Do not include dev npm packages in final image

futurehome/Dockerfile

@@ -4,12 +4,20 @@ FROM ${BUILD_FROM}
 # ---------- install NodeJS ----------
 RUN apk add --no-cache nodejs npm python3 make g++
 
-# ---------- copy source -------------
+# ---------- copy source & build -----
 WORKDIR /usr/src/app
-COPY package.json tsconfig.json ./
-RUN npm install
+COPY package.json package-lock.json tsconfig.json ./
+
+# ① install EVERYTHING (prod + dev)
+RUN npm ci
+
 COPY src ./src
+
+# ② compile TypeScript
 RUN npm run build
 
+# ③ throw dev stuff away so the final image stays small
+RUN npm prune --omit=dev
+
 # ---------- copy s6 service files ---
 COPY rootfs /