Turborepo

Turborepo is a build system for JavaScript and TypeScript monorepos. This guide shows how to set up an Encore application within a Turborepo monorepo that depends on shared packages requiring compilation.

Overview

When using Encore in a Turborepo monorepo, you may have shared packages (like utility libraries or shared types) that need to be built before the Encore app can use them. Since Encore parses your application on startup, these dependencies must be compiled first.

This guide covers two scenarios:

• Local development: Use Turborepo to build dependencies before running encore run
• Deployment: Use Encore's prebuild hook to automatically build dependencies when deploying via Encore Cloud or exporting a Docker image

Project structure

A typical Turborepo setup with Encore looks like this:

my-turborepo/
├── apps/
│   └── backend/           # Encore application
│       ├── encore.app
│       ├── package.json
│       ├── tsconfig.json
│       └── article/
│           └── article.ts
├── packages/
│   └── shared/            # Shared library requiring build
│       ├── package.json
│       ├── tsconfig.json
│       ├── src/
│       │   └── index.ts
│       └── dist/          # Built output
│           └── index.js
├── turbo.json
├── package.json
└── package-lock.json

Configuration

Root package.json

Configure npm workspaces to include your apps and packages:

{
  "name": "my-turborepo",
  "private": true,
  "packageManager": "[email protected]",
  "scripts": {
    "build": "turbo run build",
    "dev": "turbo run dev"
  },
  "devDependencies": {
    "turbo": "^2.0.0",
    "typescript": "^5.0.0"
  },
  "workspaces": [
    "apps/*",
    "packages/*"
  ]
}

The packageManager field is required by Turborepo. Adjust the version to match your installed npm version (run npm --version to check).

turbo.json

Configure Turborepo's build pipeline in the root turbo.json. The @repo/backend#dev task depends on the shared package being built first:

{
  "$schema": "https://turbo.build/schema.json",
  "tasks": {
    "build": {
      "dependsOn": ["^build"],
      "outputs": ["dist/**"]
    },
    "@repo/backend#dev": {
      "dependsOn": ["@repo/shared#build"],
      "cache": false,
      "persistent": true
    },
    "dev": {
      "cache": false,
      "persistent": true
    }
  }
}

The @repo/backend#dev task configuration ensures the shared package is built before running encore run in local development.

Shared package

Your shared package needs to compile TypeScript to JavaScript and expose the built output:

packages/shared/package.json:

{
  "name": "@repo/shared",
  "version": "1.0.0",
  "private": true,
  "type": "module",
  "main": "./dist/index.js",
  "types": "./dist/index.d.ts",
  "exports": {
    ".": {
      "types": "./dist/index.d.ts",
      "default": "./dist/index.js"
    }
  },
  "scripts": {
    "build": "tsc"
  },
  "devDependencies": {
    "typescript": "^5.0.0"
  }
}

packages/shared/tsconfig.json:

{
  "compilerOptions": {
    "outDir": "dist",
    "rootDir": "src",
    "moduleResolution": "bundler",
    "module": "ES2022",
    "target": "ES2022",
    "declaration": true
  },
  "include": ["src"],
  "exclude": ["node_modules", "dist"]
}

packages/shared/src/index.ts:

// Types shared between frontend and backend
export interface Article {
  slug: string;
  title: string;
  preview: string;
}

export interface CreateArticleRequest {
  title: string;
  content: string;
}

// Utility functions
export function slugify(text: string): string {
  return text
    .toLowerCase()
    .trim()
    .replace(/[^\w\s-]/g, "")
    .replace(/\s+/g, "-");
}

export function truncate(text: string, maxLength: number): string {
  if (text.length <= maxLength) return text;
  return text.slice(0, maxLength - 3) + "...";
}

Encore application

The Encore app needs two key configurations:

1. encore.app - Use the prebuild hook to build dependencies during deployment
2. package.json - Declare the dependency on the shared package

To create the Encore app, run encore app init --lang ts from the apps/backend directory. Then add the prebuild hook to the generated encore.app file:

apps/backend/encore.app:

{
    "id": "generated-id",
    "lang": "typescript",
    "build": {
        "hooks": {
            "prebuild": "npx turbo build --filter=@repo/backend^..."
        }
    }
}

The prebuild hook runs when deploying via Encore Cloud or when exporting a Docker image with the Encore CLI. The filter @repo/backend^... tells Turborepo to build all dependencies of @repo/backend. The ^ excludes the backend itself, building only its dependencies.

apps/backend/package.json:

{
  "name": "@repo/backend",
  "version": "1.0.0",
  "type": "module",
  "scripts": {
    "dev": "encore run"
  },
  "dependencies": {
    "@repo/shared": "*",
    "encore.dev": "latest"
  }
}

Using the shared package

With this setup, you can import from your shared package in your Encore services:

apps/backend/article/article.ts:

import { api } from "encore.dev/api";
import type { Article, CreateArticleRequest } from "@repo/shared";
import { slugify, truncate } from "@repo/shared";

export const create = api(
  { expose: true, method: "POST", path: "/article" },
  async ({ title, content }: CreateArticleRequest): Promise<Article> => {
    return {
      slug: slugify(title),
      title: title,
      preview: truncate(content, 100),
    };
  },
);

Running the application

Installation

First, install all dependencies from the monorepo root:

$ npm install

This installs dependencies for all workspaces, including Turborepo.

Local development

For local development, you need to build the shared packages before running encore run. From the monorepo root:

$ npx turbo run build
$ cd apps/backend && encore run

Or use Turborepo's dev task which handles the dependency ordering:

$ npx turbo run dev --filter=@repo/backend

The turbo.json configuration ensures @repo/shared is built before the backend's dev task runs.

Deployment

When deploying via Encore Cloud or exporting a Docker image, the prebuild hook in encore.app automatically runs the Turborepo build pipeline.

Key points

• Local development: Run npx turbo run build before encore run, or use npx turbo run dev --filter=@repo/backend to handle dependency ordering automatically
• Prebuild hook: The prebuild hook in encore.app runs during deployment (Encore Cloud) or Docker export, not during local development
• Turborepo filter: Using --filter=@repo/backend^... builds only the dependencies of the backend (the ^ excludes the package itself)