Connect Postgres for Flask

Summary

Connect a Flask app to PostgreSQL on Ample. Read DATABASE_URL at runtime with psycopg: when you supply one with --env it is delivered encrypted and takes precedence; when you supply none and the app needs PostgreSQL, Ample auto-provisions a managed PostgreSQL 16 database and injects its connection string.

Infrastructure requirements

• psycopg reading the DATABASE_URL environment variable at runtime
• Either a production DATABASE_URL to pass with --env, or nothing (auto-provision)
• 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 app.py

Steps

1. Read the URL at runtime. Open connections from the DATABASE_URL environment variable inside the app; never commit credentials and never connect at build time.

2. Choose the source of the database. Pass --env DATABASE_URL=... for an existing database, or omit it to let Ample provision a managed one on first deploy and reuse it on redeploys.

   ample deploy . --name <app-name> --public --start "python3 run.py"
   

3. Test the connection through the app. Expose a route (/items) that runs a trivial query and returns postgres=ok.

4. 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

• Flask + PostgreSQL canary (tests/deploy-canaries/flask-postgres-app): Auto-provisioned managed database with a real query.

Success checks

• database route reports a live connection (/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

Verification evidence

• canary_run on 2026-09-20T01:42:25Z at revision 199ff1dfd52683832ae75d3f98b53a7a4bff7f96-dirty (CLI e3181f5): Flask app (waitress) using psycopg with an auto-provisioned managed PostgreSQL database: /items reported postgres=ok and /config confirmed the encrypted secret. (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.