response streaming.md

Host rest api with ASP.NET Core: streamed responses

Summary

Deploy a rest api built with ASP.NET Core on Ample using the streaming response service 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 ASP.NET Core: 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). Not separately tested: your event schema, reconnection strategy and any per-request duration ceiling beyond the 70 seconds measured; treat the rest api-specific behavior as your application code.

Infrastructure requirements

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

A ASP.NET Core project that builds and starts with the documented commands (dotnet publish -c Release -o out in the builder, then dotnet .dll on the dotnet-10 template with ASPNETCORE_URLS bound to PORT)
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

Exact tested configuration

template: dotnet-10
runtime: dotnet
size: s-1vcpu-1gb
build: dotnet publish -c Release -o out
start: ASPNETCORE_URLS=http://0.0.0.0:$PORT dotnet out/$(basename $(ls out/*.runtimeconfig.json | head -n 1) .runtimeconfig.json).dll

Steps

Build and start. dotnet publish -c Release -o out in the builder, then dotnet .dll on the dotnet-10 template with ASPNETCORE_URLS bound to PORT. 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> --public
```
Verify. 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 read ample logs <deployment_id> --kind build then --kind runtime.
```
ample logs <deployment_id> --kind build
```

Tested examples

ASP.NET Core pattern fixture (tests/deploy-canaries/asp-net-core-patterns): Multi-pattern ASP.NET Core app whose streaming response service module was checked live; the module is under tests/deploy-canaries/_pattern-modules.

Success checks

app responds on its public URL (/ on the live URL, expect ample canary asp net core patterns)
streaming-response-service self-test (/p/streaming-response-service on 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

Verified on the dotnet-10 template at s-1vcpu-1gb with the example fixture; other sizes, templates and ASP.NET Core major versions are not verified.
The rest 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 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.

Verification evidence

canary_run on 2026-09-21T01:15:54Z at revision 50dbac567d2c5cc8e55e6c748a646be0025d9cfb-dirty (CLI 0.1.21): ASP.NET Core pattern fixture deployed on Ample (dotnet publish -c Release -o out in the builder, then dotnet .dll on the dotnet-10 template with ASPNETCORE_URLS bound to PORT); 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 2027-03-20T01:15:54Z)
canary_run on 2026-09-20T23:34:47Z at revision 4d1511e574302f3904b75088bd4048a0975218b3-dirty (CLI 0.1.21): The same ASP.NET Core app deployed with a --release-command migration; the marker it created was readable after activation. (expires 2027-03-19T23:34:47Z)

Last verified: 2026-09-21T01:15:54Z