## The short version

Configure S3-compatible access for a FastAPI app on Ample. Create a bucket with `ample bucket create`, pass its endpoint, region, bucket name and keys as encrypted environment variables, and use boto3 with Config(s3={'addressing_style': 'path'}). The app writes and reads objects through the S3-compatible endpoint; the bucket stays private.

---

## 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.)

---

## Before you start

- An S3 client in the app (boto3 with Config(s3={'addressing_style': 'path'})) 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

---

## How to do it

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

2.  **Configure the client with path-style addressing**  
    Use boto3 with Config(s3={'addressing_style': 'path'}); 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.
    
    ```bash
    ample deploy . --name <app-name> --public --start "python3 run.py" --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.
    
    ```bash
    ample logs <deployment_id> --kind build
    ```

---

## Tested examples

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

---

## How to know it worked

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

---

## 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`.

---

## Verification evidence

- canary_run on 2026-09-20T01:13:26Z at revision `cc3d82057f1d5e9aa31f682cee71aabfbbbcaabe (CLI e3181f5)`: FastAPI app using boto3 (path-style addressing) with injected bucket credentials: put_object then get_object 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 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.

---

## 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 FastAPI (`GET /v1/catalog/nodes/stack%3Aframework-fastapi` 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)