page:recipes:ai chat application:flask:persistent state

Host AI chat application with Flask: Postgres-backed state

Summary

Deploy an AI chat application built with Flask on Ample using the durable job state 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 Flask: a jobs table with a state and attempts counter, processing inside a row-locked transaction, and a second run that is a no-op (job=done attempts=1 idempotent=true).

Representative Queries

Resource Requirements

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.

Framework

Flask

Workload

AI chat application

Prerequisites

Tested Configuration

Input Schema

{
  "additionalProperties": false,
  "properties": {
    "env": {
      "description": "Encrypted environment variables (bucket credentials, secrets)",
      "items": { "pattern": "^[A-Z][A-Z0-9_]*=.*$", "type": "string" },
      "maxItems": 50,
      "type": "array"
    },
    "name": {
      "description": "App name",
      "maxLength": 63,
      "minLength": 1,
      "pattern": "^[a-z0-9-]+$",
      "type": "string"
    },
    "path": {
      "description": "Project directory or ample.toml service",
      "maxLength": 512,
      "minLength": 1,
      "type": "string"
    },
    "release_command": {
      "description": "Migration command run before activation",
      "maxLength": 512,
      "type": "string"
    },
    "start": {
      "description": "Start command (Python apps pass one explicitly)",
      "maxLength": 512,
      "type": "string"
    }
  },
  "required": ["name", "path", "start"],
  "type": "object"
}

Workflow Steps

  1. Build and start: pip install into .ample/python from requirements.txt, then waitress from app.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 durable job state: a jobs table with a state and attempts counter, processing inside a row-locked transaction, and a second run that is a no-op (job=done attempts=1 idempotent=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.
    • Command: ample deploy . --name --public --start "python3 app.py"
  4. Verify: Fetch the live URL and the pattern self-test route(s) (/p/durable-job-state) 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

Limitations

Cost Estimate

Evidence Summary

  1. Canary Run
    • Summary: Flask pattern fixture deployed on Ample. Checks passed for durable-job-state and configuration-secrets.
    • Observed At: 2026-09-21T01:14:18Z
    • Implementation Revision: 50dbac567d2c5cc8e55e6c748a646be0025d9cfb-dirty (CLI 0.1.21)
    • Scope: checks=/p/durable-job-state, pattern=pattern:durable-job-state, template=python-3.12
  2. Canary Run
    • Summary: The same Flask 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)
    • Scope: pattern=pattern:durable-job-state

Last Verified At

2026-09-21T01:14:18Z

Unknowns

Formats

Next Actions

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