Host ai chat application with Express: Postgres-backed state

Summary

Deploy an AI chat application built with Express on Ample using the durable job state pattern. Compute runs the app in an isolated microVM behind a public HTTPS URL, with a managed PostgreSQL 16 database auto-provisioned as DATABASE_URL. Verified on Express: 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).

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

• A Express project that builds and starts with the documented commands (npm install, npm run build --if-present, npm run start on the node-22 template)
• 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

Exact tested configuration

• Template: node-22
• Runtime: node
• Size: s-1vcpu-1gb
• Install: npm install
• Build: npm run build --if-present
• Start: npm run start

Steps

1. Build and start. npm install, npm run build --if-present, npm run start on the node-22 template. The server must bind 0.0.0.0 on PORT.

2. Implement the pattern on PostgreSQL. Implement durable job state: a jobs table with a state and attempts counter, processing inside a row-locked transaction. 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).

   ample deploy . --name <app-name> --public
   

4. Verify. Fetch the live URL and the pattern self-test route(s) (/p/durable-job-state) from the example; run your checks. On failure, read ample logs <deployment_id> --kind build then --kind runtime.

   ample logs <deployment_id> --kind build
   

Tested examples

• Express pattern fixture: Multi-pattern Express app whose durable job state module was checked live; the module is under tests/deploy-canaries/_pattern-modules.

Success checks

• App responds on its public URL (/ on the live URL).
• Durable job state self-test (/p/durable-job-state on the live URL).

Limitations

• Verified on the node-22 template; other sizes, templates, and Express major versions are not verified.
• The AI chat application behavior is not separately tested; the pattern checks are what was verified.
• Auto-pause and wake on requests; always-on is an operator setting, not a plan feature.

Cost estimate

Estimated 10.00 USD per month.

• App server x1 s-1vcpu-1gb: 5.00 USD
• Managed PostgreSQL database x1 s-1vcpu-1gb: 5.00 USD

Verification evidence

• Canary run on 2026-09-21: Express pattern fixture deployed on Ample; checks passed for durable-job-state and configuration-secrets.
• Canary run on 2026-09-20: Express app deployed with a --release-command migration.

Execution binding

MCP tool ample_deploy, schema hash 876465fce906da0c, binding state current, required scopes: servers:write, databases:read.