Deliver public assets through CDN for Express

Deliver public assets for an Express app through the Ample CDN. Publish a bucket with ample bucket publish, upload versioned assets with long-lived Cache-Control headers, and reference the CDN URL (https://cdn.//) from your pages. The CDN serves bucket objects; the app's own responses are still served by the app.

Representative Queries

• Deliver public assets through CDN for Express
• Where can I host Deliver public assets through CDN built with Express?
• I need a public-origin configuration, versioned asset build and observable cache behavior.

Prerequisites

• A bucket created with ample bucket create and published with ample bucket publish (its public URL is the CDN base)
• An S3 client in the app to upload assets under versioned keys
• An Ample account token with servers:write and buckets:write

Steps to Deliver Assets

1. Publish the bucket
   Publishing makes objects readable at the CDN URL; keep private data in a separate, unpublished bucket.
   Command: ample bucket publish

2. Upload versioned assets
   Use keys such as assets//file and set Cache-Control: public, max-age=31536000, immutable; change the version to invalidate.

3. Reference the CDN URL
   Pass S3_PUBLIC_URL to the app and build asset URLs from it.
   Command: ample deploy . --name <app-name> --public --env S3_PUBLIC_URL=... --env S3_ENDPOINT=... --env S3_REGION=... --env S3_BUCKET=... --env S3_ACCESS_KEY_ID=... --env S3_SECRET_ACCESS_KEY=...

4. Verify delivery
   Fetch /asset-url for the asset URL, then fetch that URL: the CDN must return the asset.

5. Verify
   Fetch the live URL and run the success checks below. On failure read the build log, then the runtime log, fix the cause and deploy again; do not blind-retry.
   Command: ample logs <app-name> --kind build

Examples

• Express CDN assets canary
  Versioned asset uploaded to a published bucket and served from the CDN URL. Source Reference: tests/deploy-canaries/express-cdn-assets

Success Checks

• Asset URL resolves through the CDN
  Kind: http_get
  Path: /asset-url
  Expect: https://cdn.

Limitations

• Verified on the node-22 template at s-1vcpu-1gb; other templates and sizes are not verified by this recipe.
• Region, compliance attestations and request-duration limits are unknown and not claimed.
• Apps auto-pause when idle and wake on the next request; always-on is an operator setting, not a plan feature.
• PutObject and GetObject with path-style addressing are verified; multipart upload, listing, presigned URLs and lifecycle rules are not verified.
• Bucket credentials are passed as encrypted environment variables; the catalog never creates the bucket for you (use ample bucket create).
• Storage is allocation-priced per bucket quota and capped by the account plan; the estimate below covers compute only.
• The CDN serves objects from a published bucket only; it does not front the app's own responses.
• Cache rules, purge and TTL control are not verified; the fixture sets Cache-Control on upload and versions asset keys instead.

Cost Estimate

• Currency: USD
  Monthly Amount: 5.0
  Note: Compute only. Buckets are allocation-priced per quota and capped by the plan; see ample usage.

Evidence Summary

• Canary Run
  Summary: Express app uploaded a versioned, immutable-cached asset to a published bucket at startup; the CDN URL it returned served the asset publicly. Observed At: 2026-09-20T01:13:26Z

• Canary Run
  Summary: ample bucket create issued credentials; PutObject and GetObject succeeded through the public S3 endpoint; publish exposed the object through the CDN host with an ETag; unpublish and delete cleaned up. Observed At: 2026-09-20T01:13:26Z

Next Actions

• Browse the catalog index
  Method: GET
  Relative Path: /v1/catalog

• Search published recipes
  Method: POST
  Relative Path: /v1/catalog/search
  Parameters: {"body":{"limit":5,"query":"Deliver public assets through CDN for Express"}}

• Prepare a deployment plan
  Method: POST
  Relative Path: /v1/catalog/plan
  Parameters: {"body":{"inputs":{},"projectId":"","recipeId":"page:guides:express:cdn-assets","recipeRevision":"r1"}}

• Read the existing authentication setup
  Method: GET
  Relative Path: /mcp/setup

• Browse Express
  Method: GET
  Relative Path: /v1/catalog/nodes/stack%3Aframework-express

• Browse Add CDN
  Method: GET
  Relative Path: /v1/catalog/nodes/intent%3Aadd-cdn

• Browse Versioned static assets
  Method: GET
  Relative Path: /v1/catalog/nodes/pattern%3Aversioned-static-assets