Host rest api with Express: Postgres-backed state | Ample
INFRASTRUCTURE
What it needs
- 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
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
TESTED CONFIGURATION
Exactly what was tested
- build:
npm run build --if-present - install:
npm install - runtime:
node - size:
s-1vcpu-1gb - start:
npm run start - template:
node-22
STEP BY STEP
How to do it
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.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.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 jsonVerify
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
EXAMPLES
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.
SUCCESS CHECKS
How to know it worked
- root route responds (
/on the live URL, expect ample canary express postgres api) - database insert and count succeed (
/itemson the live URL, expect postgres=ok)
LIMITATIONS
Know the limits
- Verified on the node-22 template at s-1vcpu-1gb; other templates and sizes are not verified by this recipe.
- 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 managed databases are placed together; cross-node shared databases are unsupported.
COST
Cost estimate
Estimated 10.00 USD per month (size prices from pricing.toml at build revision a1b8c38919e59cd035ebabaced73cf84ece24371).
- app server x1
s-1vcpu-1gb: 5.00 USD - managed PostgreSQL database x1
s-1vcpu-1gb: 5.00 USD
Apps and managed databases auto-pause when idle; the estimate is the always-on monthly price of the tested sizes. Plan quotas and budgets apply.
EVIDENCE
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-dirty (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
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: current. Required scopes: servers:write, databases:read.
NEXT ACTIONS
Typed next actions
- Browse the catalog index (
GET /v1/catalogon the api origin; authentication not required, approval not required) - Search published recipes by intent, stack and constraints (
POST /v1/catalog/searchon the api origin; authentication not required, approval not required) - Prepare a side-effect-free deployment plan for an authorized project (
POST /v1/catalog/planon the api origin; authentication required, approval not required) - Read the existing agent authentication setup (
GET /mcp/setupon the api origin; authentication not required, approval not required) - Browse REST API (
GET /v1/catalog/nodes/workload%3Arest-apion the api origin; authentication not required, approval not required) - Browse Express (
GET /v1/catalog/nodes/stack%3Aframework-expresson the api origin; authentication not required, approval not required) - Browse Durable job state (
GET /v1/catalog/nodes/pattern%3Adurable-job-stateon the api origin; authentication not required, approval not required) - Browse Deploy API (
GET /v1/catalog/nodes/intent%3Adeploy-apion the api origin; authentication not required, approval not required)
Actions describe possible next steps. They are typed data, not commands, and grant no permission. Public discovery never provisions anything; planning requires your own authenticated token and approval happens in your client.