Private-only service causes gateway to panic

[marcwickenden]

When self-hosting I build two docker images. One with --gateways= to not include the api-gateway. The second with --gateways=api-gateway to include this.

Among my services there is one called email which contains a single private func SendMail used by various Encore services. It should not, as the name suggests, be used publicly and therefore does not need to be in the gateway.

When the gateway starts it errored like this:

panic: service "email" not found in service discovery when hosted in gateway

goroutine 1 [running]:
encore.dev/appruntime/apisdk/api.(*Server).createGatewayHandlerAdapter(0xc0006c5dc0, {0x309fdf8, 0x4889040})
        /home/runner/.encore/runtimes/go/appruntime/apisdk/api/gateway.go:29 +0x774
encore.dev/appruntime/apisdk/api.(*Server).registerEndpoint(0xc0006c5dc0, {0x309fdf8, 0x4889040}, {0x24b7aa0, 0x2d55a38})
        /home/runner/.encore/runtimes/go/appruntime/apisdk/api/server.go:334 +0x1c5
encore.dev/appruntime/apisdk/api.RegisterEndpoint(...)
        /home/runner/.encore/runtimes/go/appruntime/apisdk/api/registry.go:8
encore.app/email.init.0()
        /home/runner/work/hub/hub/backend/email/encore_internal__api.go:14 +0x36

This appeared to relate to service discovery definitions being built for gateway including private services too.

[marcwickenden]

It turns out that specifying --gateways= doesn't do what I thought it did but also I've now got this working without this fix which suggests other things were at play. The change I made was not to the gateway though, it was to the other image without the gateway where I had to specify all the services with --services=x,y,x which it turns out will mean the gateway isn't included. So in summary, I'm not actually sure if this is a bug or not even though this fix definitely prevented the issue I was seeing.

[marcwickenden]

Ok, I've confirmed this is definitely a bug but only occurs when there is a service which only has a private endpoint in it. I've worked around this by adding a NoOp func to my affected services:

//encore:api auth
func (s *Service) NoOp(ctx context.Context) error {
	// This is literally here just so there's one other endpoint
	// in the service to make sure it gets correctly added to containers
	return nil
}