page:guides:fastapi:private file access

Enforce Private-File Authorization for FastAPI

Private file access for a FastAPI app on Ample. Verified on FastAPI: a role-to-document access model with negative tests (401, 403) and an authorized private-bucket round-trip (private=ok).

Build and start: pip install into .ample/python from requirements.txt, then uvicorn from run.py reading PORT on the python-3.12 template.

Resource Requirements

• primitive:compute
• primitive:postgres
• primitive:s3-compatible-object-storage

Infrastructure Requirements

1. Compute
   • verified
   • Apps run in isolated x86_64 Firecracker microVMs that auto-pause when idle and wake on request; sizes are the priced VM sizes.
2. Postgres
   • verified
   • Managed PostgreSQL 16 runs in its own microVM and is auto-provisioned when an app needs a database and no DATABASE_URL is supplied.
3. 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

1. A FastAPI project (pip install into .ample/python from requirements.txt, then uvicorn from run.py reading PORT on the python-3.12 template)
2. A PostgreSQL driver reading DATABASE_URL at runtime
3. A bucket from ample bucket create with credentials passed as encrypted S3_* environment variables
4. An Ample account token with servers:write, databases:read, buckets:read

Workflow Steps

• Build and start pip install into .ample/python from requirements.txt, then uvicorn from run.py reading PORT on the python-3.12 template; the server must bind 0.0.0.0 on PORT.
• Create the bucket and pass its credentials ample deploy . --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=...
• Authorize before touching storage Return 401 for unauthenticated requests and 403 for the wrong role; keep the bucket unpublished and stream objects through the app.
• Verify Fetch the live URL and /p/private-document-library on the example; on failure read the build and runtime logs. ample logs --kind build

Examples

• FastAPI pattern fixture Verified private file access on FastAPI. sourceRef: tests/deploy-canaries/fastapi-patterns

Success Checks

1. app responds on its public URL
   • kind: http_get
   • path: /
   • expect: ample canary fastapi patterns
2. private-document-library check from the example
   • kind: http_get
   • path: /p/private-document-library
   • expect: see the pattern fixture checks

Limitations

• Verified on the python-3.12 template at s-1vcpu-1gb; other sizes and FastAPI major versions are not verified.
• Region, compliance attestations, and request-duration limits are unknown and not claimed.
• Managed PostgreSQL 16 only; extensions, connection limits, and backup or restore procedures are not verified.
• PutObject and GetObject with path-style addressing are verified; other S3 operations are not.

Cost Estimate

• Currency: USD

• Monthly Amount: 10.0

• Basis: size prices from pricing.toml (loaded by the API) at build revision 1ac5595375130d45290090e82ed0f554ccd45405-dirty

• Components:

  • app server
    • size: s-1vcpu-1gb
    • quantity: 1.0
    • monthlyAmount: 5.0
  • managed PostgreSQL database
    • size: s-1vcpu-1gb
    • quantity: 1.0
    • monthlyAmount: 5.0

• Note: Always-on monthly price of the tested sizes; apps auto-pause when idle. Buckets are allocation-priced per quota and not included.

Evidence Summary

• Canary Run Summary: FastAPI pattern fixture deployed on Ample; for this guide: a role-to-document access model with negative tests (401, 403) and an authorized private-bucket round-trip (private=ok).

Last Verified At

• 2026-09-21T01:14:18Z

Next Actions

1. Browse the catalog index
2. Search published recipes by intent, stack, and constraints
3. Prepare a side-effect-free deployment plan for an authorized project
4. Read the existing agent authentication setup
5. Browse FastAPI
6. Browse Connect app to storage
7. Browse Private document library