page:recipes:approval workflow:fastapi:relational workspace

Host approval workflow with FastAPI: relational workspace data

Summary

Deploy an approval workflow built with FastAPI on Ample using the relational records pattern. Compute runs the app in an isolated microVM behind a public HTTPS URL, and a managed PostgreSQL 16 database is auto-provisioned and injected as DATABASE_URL.

• Verified on FastAPI: a workspace-scoped table, an explicit state machine (draft to review to published) that rejects invalid transitions, and a cross-workspace read that returns nothing (transitions=true isolation=true).
• Not separately tested: your record schema, states and access rules; treat the approval workflow-specific behavior as your application code.

Representative Queries

• Host approval workflow with FastAPI: relational workspace data
• Where can I host Approval workflow built with FastAPI?
• I need a workspace-specific schema, state transitions and access rules.

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 relational records: a workspace-scoped table, an explicit state machine (draft to review to published) that rejects invalid transitions, and a cross-workspace read that returns nothing (transitions=true isolation=true). Copy the approach into your schema; keep migrations idempotent and run them with --release-command.
3. 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.
   ample deploy . --name --public --start "python3 run.py"
4. Verify
   Fetch the live URL and the pattern self-test route(s) (/p/relational-records) from the example; then run your own checks. On failure read ample logs --kind build then --kind runtime.
   ample logs --kind build

Prerequisites

• A FastAPI project that builds and starts with the documented commands.
• A PostgreSQL driver reading DATABASE_URL at runtime (auto-provisioned when omitted, or supplied with --env).
• An Ample account token with servers:write, databases:read.

Success Checks

• app responds on its public URL
• relational-records self-test
  • Kind: http_get
  • Path: /p/relational-records
  • Expect: records=ok transitions=true isolation=true

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 approval workflow itself 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.

Cost Estimate

• Monthly Amount: $10.00
• Currency: USD
• Components:
  • App server: s-1vcpu-1gb
  • Managed PostgreSQL database: s-1vcpu-1gb