Elastic Beanstalk Node.js Deployment

Overview

AWS Elastic Beanstalk automates Node.js application deployment but has specific behaviors around dependency installation that can cause issues, especially with monorepos. Understanding when EB installs dependencies vs when it skips installation is critical for successful deployments.

Core principle: Choose between letting EB install dependencies (smaller packages, slower) or bundling node_modules (larger packages, more reliable).

When to Use

Use when:

• Deploying Node.js applications to AWS Elastic Beanstalk
• Encountering "Cannot find package" errors during deployment
• Working with monorepo workspace packages
• Need reliable deployments without npm registry dependencies
• Deploying applications with private packages

Don't use for:

• Non-AWS deployments
• Docker-based deployments (different dependency strategy)
• Simple apps with only public npm packages (standard approach works fine)

Official AWS Documentation

Reference: https://docs.aws.amazon.com/elasticbeanstalk/latest/dg/nodejs-platform-dependencies.html

Quick Reference: EB Dependency Installation Behavior

Condition	EB Action	npm Command
package.json exists, NO node_modules/	Installs dependencies	npm install --omit=dev (npm 7+)
node_modules/ directory present	Skips installation	None - uses bundled modules

Deployment Strategies

Strategy 1: Let EB Install Dependencies (Standard)

Best for: Simple apps, all packages in npm registry, no monorepo

# GitHub Actions workflow
- name: Build application
  run: npm run build

- name: Create deployment package
  run: |
    zip -r app.zip \
      dist/ \
      package.json \
      package-lock.json \
      .ebextensions/

Pros:

• Smaller deployment packages (5-10MB typical)
• Consistent with npm ecosystem
• Uses platform's npm version

Cons:

• Slower deployments (installs on every deploy)
• Requires all packages in npm registry
• Can fail with network/registry issues

Strategy 2: Bundle node_modules (AWS Recommended for Special Cases)

Best for: Monorepos, private packages, reliability requirements

AWS official quote: "Bundle node_modules to bypass potential npm registry installation issues."

# GitHub Actions workflow
- name: Install production dependencies
  run: npm install --omit=dev

- name: Create deployment package
  run: |
    zip -r app.zip \
      dist/ \
      package.json \
      node_modules/ \
      .ebextensions/

Pros:

• Bypasses npm registry issues
• Faster deployments (no install phase)
• Works with workspace packages
• Reliable and predictable

Cons:

• Larger packages (50-100MB typical)
• Must ensure platform-compatible binaries

Monorepo / Workspace Package Strategy

The Problem

Running npm ci --production inside a monorepo workspace:

• Creates symlinks to workspace packages (not actual files)
• Results in incomplete node_modules (~3MB instead of ~50MB)
• Causes "Cannot find package" errors during EB deployment

Example error:

Error: Cannot find module '@prpm/types'

The Solution: Clean Context Installation

Install dependencies outside the workspace context to get real files instead of symlinks:

- name: Create standalone package.json
  run: |
    mkdir -p /tmp/clean-install
    cd /tmp/clean-install

    # Copy package.json and replace workspace refs with file paths
    cp $GITHUB_WORKSPACE/packages/app/package.json .
    jq --arg workspace "$GITHUB_WORKSPACE" \
      '.dependencies["@workspace/pkg"] = "file:\($workspace)/packages/pkg"' \
      package.json > package.json.tmp
    mv package.json.tmp package.json

- name: Install dependencies (outside workspace)
  run: |
    cd /tmp/clean-install
    npm install --omit=dev --legacy-peer-deps

    # Verify critical packages (real directories, not symlinks)
    test -d node_modules/pg || exit 1
    test -d node_modules/@workspace/pkg/dist || exit 1

- name: Copy to deployment location
  run: |
    rm -rf packages/app/node_modules
    cp -r /tmp/clean-install/node_modules packages/app/

Key steps:

1. Install outside workspace context
2. Convert workspace dependencies to file: references
3. Verify packages are real directories (not symlinks)
4. Bundle complete node_modules in deployment

Environment Configuration

Override Production Install Mode

Set in Beanstalk console:

NPM_USE_PRODUCTION=false

Specify Node.js Version

In package.json:

{
  "engines": {
    "node": "20.x"
  }
}

Note: Version range feature not available on Amazon Linux 2023

Container Commands for Migrations

When bundling node_modules, migrations can run immediately:

# .ebextensions/migrations.config
container_commands:
  01_run_migrations:
    command: npm run migrate
    leader_only: true

