start implementing gw serve mux support

pkg/srv/grpc/gateway.go

@@ -0,0 +1,43 @@
+package grpc
+
+import (
+	"context"
+	"net/http"
+
+	"github.com/grpc-ecosystem/grpc-gateway/runtime"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/trace"
+	"google.golang.org/grpc"
+
+	"gitea.libretechconsulting.com/rmcguire/go-app/pkg/srv/grpc/opts"
+)
+
+const API_PATH = "/api" // TODO: Make Configurable
+
+// TODO: Add GetClientConn method to appGRPCServer that supports TLS, auth, etc..
+// Will probably have to convert server opts to client opts
+func (a *appGRPCServer) registerServiceGatewayHandlers(ctx context.Context, service *opts.GRPCService) {
+	if len(service.GwRegistrationFuncs) < 1 {
+		return
+	} else if a.gatewayMux == nil {
+		a.gatewayMux = runtime.NewServeMux()
+	}
+
+	ctx, span := a.tracer.Start(ctx, "appgrpc.init.prepare.service.gwHandlers", trace.WithAttributes(
+		attribute.String("service", service.Name),
+		attribute.Int("gwHandlers", len(service.GwRegistrationFuncs)),
+	))
+	defer span.End()
+
+	// TODO: move to GetClientConn method which doesn't exist yet
+	clientConn, _ := grpc.NewClient(a.opts.Listen)
+
+	for _, registerGW := range service.GwRegistrationFuncs {
+		registerGW(ctx, a.gatewayMux, clientConn)
+	}
+}
+
+// Add our gateway mux to an existing http.ServeMux
+func (a *appGRPCServer) mergeGatewayMuxWithHTTPMux(mux *http.ServeMux) {
+	mux.Handle(API_PATH, http.StripPrefix(API_PATH, a.gatewayMux))
+}