Host rest api with FastAPI: Postgres-backed state

Deploy a FastAPI REST API whose durable state lives in a managed PostgreSQL 16 database. With no DATABASE_URL supplied, Ample provisions the database and injects the connection string as an encrypted environment variable; the API stores rows with psycopg and serves them from a public HTTPS URL.

Representative Queries

• Host rest api with FastAPI: Postgres-backed state
• Where can I host REST API built with FastAPI?
• I need a durable state schema and retry/recovery semantics implemented by application code.

Resource Requirements

• primitive:compute
• primitive:postgres

Infrastructure Requirements

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

Framework

FastAPI

Workload

REST API

Release Status

published

Support Status

verified

Execution Status

ready

Prerequisites

• requirements.txt with the framework, a server and psycopg
• A run.py that starts the server on PORT and 0.0.0.0 (pass --start "python3 run.py")
• Tables created by the app or by a --release-command migration, not assumed to exist
• An Ample account token with servers:write and databases:read

Tested Configuration

• Template: python-3.12
• Runtime: python
• Size: s-1vcpu-1gb
• Install: python3 -m pip install --target .ample/python -r requirements.txt
• Start: PYTHONPATH=.ample/python:${PYTHONPATH:-} python3 run.py

Input Schema

• name: App name (lowercase, digits and dashes)
• path: Project directory to deploy, or one service name from ample.toml
• start: Start command override when detection cannot infer it (Python apps pass one explicitly)

Workflow Steps

1. Read DATABASE_URL at runtime: Open the connection from the environment inside request handlers or a pool; a local .env is replaced by the managed database in production.
2. Deploy: Run the existing synchronous deploy once from the project directory and read the result. Exit 0 is live, 1 is failed, 2 is blocked on a required preflight action. Re-running with no change is a content-addressed no-op.
   • Command: ample deploy . --name --public --format json --start "python3 run.py"
3. 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.
   • Command: ample logs --kind build

Examples

• FastAPI + PostgreSQL canary: REST API with an items table in an auto-provisioned managed PostgreSQL database. Source Reference: tests/deploy-canaries/fastapi-postgres-api

Success Checks

• Root route responds: expected response is "ample canary fastapi postgres api" accessed via path: /.
• Database insert and count succeed: expected response is "postgres=ok" accessed via path: /items.

Limitations

• Verified on the node-22 template at s-1vcpu-1gb; other templates and sizes are not verified by this recipe.
• Managed PostgreSQL 16 only; extensions, connection limits and backup or restore procedures are not verified.

Cost Estimate

• Monthly Amount: 10.0 USD
• Breakdown:
  • App server: s-1vcpu-1gb - 5.0 USD
  • Managed PostgreSQL database: s-1vcpu-1gb - 5.0 USD

Evidence Summary

• Summary: FastAPI REST API using psycopg with no DATABASE_URL supplied: Ample auto-provisioned a managed PostgreSQL 16 database and /items reported postgres=ok after a real insert and count.
  • Observed At: 2026-09-20T01:42:25Z

Last Verified At

2026-09-20T01:42:25Z