[Bug]: An invalid vhost on a platform-api deployment returns 500 instead of a validation error #4166

Please select the area the issue is related to

Platform API

Please select the aspect the issue is related to

Aspect/API (API backends, definitions, contracts, interfaces, OpenAPI)

Description

Deploying a REST API through platform-api with an invalid metadata.vhostMain or metadata.vhostSandbox returns 500 INTERNAL_ERROR ("An unexpected error occurred."). It should return a 400 that names the invalid vhost. The value is a caller mistake, but the caller is told the server failed and is given no hint about what to fix.

Observed (POST /api/v0.9/rest-apis/{id}/deployments with base: current and a gatewayId)

• metadata.vhostMain: "bad_host": 500 {"code":"INTERNAL_ERROR","message":"An unexpected error occurred."}
• metadata.vhostMain: "-api.example.com" (leading hyphen): the same 500.
• metadata.vhostMain with a 64-character label: the same 500.
• metadata.vhostSandbox: "bad_host": the same 500.
• metadata.vhostMain: "_gateway_default_": 201, as expected.

Expected
A 400 with a validation error code and a message that says which vhost is invalid and why, as other deployment validation errors do (for example REST_API_DEPLOYMENT_VALIDATION_FAILED).

Cause
platform-api/internal/service/deployment.go:331-357 rejects the value with a plain fmt.Errorf("invalid vhostMain in metadata: %s", …) (and the same for vhostSandbox, and for a non-string value). That is not a catalog error, so serviceError (platform-api/internal/handler/service_error.go:41-46) maps it to apperror.Internal. Using apperror.RESTAPIDeploymentValidationFailed.New(...) there, as deployment.go:188-191 already does for base, would return a 400.

Steps to Reproduce

1. Create a REST API in platform-api and attach a connected gateway to it (POST /api/v0.9/rest-apis/{id}/gateways).
2. Send POST /api/v0.9/rest-apis/{id}/deployments with {"name": "d1", "base": "current", "gatewayId": "<gateway id>", "metadata": {"vhostMain": "bad_host"}}.
3. The response is 500 INTERNAL_ERROR.

Severity Level of the Issue

Severity/Minor (Non-critical functionality. Can be fixed in future releases)

Environment Details (with versions)

Current main (e90cde4). Platform-api and gateway built from source and run by the IT suite (tests/framework), on macOS with Rancher Desktop.