feat: optimize Dockerfile (#47)

* define base image arg

* create base stage with common content

* chmod executable entrypoint file

this avoids re-copying the same file as is being modified in the docker
layer

* cache npm downloaded packages

avoids re-downloading deps if cache content is available

docker/Dockerfile

@@ -1,21 +1,29 @@
 # Dockerfile for Open Archiver
 
-# 1. Build Stage: Install all dependencies and build the project
-FROM node:22-alpine AS build
+ARG BASE_IMAGE=node:22-alpine
+
+# 0. Base Stage: Define all common dependencies and setup
+FROM ${BASE_IMAGE} AS base
 WORKDIR /app
 
 # Install pnpm
-RUN npm install -g pnpm
+RUN --mount=type=cache,target=/root/.npm \
+    npm install -g pnpm
 
 # Copy manifests and lockfile
 COPY package.json pnpm-workspace.yaml pnpm-lock.yaml* ./
 COPY packages/backend/package.json ./packages/backend/
 COPY packages/frontend/package.json ./packages/frontend/
 COPY packages/types/package.json ./packages/types/
+
+# 1. Build Stage: Install all dependencies and build the project
+FROM base AS build
 COPY packages/frontend/svelte.config.js ./packages/frontend/
 
 # Install all dependencies. Use --shamefully-hoist to create a flat node_modules structure
-RUN pnpm install --shamefully-hoist --frozen-lockfile --prod=false
+ENV PNPM_HOME="/pnpm"
+RUN --mount=type=cache,id=pnpm,target=/pnpm/store \
+    pnpm install --shamefully-hoist --frozen-lockfile --prod=false
 
 # Copy the rest of the source code
 COPY . .
@@ -24,17 +32,7 @@ COPY . .
 RUN pnpm build
 
 # 2. Production Stage: Install only production dependencies and copy built artifacts
-FROM node:22-alpine AS production
-WORKDIR /app
-
-# Install pnpm
-RUN npm install -g pnpm
-
-# Copy manifests and lockfile
-COPY package.json pnpm-workspace.yaml pnpm-lock.yaml* ./
-COPY packages/backend/package.json ./packages/backend/
-COPY packages/frontend/package.json ./packages/frontend/
-COPY packages/types/package.json ./packages/types/
+FROM base AS production
 
 # Install production dependencies
 # RUN pnpm install --shamefully-hoist --frozen-lockfile --prod=true
@@ -48,7 +46,6 @@ COPY --from=build /app/packages/backend/src/database/migrations ./packages/backe
 
 # Copy the entrypoint script and make it executable
 COPY docker/docker-entrypoint.sh /usr/local/bin/
-RUN chmod +x /usr/local/bin/docker-entrypoint.sh
 
 # Expose the port the app runs on
 EXPOSE 4000