutes, {
+    prefix: '/api',
+    adminSession: new AdminAuthSession(config.feathersAuthSecret),
+  });
 
   // Every minute, remove signups that haven't been confirmed fast enough
   cron.schedule('* * * * *', deleteUnconfirmedSignups);