/cloudflare-deploy

Best Practices

1. Use Selective Worker-First Routing

Instead of run_worker_first = true, use array patterns:

{
  "assets": {
    "run_worker_first": [
      "/api/*",           // API routes
      "/admin/*",         // Admin area
      "!/admin/assets/*"  // Except admin assets
    ]
  }
}

Benefits:

• Reduces Worker invocations
• Lowers costs
• Improves asset delivery performance

2. Leverage Navigation Request Optimization

For SPAs, use compatibility_date = "2025-04-01" or later:

{
  "compatibility_date": "2025-04-01",
  "assets": {
    "not_found_handling": "single-page-application"
  }
}

Navigation requests skip Worker invocation, reducing costs.

3. Type Safety with Bindings

Always type your environment:

interface Env {
  ASSETS: Fetcher;
}

Common Errors

"Asset not found"

Cause: Asset not in assets directory, wrong path, or assets not deployed
Solution: Verify asset exists, check path case-sensitivity, redeploy if needed

"Worker not invoked for asset"

Cause: Asset served directly, run_worker_first not configured
Solution: Configure run_worker_first patterns to include asset routes (see configuration.md:66-106)

"429 Too Many Requests on free tier"

Cause: run_worker_first patterns invoke Worker for many requests, hitting free tier limits (100k req/day)
Solution: Use more selective patterns with negative exclusions, or upgrade to paid plan

"Smart Placement increases latency"

Cause: run_worker_first=true + Smart Placement routes all requests through single smart-placed location
Solution: Use selective patterns (array syntax) or disable Smart Placement for asset-heavy apps

"CF-Cache-Status header unreliable"

Cause: Header is probabilistically added for privacy reasons
Solution: Don't rely on CF-Cache-Status for critical routing logic. Use other signals (ETag, age).

"JWT expired during deployment"

Cause: Large asset deployments exceed JWT token lifetime
Solution: Update to Wrangler 4.34.0+ (automatic token refresh), or reduce asset count

"Cannot use 'assets' with 'site'"

Cause: Legacy site config conflicts with new assets config
Solution: Migrate from site to assets (see configuration.md). Remove site key from wrangler.jsonc.

"Assets not updating after deployment"

Cause: Browser or CDN cache serving old assets
Solution:

• Hard refresh browser (Cmd+Shift+R / Ctrl+F5)
• Use cache-busting (hashed filenames)
• Verify deployment completed: wrangler tail

Limits

Version Requirements

Performance Tips

1. Use Hashed Filenames

Enable long-term caching with content-hashed filenames:

app.a3b2c1d4.js
styles.e5f6g7h8.css

Most bundlers (Vite, Webpack, Parcel) do this automatically.

2. Minimize Worker Invocations

Serve assets directly when possible:

{
  "assets": {
    // Only invoke Worker for dynamic routes
    "run_worker_first": ["/api/*", "/auth/*"]
  }
}

3. Leverage Browser Cache

Set appropriate Cache-Control headers:

// Versioned assets
'Cache-Control': 'public, max-age=31536000, immutable'

// HTML (revalidate often)
'Cache-Control': 'public, max-age=0, must-revalidate'

See patterns.md:169-189 for implementation.

4. Use .assetsignore

Reduce upload time by excluding unnecessary files:

*.map
*.md
.DS_Store
node_modules/

See configuration.md:107-126 for details.