Host graphql api with Express: streamed responses | 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 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
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
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.Implement the pattern on PostgreSQL
The fixture's module implements streaming response service: a Server-Sent Events endpoint read incrementally through the public HTTPS gateway: five one-second chunks arrived spread over time with the first within seconds (not buffered), a 70-second stream of 36 chunks completed past common 60-second idle timeouts, and a client that disconnected after two chunks was observed and recorded by the server (disconnected=true). Copy the approach into your schema; keep migrations idempotent and run them with --release-command.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.ample deploy . --name <app-name> --publicVerify
Fetch the live URL and the pattern self-test route(s) (/p/streaming-response-service) from the example; then run your own checks. On failure readample logs <deployment_id> --kind buildthen--kind runtime.ample logs <deployment_id> --kind build
EXAMPLES
Tested examples
- Express pattern fixture (
tests/deploy-canaries/express-patterns): Multi-pattern Express app whose streaming response service module was checked live; the module is under tests/deploy-canaries/_pattern-modules.
SUCCESS CHECKS
How to know it worked
- app responds on its public URL (
/on the live URL, expect ample canary express patterns) - streaming-response-service self-test (
/p/streaming-response-serviceon the live URL, expect an SSE stream: data: id=, then chunk events one interval apart (read incrementally: first chunk within seconds, chunks spread over the interval), then data: done; /status?id= reports sent=N disconnected=true|false done=true|false)
LIMITATIONS
Know the limits
- 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 graphql api itself (your event schema, reconnection strategy and any per-request duration ceiling beyond the 70 seconds measured) 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
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
Always-on monthly price of the tested sizes; apps and databases auto-pause when idle. Buckets are allocation-priced per quota and not included.
EVIDENCE
Verification evidence
- canary_run on 2026-09-21T02:34:39Z at revision
1d28ae0-dirty (CLI 0.1.21): Express pattern fixture deployed on Ample (npm install, npm run build --if-present, npm run start on the node-22 template); checks passed for streaming-response-service and configuration-secrets. Pattern proof: a Server-Sent Events endpoint read incrementally through the public HTTPS gateway: five one-second chunks arrived spread over time with the first within seconds (not buffered), a 70-second stream of 36 chunks completed past common 60-second idle timeouts, and a client that disconnected after two chunks was observed and recorded by the server (disconnected=true). (expires 2027-03-20T02:34:39Z) - canary_run on 2026-09-20T01:54:51Z at revision
199ff1dfd52683832ae75d3f98b53a7a4bff7f96-dirty (CLI e3181f5): The same Express app deployed with a --release-command migration; the marker it created was readable after activation. (expires 2027-03-19T01:54:51Z)
EXECUTION
Execution binding
MCP tool ample_deploy (registry mcp:ample_deploy), schema hash 876465fce906da0c observed 2026-09-21T03:19:59.461917+00:00 at revision 49962bcade4f. 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 GraphQL API (
GET /v1/catalog/nodes/workload%3Agraphql-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 Streaming response service (
GET /v1/catalog/nodes/pattern%3Astreaming-response-serviceon 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.