Error: Cannot find module '/app/apps/backend/dist/server.js' inside docker container

I have a pnpm workspace application which I'm trying to Dockerize. I get to build the images and containers, but the apps won't run inside it.

Basic structure is:

omnimart/
├── apps/
│   ├── backend/        → Express.js REST API
        └── Dockerfile  → Backend Dockerfile
│   └── frontend/       → Next.js 15 App Router
        └── Dockerfile  → Frontend Dockerfile
|   └── orders.json     → Orders JSON database           
├── packages/
│   └── shared/         → Shared types, constants, schemas, and utils        
├── package.json        → Workspace root
├── tsconfig.json       → Root TypeScript config
├── tsconfig.build.json → Root TypeScript build config
├── README.md
├── .dockerignore       → Files for Docker ignore
└── docker-compose.yml  → Docker orquestration

The container runs and builds and get online, then I get: Error: Cannot find module '/app/apps/backend/dist/server.js' and also [email protected] start /app/apps/frontend next start next: not found.

I'm not understanding what I'm doing wrong here. Can anyone help me Dockerize this?

Dockerfile frontend:

# ---- Builder ----
FROM node:20-slim AS builder
WORKDIR /app

RUN npm install -g pnpm

# Copy monorepo files
COPY package.json pnpm-lock.yaml pnpm-workspace.yaml ./
COPY apps/frontend/package.json ./apps/frontend/
COPY apps/backend/package.json ./apps/backend/
COPY tsconfig.json tsconfig.build.json ./

# Install dependencies with cache
RUN pnpm install --frozen-lockfile

# Copy source
COPY . .

# Build Next.js app
RUN pnpm --filter omnimart build


# ---- Runner ----
FROM node:20-slim AS runner
WORKDIR /app/apps/frontend

RUN npm install -g pnpm

ENV NODE_ENV=production

# Copy production files
COPY --from=builder /app/apps/frontend/package.json ./
COPY --from=builder /app/node_modules ./node_modules
COPY --from=builder /app/apps/frontend/.next ./.next
COPY --from=builder /app/apps/frontend/next.config.ts ./next.config.ts

EXPOSE 3000

CMD ["pnpm", "start"]

Dockerfile backend:

# ---- Builder ----
FROM node:20-slim AS builder
WORKDIR /app

RUN npm install -g pnpm

# Copy monorepo files
COPY package.json pnpm-lock.yaml pnpm-workspace.yaml ./
COPY apps/backend/package.json ./apps/backend/
COPY apps/frontend/package.json ./apps/frontend/
COPY tsconfig.json tsconfig.build.json ./

# Install dependencies with cache
RUN pnpm install --frozen-lockfile

# Copy the entire monorepo
COPY . .

# Build backend
RUN pnpm --filter backend run build


# ---- Runner ----
FROM node:20-slim AS runner
WORKDIR /app/apps/backend

RUN npm install -g pnpm

ENV NODE_ENV=production

# Copy production files
COPY --from=builder /app/apps/backend/package.json ./
COPY --from=builder /app/node_modules ./node_modules
COPY --from=builder /app/apps/backend/dist ./dist

EXPOSE 3333

CMD ["node", "dist/server.js"]

docker-compose:

version: '3.9'

services:
  backend:
    build:
      context: .
      dockerfile: apps/backend/Dockerfile
    ports:
      - "3333:3333"
    networks:
      - omnimart
    environment:
      - NODE_ENV=production

  frontend:
    build:
      context: .
      dockerfile: apps/frontend/Dockerfile
    ports:
      - "3000:3000"
    networks:
      - omnimart
    environment:
      - NODE_ENV=production
    depends_on:
      - backend

networks:
  omnimart:
    driver: bridge

dockerignore:

# Git
.git
.gitignore

# Docker
.dockerignore
Dockerfile*

# Node / pnpm
node_modules
apps/**/node_modules
packages/**/node_modules
.pnpm-store/

# Build artifacts
.next
dist

# Env files
.env
.env*
*.log

# IDE config
.vscode