# Migrate Backblaze B2 S3 bucket: Public media library

## Summary

Move object storage from Backblaze B2 S3 bucket to Ample, one component at a time. Destination verified on Ample: an object written to a published bucket with an immutable Cache-Control header, a mapping row, and the CDN URL serving it publicly. Source procedure: Inventory the bucket with `rclone size` or the B2 dashboard. Not migrated automatically: B2 file versions, lifecycle rules, and application-key restrictions are not migrated. Cutover: Switch the app's S3_* environment to the Ample bucket with a redeploy, verify reads and writes, keep B2 read-only until confirmed. Rollback: keep the source untouched until you confirm; nothing at the source is changed or deleted by this guide.

## Infrastructure requirements

- [S3-compatible object storage](/discover/primitive/s3-compatible-object-storage): verified (Buckets are S3-compatible with issued credentials; PutObject and GetObject are verified by canary. Other S3 operations are not verified.)

## Prerequisites

- Authorized access to the Backblaze B2 S3 bucket source and its export tooling
- An inventory of every component in scope and out of scope
- A validated backup or copy before any cutover
- An Ample account token with servers:write, buckets:write

## Exact tested configuration

- template: `node-22`
- runtime: `node`
- size: `s-1vcpu-1gb`
- install: `npm install`
- build: `npm run build --if-present`
- start: `npm run start`

## Steps

1. **Inventory the source.** List what Backblaze B2 S3 bucket provides beyond the component you are moving. Out of scope here: B2 file versions, lifecycle rules, and application-key restrictions are not migrated.
2. **Source step 1.** Inventory the bucket with `rclone size` or the B2 dashboard
3. **Source step 2.** Copy objects with `rclone sync` from the B2 S3-compatible endpoint to the Ample bucket endpoint using the issued credentials (path-style)
4. **Source step 3.** Verify a sample of objects by size and checksum after the copy
5. **Create the destination bucket and copy.** Create the bucket, copy with rclone or the S3 CLI in path-style mode using the issued credentials, then pass the credentials to the app as encrypted S3_* variables.
   
   ```
   ample bucket create --name <bucket-name>
   ```
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/public-media-library).
7. **Cut over.** Switch the app's S3_* environment to the Ample bucket with a redeploy, verify reads and writes, keep B2 read-only until confirmed.
8. **Rollback.** Point DNS or configuration back to the source. The source was never modified; deletion is a separate, user-executed step after validation.

## Tested examples

- **Express pattern fixture (destination)** (tests/deploy-canaries/express-patterns): Verified destination basis: public media library.

## Success checks

- destination app responds on its public URL (`/` on the live URL, expect ample canary express patterns)
- public-media-library check from the destination example (`/p/public-media-library` on the live URL, expect see the pattern fixture checks)
- data or object counts and checksums match the source

## Limitations

- Documentation only: nothing is executed automatically and no execution binding is offered.
- The source-side procedure is documented from Backblaze B2 S3 bucket'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: B2 file versions, lifecycle rules, and application-key restrictions are not migrated.
- 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.

## Cost estimate

Estimated 5.00 USD per month (size prices from pricing.toml at build revision a1b8c38919e59cd035ebabaced73cf84ece24371).
- app server x1 `s-1vcpu-1gb`: 5.00 USD

Destination always-on monthly price of the tested sizes; apps auto-pause when idle. Source costs are unknown to Ample.

## Verification evidence

- canary_run on 2026-09-21T02:34:39Z at revision `1d28ae0-dirty (CLI 0.1.21)`: Destination side verified: the Express pattern fixture deployed on Ample (npm install, npm run build --if-present, npm run start on the node-22 template) and its checks passed (an object written to a published bucket with an immutable Cache-Control header, a mapping row, and the CDN URL serving it publicly). The source-side export from Backblaze B2 S3 bucket is documented from the vendor's standard tooling and was not executed by this catalog's evidence. (expires 2027-03-20T02:34:39Z)

Last verified: 2026-09-21T02:34:39Z

## Execution binding

No execution binding. This recipe is documentation only; nothing is executed automatically.