## The short version

Deploy an Express REST API whose durable state lives in a managed PostgreSQL 16 database. With no DATABASE_URL supplied, Ample provisions the database and injects the connection string as an encrypted environment variable; the API stores rows with pg and serves them from a public HTTPS URL.

## What it needs

- [Compute](/content/discover/primitive/compute/index.html): verified (Apps run in isolated x86_64 Firecracker microVMs; sizes are the priced VM sizes.)
- [Postgres](/content/discover/primitive/postgres/index.html): 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.)

## Before you start

- A package.json with a start script that listens on process.env.PORT (default 3000) and 0.0.0.0
- The pg driver (or another PostgreSQL client) reading process.env.DATABASE_URL
- Tables created by the app or by a --release-command migration, not assumed to exist
- An Ample account token with servers:write and databases:read

## How to do it

1. **Check the start script**  
   Ample runs npm install, npm run build --if-present and npm run start on the node-22 template. The server must bind 0.0.0.0 and read PORT.

2. **Read DATABASE_URL at runtime**  
   Create a pg Pool from process.env.DATABASE_URL. Do not hard-code localhost credentials; a local .env is replaced by the managed database in production.

3. **Deploy**  
   Run the existing synchronous deploy once from the project directory and read the result. Exit 0 is live, 1 is failed, 2 is blocked on a required preflight action. Re-running with no change is a content-addressed no-op.
   
   ```
   ample deploy . --name <app-name> --public --format json
   ```

4. **Verify**  
   Fetch the live URL and run the success checks below. On failure read the build log, then the runtime log, fix the cause and deploy again; do not blind-retry.
   
   ```
   ample logs <deployment_id> --kind build
   ```

## Tested examples

- **Express + pg canary** (`tests/deploy-canaries/express-postgres-api`): Express API with POST /items and GET /items backed by an auto-provisioned managed PostgreSQL database.

## How to know it worked

- root route responds (`/` on the live URL, expect ample canary express postgres api)
- database insert and count succeed (`/items` on the live URL, expect postgres=ok)

## Cost estimate

Estimated 10.00 USD per month (size prices from pricing.toml at build revision ca0b484a7a9957c573a88d3a32dc603c3c10135a).

- app server x1 `s-1vcpu-1gb`: 5.00 USD
- managed PostgreSQL database x1 `s-1vcpu-1gb`: 5.00 USD

Upper-bound monthly price of the tested sizes. Plan quotas and budgets apply.

## Verification evidence

- canary_run on 2026-09-19T23:55:33Z at revision `1764076-tls-account-903d345`: Express REST API using pg with no DATABASE_URL supplied: Ample auto-provisioned a managed PostgreSQL 16 database, injected the connection string, and /items reported postgres=ok after a real insert and count. (expires 2027-03-18T23:55:33Z)
- canary_run on 2026-09-19T23:55:33Z at revision `1764076-tls-account-903d345`: Node app needing PostgreSQL with no DATABASE_URL: a managed database was auto-provisioned and /db reported postgres=ok. (expires 2027-03-18T23:55:33Z)
- canary_run on 2026-09-19T23:55:33Z at revision `1764076-tls-account-903d345`: Express app with npm install and npm run start deployed on the node-22 template; the public URL served the expected response. (expires 2027-03-18T23:55:33Z)
- live_deployment on 2026-09-20T00:48:10Z at revision `199ff1dfd52683832ae75d3f98b53a7a4bff7f96 (CLI e3181f5)`: Authorized end-to-end run through the catalog: public search, verified contract, side-effect-free plan (ready_for_approval with a signed plan token), operator approval, handoff to ample_deploy, live URL, and the recipe's success checks passed. (expires 2027-03-19T00:48:10Z)

## Execution binding

MCP tool `ample_deploy` (registry `mcp:ample_deploy`), schema hash `876465fce906da0c` observed 2026-09-20T01:55:48.667900+00:00 at revision `199ff1dfd526`. Binding state at export: schema_changed. Required scopes: servers:write, databases:read.

## Typed next actions

- Browse the catalog index (`GET /v1/catalog` on the api origin; authentication not required, approval not required)
- Search published recipes by intent, stack and constraints (`POST /v1/catalog/search` on the api origin; authentication not required, approval not required)
- Prepare a side-effect-free deployment plan for an authorized project (`POST /v1/catalog/plan` on the api origin; authentication required, approval not required)
- Read the existing agent authentication setup (`GET /mcp/setup` on the api origin; authentication not required, approval not required)
- Browse REST API (`GET /v1/catalog/nodes/workload%3Arest-api` on the api origin; authentication not required, approval not required)
- Browse Express (`GET /v1/catalog/nodes/stack%3Aframework-express` on the api origin; authentication not required, approval not required)
- Browse Durable job state (`GET /v1/catalog/nodes/pattern%3Adurable-job-state` on the api origin; authentication not required, approval not required)
- Browse Deploy API (`GET /v1/catalog/nodes/intent%3Adeploy-api` on the api origin; authentication not required, approval not required)

## Identifiers and status

Recipe `page:recipes:rest-api:express:persistent-state`. Revision r1.

release **published** support **verified** execution **blocked (schema_changed: live tool schema differs from the recorded binding)**

Formats: [HTML](/content/recipes/rest-api/express/persistent-state/index.html) | [Markdown](/content/recipes/rest-api/express/persistent-state.md) | [JSON contract](https://api.ample.computer/v1/catalog/recipes/page%3Arecipes%3Arest-api%3Aexpress%3Apersistent-state)