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

Host ai chat application with Express: Postgres-backed state

Deploy a 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, a managed PostgreSQL 16 database is auto-provisioned and injected 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). Not separately tested: your job types, payload schema and retry policy; treat the ai chat application-specific behavior as your application code.

Representative Queries

• Host ai chat application with Express: Postgres-backed state
• Where can I host AI chat application built with Express?
• 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

Express

Workload

AI chat application

Release Status

Published

Support Status

Verified

Execution Status

Ready

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

Tested Configuration

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

Workflow 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: 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.
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.

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: Expect to receive ample canary express patterns.
• Durable-job-state self-test: Expect to receive job=done attempts=1 idempotent=true on path /p/durable-job-state.

Limitations

• Verified on the node-22 template at s-1vcpu-1gb with the example fixture; other sizes, templates and Express major versions are not verified.
• The ai chat application itself (your job types, payload schema and retry policy) is application code and was not separately tested; the pattern checks are what was verified.
• 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 databases are placed together.

Cost Estimate

• Currency: USD
• Monthly Amount: 10.0
• Components:
  • App server: s-1vcpu-1gb, quantity: 1.0, monthly amount: 5.0
  • Managed PostgreSQL database: s-1vcpu-1gb, quantity: 1.0, monthly amount: 5.0
• Note: Always-on monthly price of the tested sizes; apps and databases auto-pause when idle.

Evidence Summary

• Canary Run: Express pattern fixture deployed on Ample; checks passed for durable-job-state and configuration-secrets.
• Canary Run: The same Express app deployed with a --release-command migration; the marker it created was readable after activation.

Unknowns

• Region availability is unknown until a verified region fact is recorded.
• Compliance attestations are unknown; none are claimed.