page:recipes:mobile backend:express:persistent state

Host mobile backend with Express: Postgres-backed state

Deploy a mobile backend 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 mobile backend-specific behavior as your application code.

Representative Queries

• Host mobile backend with Express: Postgres-backed state
• Where can I host Mobile backend built with Express?
• I need a durable state schema and retry/recovery semantics implemented by application code.

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

Resource Requirements

• primitive:compute
• primitive:postgres

Infrastructure Requirements

1. Compute: 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: Managed PostgreSQL 16 runs in its own microVM and is auto-provisioned when an app needs a database and no DATABASE_URL is supplied.

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

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 mobile backend 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.

Cost Estimate

• Currency: USD
• Monthly Amount: 10.0
• 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

Success Checks

1. App responds on its public URL: Verify by checking / expects to receive ample canary express patterns.
2. Durable-job-state self-test: Verify by checking /p/durable-job-state expects to receive job=done attempts=1 idempotent=true.

Next Actions

1. Browse the catalog index: GET /v1/catalog
2. Search published recipes by intent, stack and constraints: POST /v1/catalog/search
3. Prepare a side-effect-free deployment plan for an authorized project: POST /v1/catalog/plan
4. Read the existing agent authentication setup: GET /mcp/setup