# Host form collection with ASP.NET Core: file attachments

Deploy a form collection built with ASP.NET Core on Ample using the browser file uploads 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, a private S3-compatible bucket holds objects with credentials delivered as encrypted environment variables. Verified on ASP.NET Core: content-type and size validation that rejects disallowed files, an object written to a private bucket and a row linking the record to the object key (reject=ok upload=ok linked=ok). Not separately tested: your upload UI, allowed types, size limits and virus scanning; treat the form collection-specific behavior as your application code.

## Representative Queries
- Host form collection with ASP.NET Core: file attachments
- Where can I host Form collection built with ASP.NET Core?
- I need a restricted upload flow, file validation and record-to-object linkage.

## Resource Requirements
- primitive:compute
- primitive:postgres
- primitive:s3-compatible-object-storage

## Infrastructure Requirements
- **Compute**: Apps run in isolated x86_64 Firecracker microVMs that auto-pause when idle and wake on request; sizes are the priced VM sizes.
- **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.
- **S3-compatible object storage**: Buckets are S3-compatible with issued credentials; PutObject and GetObject are verified by canary. Other S3 operations are not verified.

## Prerequisites
1. 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)
2. A PostgreSQL driver reading DATABASE_URL at runtime (auto-provisioned when omitted, or supplied with `--env`)
3. A bucket from `ample bucket create` with its credentials passed as encrypted S3_* environment variables
4. An Ample account token with `servers:write`, `databases:read`, `buckets:read`

## Workflow 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 browser file uploads: content-type and size validation that rejects disallowed files, an object written to a private bucket and a row linking the record to the object key (reject=ok upload=ok linked=ok). Copy the approach into your schema; keep migrations idempotent and run them with `--release-command`.

### Wire object storage
- Create the bucket(s), then pass endpoint, region, bucket and keys as `--env` values. Use path-style addressing. Keep private data in an unpublished bucket.

### 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.
- Command: `ample deploy . --name  --public --env S3_ENDPOINT=... --env S3_REGION=... --env S3_BUCKET=... --env S3_ACCESS_KEY_ID=... --env S3_SECRET_ACCESS_KEY=...`

### Verify
- Fetch the live URL and the pattern self-test route(s) (`/p/browser-file-uploads`) from the example; then run your own checks. On failure read `ample logs  --kind build` then `--kind runtime`.
- Command: `ample logs  --kind build`

## Cost Estimate
- **Currency**: USD
- **Monthly Amount**: 10.0
- **Components**:
  - App server: s-1vcpu-1gb - $5.00/month
  - Managed PostgreSQL database: s-1vcpu-1gb - $5.00/month

## 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 form collection itself (your upload UI, allowed types, size limits and virus scanning) is application code and was not separately tested; the pattern checks are what was verified...

## Examples
### ASP.NET Core pattern fixture
- A Multi-pattern ASP.NET Core app whose browser file uploads module was checked live; the module is under tests/deploy-canaries/_pattern-modules.
  - Source Ref: `tests/deploy-canaries/asp-net-core-patterns`