Host REST API with FastAPI: Stored Input and Output Artifacts

Deploy a REST API built with FastAPI on Ample using the generated downloads pattern. Compute runs the app in an isolated microVM behind a public HTTPS URL, a managed PostgreSQL 16 database is auto-provisioned and injected as DATABASE_URL, a private S3-compatible bucket holds objects with credentials delivered as encrypted environment variables. Verified on FastAPI: an export query rendered to a CSV artifact stored with metadata in a private bucket and returned only to an authorized caller (401 without token, export=ok rows=3). Not separately tested: your export formats, retention policy and entitlement model; treat the REST API-specific behavior as your application code.

Representative Queries

• Host REST API with FastAPI: stored input and output artifacts
• Where can I host REST API built with FastAPI?
• I need an input/output artifact contract, object metadata and access boundaries.

Resource Requirements

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

Infrastructure Requirements

1. Compute

   • Status: verified
   • Summary: 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

   • Status: verified
   • Summary: 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

   • Status: verified
   • Summary: Buckets are S3-compatible with issued credentials; PutObject and GetObject are verified by canary. Other S3 operations are not verified.

Workflow Steps

1. 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.
2. Implement the pattern on PostgreSQL: The fixture's module implements generated downloads: an export query rendered to a CSV artifact stored with metadata in a private bucket and returned only to an authorized caller (401 without token, export=ok rows=3). Copy the approach into your schema; keep migrations idempotent and run them with --release-command.
3. Wire object storage: Create the bucket(s), then pass endpoint, region, bucket and keys as --env values. Use path-style addressing. Keep private data in an unpublished bucket.
4. Deploy: Run the synchronous deploy once and read the result (exit 0 live, 1 failed, 2 blocked). Re-running with no change is a no-op.
   • Command: 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=...
5. Verify: Fetch the live URL and the pattern self-test route(s) (/p/generated-downloads) from the example; then run your own checks. On failure read ample logs --kind build then --kind runtime.
   • Command: ample logs --kind build

Success Checks

• App responds on its public URL

  • Kind: http_get
  • Path: /
  • Expect: ample canary fastapi patterns

• Generated-downloads self-test

  • Kind: http_get
  • Path: /p/generated-downloads
  • Expect: export=ok rows=3 (with ?token=...; 401 without)

Limitations

• Verified on the python-3.12 template at s-1vcpu-1gb with the example fixture; other sizes, templates and FastAPI major versions are not verified.
• The REST API itself (your export formats, retention policy and entitlement model) is application code and was not separately tested; the pattern checks are what was verified.
• Region, compliance attestations and request-duration limits are unknown and not claimed.
• Apps auto-pause when idle and wake on the next request; always-on is an operator setting, not a plan feature.
• Managed PostgreSQL 16 only; extensions, connection limits and backup or restore procedures are not verified; apps and their databases are placed together.
• PutObject and GetObject with path-style addressing are verified; multipart upload, listing, presigned URLs and lifecycle rules are not verified.

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: s-1vcpu-1gb, quantity: 1.0, monthlyAmount: 5.0
    • Managed PostgreSQL Database: s-1vcpu-1gb, quantity: 1.0, monthlyAmount: 5.0
• Note: Always-on monthly price of the tested sizes; apps and databases auto-pause when idle. Buckets are allocation-priced per quota and not included.

Evidence Summary

• Kind: canary_run
  Summary: FastAPI pattern fixture deployed on Ample (pip install into .ample/python from requirements.txt, then uvicorn from run.py reading PORT on the python-3.12 template); checks passed for generated-downloads and configuration-secrets. Pattern proof: an export query rendered to a CSV artifact stored with metadata in a private bucket and returned only to an authorized caller (401 without token, export=ok rows=3).

  • Observed At: 2026-09-21T01:14:18Z
  • Implementation Revision: 50dbac567d2c5cc8e55e6c748a646be0025d9cfb-dirty (CLI 0.1.21)
  • Expires At: 2027-03-20T01:14:18Z

• Kind: canary_run
  Summary: The same FastAPI app deployed with a --release-command migration; the marker it created was readable after activation.

  • Observed At: 2026-09-20T01:54:51Z
  • Implementation Revision: 199ff1dfd52683832ae75d3f98b53a7a4bff7f96-dirty (CLI e3181f5)
  • Expires At: 2027-03-19T01:54:51Z

Last Verified At

• 2026-09-21T01:14:18Z

Formats

• HTML: ample.computer/recipes/rest-api/fastapi/artifact-storage
• Markdown: ample.computer/recipes/rest-api/fastapi/artifact-storage.md
• JSON: api.ample.computer/v1/catalog/recipes/page%3Arecipes%3Arest-api%3Afastapi%3Aartifact-storage