improve shutdown and app service boilerplate

pkg/service/service.go

@@ -0,0 +1,63 @@
+// Package service defines generics around implementation of
+// a new service that provides configuration for go-app
+//
+// The interface is meant to make the template more clear to implement
+// without unnecessary changes in main.go
+package service
+
+import (
+	"context"
+
+	"gitea.libretechconsulting.com/rmcguire/go-server-with-otel/pkg/config"
+
+	optsgrpc "gitea.libretechconsulting.com/rmcguire/go-app/pkg/srv/grpc/opts"
+	optshttp "gitea.libretechconsulting.com/rmcguire/go-app/pkg/srv/http/opts"
+)
+
+type ShutdownFunc func(ctx context.Context) (string, error)
+
+type AppService interface {
+	Init(ctx context.Context, config *config.ServiceConfig) (ShutdownFunc, error)
+	GetGRPC() *optsgrpc.AppGRPC
+	GetHTTP() *optshttp.AppHTTP
+}
+
+// MergeServices is used if multiple services are served by this server
+// with their own distinct packages and configuration
+//
+// You should be overriding the done chan, listener, or any other
+// configuration used by the SERVER rather than the individual services.
+func MergeServices(ctx context.Context, appServices ...AppService) (*optsgrpc.AppGRPC, *optshttp.AppHTTP) {
+	mergedGRPC := &optsgrpc.AppGRPC{}
+	for _, svc := range appServices {
+		mergedGRPC = mergeGRPC(mergedGRPC, svc.GetGRPC())
+	}
+
+	mergedHTTP := &optshttp.AppHTTP{}
+	for _, svc := range appServices {
+		mergedHTTP = mergeHTTP(mergedHTTP, svc.GetHTTP())
+	}
+	mergedHTTP.Ctx = ctx
+
+	return mergedGRPC, mergedHTTP
+}
+
+func mergeHTTP(a *optshttp.AppHTTP, b *optshttp.AppHTTP) *optshttp.AppHTTP {
+	return &optshttp.AppHTTP{
+		Funcs:        append(a.Funcs, b.Funcs...),
+		Middleware:   append(a.Middleware, b.Middleware...),
+		Handlers:     append(a.Handlers, b.Handlers...),
+		HealthChecks: append(a.HealthChecks, b.HealthChecks...),
+	}
+}
+
+func mergeGRPC(a *optsgrpc.AppGRPC, b *optsgrpc.AppGRPC) *optsgrpc.AppGRPC {
+	return &optsgrpc.AppGRPC{
+		Services:           append(a.Services, b.Services...),
+		GRPCOpts:           append(a.GRPCOpts, b.GRPCOpts...),
+		UnaryInterceptors:  append(a.UnaryInterceptors, b.UnaryInterceptors...),
+		StreamInterceptors: append(a.StreamInterceptors, b.StreamInterceptors...),
+		GRPCDialOpts:       append(a.GRPCDialOpts, b.GRPCDialOpts...),
+		GRPCGatewayOpts:    append(a.GRPCGatewayOpts, b.GRPCGatewayOpts...),
+	}
+}