Add incremental build + multi layer docker for size reduction (#259)

* Add incremental build + multi layer docker for size reduction

* Update .dockerignore

* fix cache miss

* pr comment .gitignore

---------

Co-authored-by: Eliott C <coyotte508@gmail.com>

.dockerignore

@@ -0,0 +1,8 @@
+Dockerfile
+.vscode/
+.idea
+.gitignore
+LICENSE
+README.md
+node_modules/
+.svelte-kit/

Dockerfile

@@ -1,18 +1,31 @@
 # read the doc: https://huggingface.co/docs/hub/spaces-sdks-docker
 # you will also find guides on how best to write your Dockerfile
-
-FROM node:19
-
-RUN npm install -g pm2
+FROM node:19 as builder-production
 
 WORKDIR /app
 
-COPY --link --chown=1000 package.json package-lock.json ./
+COPY --link --chown=1000 package-lock.json package.json ./
+RUN --mount=type=cache,target=/app/.npm \
+        npm set cache /app/.npm && \
+        npm ci --omit=dev
+
+FROM builder-production as builder
 
-RUN npm i
+RUN --mount=type=cache,target=/app/.npm \
+        npm set cache /app/.npm && \
+        npm ci
 
 COPY --link --chown=1000 . .
 
-RUN --mount=type=secret,id=DOTENV_LOCAL,dst=.env.local npm run build
+RUN --mount=type=secret,id=DOTENV_LOCAL,dst=.env.local \
+    npm run build
+
+FROM node:19-slim
+
+RUN npm install -g pm2
+
+COPY --from=builder-production /app/node_modules /app/node_modules
+COPY --link --chown=1000 package.json /app/package.json
+COPY --from=builder /app/build /app/build
 
-CMD pm2 start build/index.js -i $CPU_CORES --no-daemon
+CMD pm2 start /app/build/index.js -i $CPU_CORES --no-daemon