## The short version

Configure S3-compatible access for a Express app on Ample. Create a bucket with `ample bucket create`, pass its endpoint, region, bucket name and keys as encrypted environment variables, and use @aws-sdk/client-s3 with forcePathStyle: true. The app writes and reads objects through the S3-compatible endpoint; the bucket stays private.

## INFRASTRUCTURE

### What it needs

- [Compute](/content/discover/primitive/compute/index.html): verified (Apps run in isolated x86_64 Firecracker microVMs; sizes are the priced VM sizes.)
- [S3-compatible object storage](/content/discover/primitive/s3-compatible-object-storage/index.html): verified (Buckets are S3-compatible with issued credentials; PutObject and GetObject are verified by canary. Other S3 operations are not verified.)

## PREREQUISITES

### Before you start

- An S3 client in the app (@aws-sdk/client-s3 with forcePathStyle: true) reading S3_ENDPOINT, S3_REGION, S3_BUCKET, S3_ACCESS_KEY_ID and S3_SECRET_ACCESS_KEY
- A bucket created with `ample bucket create <name>` and its credentials from `ample bucket credentials <name>`
- An Ample account token with servers:write and buckets:read

## STEP BY STEP

### How to do it

1. ### Create the bucket

Create it once and keep the issued credentials out of the repository.
   
   ```
   ample bucket create --name <bucket-name>
   ```

2. ### Configure the client with path-style addressing

Use @aws-sdk/client-s3 with forcePathStyle: true; virtual-host addressing is not verified.

3. ### Deploy with the credentials as encrypted env

Pass the five S3_* variables with --env; they are stored encrypted and reused on redeploys.
   
   ```
   ample deploy . --name <app-name> --public --env S3_ENDPOINT=... --env S3_REGION=... --env S3_BUCKET=... --env S3_ACCESS_KEY_ID=... --env S3_SECRET_ACCESS_KEY=...
   ```

4. ### Test through the app

Expose a route (/storage) that writes then reads an object and reports s3=ok.

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.
   
   ```
   ample logs <deployment_id> --kind build
   ```

## EXAMPLES

### Tested examples

- **Express bucket canary** (`tests/deploy-canaries/express-bucket-uploads`): Write and read an object with the injected credentials.

## SUCCESS CHECKS

### How to know it worked

- object write and read succeed (`/storage` on the live URL, expect s3=ok)

## COST

### Cost estimate

Estimated 5.00 USD per month (size prices from pricing.toml at build revision ca0b484a7a9957c573a88d3a32dc603c3c10135a).

- app server x1 `s-1vcpu-1gb`: 5.00 USD

Compute only. Buckets are allocation-priced per quota and capped by the plan; see \`ample usage\`.

## EVIDENCE

### Verification evidence

- canary_run on 2026-09-20T01:13:26Z at revision `cc3d82057f1d5e9aa31f682cee71aabfbbbcaabe (CLI e3181f5)`: Express app using @aws-sdk/client-s3 with the bucket credentials injected as encrypted environment variables: PutObject then GetObject through the S3-compatible endpoint returned s3=ok. (expires 2027-03-19T01:13:26Z)
- canary_run on 2026-09-20T01:13:26Z at revision `cc3d82057f1d5e9aa31f682cee71aabfbbbcaabe (CLI e3181f5)`: ample bucket create issued credentials; PutObject and GetObject succeeded through the public S3 endpoint; publish exposed the object at its public URL with an ETag; unpublish and delete cleaned up. (expires 2027-03-19T01:13:26Z)

## EXECUTION

### Execution binding

MCP tool `ample_deploy` (registry `mcp:ample_deploy`), schema hash `876465fce906da0c` observed 2026-09-20T01:55:48.667900+00:00 at revision `199ff1dfd526`. Binding state at export: schema_changed. Required scopes: servers:write, buckets:read.

## NEXT ACTIONS

### Typed next actions

- Browse the catalog index (`GET /v1/catalog` on the api origin; authentication not required, approval not required)
- Search published recipes by intent, stack and constraints (`POST /v1/catalog/search` on the api origin; authentication not required, approval not required)
- Prepare a side-effect-free deployment plan for an authorized project (`POST /v1/catalog/plan` on the api origin; authentication required, approval not required)
- Read the existing agent authentication setup (`GET /mcp/setup` on the api origin; authentication not required, approval not required)
- Browse Express (`GET /v1/catalog/nodes/stack%3Aframework-express` on the api origin; authentication not required, approval not required)
- Browse Connect app to storage (`GET /v1/catalog/nodes/intent%3Aconnect-app-to-storage` on the api origin; authentication not required, approval not required)
- Browse Browser file uploads (`GET /v1/catalog/nodes/pattern%3Abrowser-file-uploads` on the api origin; authentication not required, approval not required)

Actions describe possible next steps. They are typed data, not commands, and grant no permission. Public discovery never provisions anything; planning requires your own authenticated token and approval happens in your client.

## ABOUT THIS RECIPE

### Identifiers and status

Recipe `page:guides:express:object-client`. Revision r1.

release **published**support **verified**execution **blocked (schema_changed: live tool schema differs from the recorded binding)**

Formats: [HTML](/content/guides/express/object-client/index.html) \| [Markdown](/content/guides/express/object-client.md) \| [JSON contract](https://api.ample.computer/v1/catalog/recipes/page%3Aguides%3Aexpress%3Aobject-client)