Host rest api with FastAPI: Postgres-backed state

Summary

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.

Infrastructure requirements

• 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.)
• 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.)

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

Exact 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

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.

   ample deploy . --name <app-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.

   ample logs <deployment_id> --kind build
   

Tested examples

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

Success checks

• root route responds (/ on the live URL, expect ample canary fastapi postgres api)
• database insert and count succeed (/items on the live URL, expect postgres=ok)

Limitations

• Verified on the node-22 template at s-1vcpu-1gb; other templates and sizes are not verified by this recipe.
• 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 managed databases are placed together; cross-node shared databases are unsupported.

Cost estimate

Estimated 10.00 USD per month (size prices from pricing.toml at build revision a1b8c38919e59cd035ebabaced73cf84ece24371).

• app server x1 s-1vcpu-1gb: 5.00 USD
• managed PostgreSQL database x1 s-1vcpu-1gb: 5.00 USD

Apps and managed databases auto-pause when idle; the estimate is the always-on monthly price of the tested sizes. Plan quotas and budgets apply.

Verification evidence

• canary_run on 2026-09-20T01:42:25Z at revision 199ff1dfd52683832ae75d3f98b53a7a4bff7f96-dirty (CLI e3181f5): 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. (expires 2027-03-19T01:42:25Z)
• canary_run on 2026-09-19T23:55:33Z at revision 1764076-tls-account-903d345: Node app needing PostgreSQL with no DATABASE_URL: a managed database was auto-provisioned and /db reported postgres=ok. (expires 2027-03-18T23:55:33Z)

Last verified: 2026-09-20T01:42:25Z

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 current, required scopes: servers:write, databases:read.