Why this works with bundled approach:

1. EB extracts deployment to /var/app/staging/
2. node_modules/ already present (bundled)
3. EB skips npm install step
4. Migrations run with all dependencies available

Common Issues and Solutions

Issue: "Cannot find package 'X'"

Symptoms:

Error: Cannot find module 'pg'
Error: Cannot find module '@prpm/types'

Cause: Package not installed or symlinked

Solution:

# Verify package exists as real directory
ls -la node_modules/pg
file node_modules/@prpm/types  # Should show "directory", not "symbolic link"

# If symlink, use clean context installation (see above)

Issue: "npm install fails with workspace package not found"

Symptoms:

npm ERR! Could not resolve dependency: @workspace/package

Cause: Workspace package not in npm registry

Solution: Use bundled node_modules approach with clean context installation

Issue: Binary compatibility errors

Symptoms:

Error: The module was compiled against a different Node.js version

Cause: Native modules compiled for macOS/Windows, deployed to Linux

Solution:

• Install dependencies in Linux environment (Docker, GitHub Actions with ubuntu-latest)
• Or use --platform=linux flag for specific packages

Issue: Deployment package too large (>500MB)

Cause: Dev dependencies or unnecessary files included

Solution:

# Use --omit=dev flag
npm install --omit=dev

# Exclude unnecessary files
zip -r app.zip dist/ package.json node_modules/ .ebextensions/ \
  -x "*.cache/*" "*.test.js" "*.spec.js"

# Use .ebignore file
echo "*.test.js" >> .ebignore
echo "*.spec.js" >> .ebignore

Verification Steps

Before deploying, always verify:

# 1. Check node_modules size (should be 50MB+ for typical apps)
du -sh node_modules
# Expected: 50M-100M (if bundled)
# Red flag: 3M-5M (likely symlinks)

# 2. Verify critical packages exist
ls -la node_modules/pg
ls -la node_modules/fastify
ls -la node_modules/@your-workspace/package

# 3. Check for symlinks (should see real directories)
file node_modules/@your-workspace/package
# Expected: "directory"
# Red flag: "symbolic link to ../../packages/your-package"

# 4. Verify dist directories for workspace packages
test -d node_modules/@your-workspace/package/dist || echo "ERROR: dist missing"

# 5. Test the deployment package locally
unzip -q app.zip -d /tmp/test-deploy
cd /tmp/test-deploy
node dist/index.js  # Should start without errors

Best Practices

1. Always Include package-lock.json

✅ Do: Include package-lock.json for reproducible builds

zip -r app.zip dist/ package.json package-lock.json node_modules/

❌ Don't: Omit lock file or use only package.json

2. Verify Deployment Package

# Inspect before uploading
unzip -l app.zip | grep node_modules | head -20

# Check size
ls -lh app.zip
# Should be: 50-100MB (bundled) or 5-10MB (unbundled)

3. Test Locally First

# Extract and test the exact deployment package
unzip app.zip -d /tmp/deployment-test
cd /tmp/deployment-test
npm start  # Should work without any npm install

4. Monitor First Deployment

When switching from unbundled to bundled (or vice versa):

• Watch EB console logs carefully
• Verify application starts successfully
• Check for dependency-related errors
• Have rollback plan ready

5. Keep Deployment Packages

Save successful deployment packages for rollback:

aws s3 cp app.zip s3://my-bucket/deployments/app-$(date +%Y%m%d-%H%M%S).zip

Decision Tree: Which Strategy to Use?

Does your app use monorepo workspace packages?
├─ Yes → Use bundled node_modules (Strategy 2)
│   └─ Install in clean context (outside workspace)
└─ No → Do you need maximum reliability?
    ├─ Yes → Use bundled node_modules (Strategy 2)
    │   └─ Faster deploys, no registry issues
    └─ No → Are all packages in public npm registry?
        ├─ Yes → Let EB install (Strategy 1)
        │   └─ Smaller packages, standard approach
        └─ No (private packages) → Use bundled node_modules (Strategy 2)

Real-World Example: PRPM Registry

This project uses bundled node_modules approach because:

• @prpm/types is a workspace package (not in npm registry)
• Requires reliable deployments without registry dependencies
• Migrations need pg package available immediately
• Speed and predictability are critical

See .github/workflows/deploy-registry.yml for full implementation.

Additional Resources

• AWS EB Node.js Platform
• npm workspaces documentation
• Elastic Beanstalk container commands