page:recipes:ai workflow runner:fastify:persistent state

Host ai workflow runner with Fastify: Postgres-backed state

Summary

Deploy an AI workflow runner built with Fastify 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 Fastify: 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 workflow runner-specific behavior as your application code.

Resource Requirements

• Primitive: Compute
• Primitive: Postgres

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.

Prerequisites

• A Fastify 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

Workflow Steps

1. Build and start

   • Command: 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

   • Command: ample deploy . --name --public

4. Verify

   • Command: ample logs --kind build

Limitations

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

Success Checks

1. App responds on its public URL

   • Path: /
   • Expected: ample canary fastify patterns

2. Durable-job-state self-test

   • Path: /p/durable-job-state
   • Expected: job=done attempts=1 idempotent=true

Examples

• Fastify pattern fixture
  • Description: Multi-pattern Fastify app whose durable job state module was checked live; the module is under tests/deploy-canaries/_pattern-modules.
  • Source Ref: tests/deploy-canaries/fastify-patterns.

Cost Estimate

• Currency: USD
• Monthly Amount: 10.0
• Basis: Size prices from pricing.toml (loaded by the API)

Components:

• App server: size: s-1vcpu-1gb, quantity: 1.0, monthly amount: 5.0
• Managed PostgreSQL database: size: 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.