add updated dockerfile for dokku

Dockerfile

@@ -1,19 +1,69 @@
-# Production Environment Dockerfile
+FROM node:20-alpine AS base
 
-# base image
-FROM node:alpine
-
-# create & set working directory
-RUN mkdir -p /app
+# Install dependencies only when needed
+FROM base AS deps
+# Check https://github.com/nodejs/docker-node/tree/b4117f9333da4138b03a546ec926ef50a31506c3#nodealpine to understand why libc6-compat might be needed.
+RUN apk add --no-cache libc6-compat
 WORKDIR /app
 
-# copy source files
-COPY . /app
+# Install dependencies based on the preferred package manager
+COPY package.json yarn.lock* package-lock.json* pnpm-lock.yaml* ./
+RUN \
+  if [ -f yarn.lock ]; then yarn --frozen-lockfile; \
+  elif [ -f package-lock.json ]; then npm ci; \
+  elif [ -f pnpm-lock.yaml ]; then corepack enable pnpm && pnpm i --frozen-lockfile; \
+  else echo "Lockfile not found." && exit 1; \
+  fi
 
-# install dependencies
-RUN npm install
 
-# start app
-RUN npm run build
+# Rebuild the source code only when needed
+FROM base AS builder
+WORKDIR /app
+COPY --from=deps /app/node_modules ./node_modules
+COPY . .
+
+# Next.js collects completely anonymous telemetry data about general usage.
+# Learn more here: https://nextjs.org/telemetry
+# Uncomment the following line in case you want to disable telemetry during the build.
+# ENV NEXT_TELEMETRY_DISABLED 1
+
+RUN \
+  if [ -f yarn.lock ]; then yarn run build; \
+  elif [ -f package-lock.json ]; then npm run build; \
+  elif [ -f pnpm-lock.yaml ]; then corepack enable pnpm && pnpm run build; \
+  else echo "Lockfile not found." && exit 1; \
+  fi
+
+# Production image, copy all the files and run next
+FROM base AS runner
+WORKDIR /app
+
+ENV NODE_ENV production
+# Uncomment the following line in case you want to disable telemetry during runtime.
+# ENV NEXT_TELEMETRY_DISABLED 1
+
+RUN addgroup --system --gid 1001 nodejs
+RUN adduser --system --uid 1001 nextjs
+
+COPY --from=builder /app/public ./public
+
+# Set the correct permission for prerender cache
+RUN mkdir .next
+RUN chown nextjs:nodejs .next
+
+# Automatically leverage output traces to reduce image size
+# https://nextjs.org/docs/advanced-features/output-file-tracing
+COPY --from=builder --chown=nextjs:nodejs /app/.next/standalone ./
+COPY --from=builder --chown=nextjs:nodejs /app/.next/static ./.next/static
+
+USER nextjs
+
 EXPOSE 3000
-CMD npm run start
+
+ENV PORT 3000
+# set hostname to localhost
+ENV HOSTNAME "0.0.0.0"
+
+# server.js is created by next build from the standalone output
+# https://nextjs.org/docs/pages/api-reference/next-config-js/output
+CMD ["node", "server.js"]

next.config.mjs

@@ -9,6 +9,7 @@
 /** @type {import("next").NextConfig} */
 const config = {
   reactStrictMode: true,
+  output: "standalone",
 
   /**
    * If you have the "experimental: { appDir: true }" setting enabled, then you