## Migrate CloudFront distribution: Origin cache refresh

Move CDN delivery from CloudFront distribution to Ample, one component at a time. Destination verified on Ample: a no-cache object overwritten in the published bucket and the CDN URL serving the new content on the next fetch (refresh=ok before=v1 after=v2), verified by the app fetching its own public URL.

### Source procedure
- Record the distribution's origins, cache behaviors, TTLs and the object keys the app references.
- Not migrated automatically: CloudFront cache behaviors, Lambda@Edge and CloudFront Functions, signed URLs and custom TTLs are not migrated; Ample verifies delivery of published bucket objects only.

### Cutover
- Redeploy the app with the new asset base URL, verify delivery from the CDN URL, keep the distribution until confirmed, then disable it.

### Rollback
- Keep the source untouched until you confirm; nothing at the source is changed or deleted by this guide.

### Workflow Steps
1. **Inventory the source**: List what CloudFront distribution provides beyond the component you are moving. Out of scope here: CloudFront cache behaviors, Lambda@Edge and CloudFront Functions, signed URLs and custom TTLs are not migrated; Ample verifies delivery of published bucket objects only.
2. **Source step 1**: Record the distribution's origins, cache behaviors, TTLs and the object keys the app references.
3. **Source step 2**: Copy the public assets into a published Ample bucket under versioned keys with immutable Cache-Control.
4. **Source step 3**: Update the app to build asset URLs from the Ample public URL.
5. **Publish the destination bucket**: Create and publish the asset bucket, upload versioned assets with immutable Cache-Control, and point the app at the public URL.
   - Command: `ample bucket publish`
6. **Validate before cutover**: Run the app's own checks and, for data, compare counts and checksums; the example checks are the pattern self-tests (/p/origin-cache-refresh).
7. **Cut over**: Redeploy the app with the new asset base URL, verify delivery from the CDN URL, keep the distribution until confirmed, then disable it.
8. **Rollback**: Point DNS or configuration back to the source. The source was never modified; deletion is a separate, user-executed step after validation.

### Success Checks
- Destination app responds on its public URL: It should return `ample canary next js patterns`.
- **Origin-cache-refresh** check from the destination example: Expect to see the pattern fixture checks.
- Data or object counts and checksums match the source: This requires operator comparison before cutover.

### Limitations
- Documentation only: nothing is executed automatically and no execution binding is offered.
- The source-side procedure is documented from CloudFront distribution's standard tooling and was not executed in this catalog's evidence; the destination side was verified with the pattern fixture.
- No full source-product parity is claimed: CloudFront cache behaviors, Lambda@Edge and CloudFront Functions, signed URLs and custom TTLs are not migrated; Ample verifies the delivery of published bucket objects only. 
- Verified on the node-22 template at s-1vcpu-1gb; region, compliance and request-duration limits are unknown. 
- PutObject and GetObject with path-style addressing are verified; bulk copy tooling and other S3 operations are not.