add grpc support

pkg/srv/grpc/grpc.go

@@ -16,18 +16,22 @@ import (
 )
 
 type appGRPCServer struct {
-	ctx        context.Context
-	tracer     trace.Tracer
-	meter      metric.Meter
-	opts       *opts.GRPCOpts
-	serverOpts []grpc.ServerOption
-	logger     *zerolog.Logger
-	server     *grpc.Server
+	ctx          context.Context
+	tracer       trace.Tracer
+	meter        metric.Meter
+	opts         *opts.GRPCOpts
+	serverOpts   []grpc.ServerOption
+	logger       *zerolog.Logger
+	server       *grpc.Server
+	shutdownFunc func(context.Context) error
+	doneChan     chan error
 }
 
-// TODO: This probably needs to pass back an error chan and a shutdown
-// func like the http server does
-func InitGRPCServer(ctx context.Context, opts *opts.GRPCOpts) error {
+// Returns a shutdown func, a channel indicating done / error,
+// and an up-front error if server fails to start
+func InitGRPCServer(ctx context.Context, opts *opts.GRPCOpts) (
+	func(context.Context) error, <-chan error, error,
+) {
 	appGRPC := &appGRPCServer{
 		ctx:        ctx,
 		tracer:     appotel.GetTracer(ctx, "grpc"),
@@ -35,6 +39,7 @@ func InitGRPCServer(ctx context.Context, opts *opts.GRPCOpts) error {
 		opts:       opts,
 		serverOpts: make([]grpc.ServerOption, 0),
 		logger:     zerolog.Ctx(ctx),
+		doneChan:   make(chan error),
 	}
 
 	ctx, span := appGRPC.tracer.Start(ctx, "appgrpc.init")
@@ -44,23 +49,21 @@ func InitGRPCServer(ctx context.Context, opts *opts.GRPCOpts) error {
 	if err := appGRPC.prepGRPCServer(ctx); err != nil {
 		span.RecordError(err)
 		span.SetStatus(codes.Error, "failed to prepare GRPC Server")
-		return err
+		return nil, nil, err
 	}
 
 	// Load span with server info
 	span.SetAttributes(appGRPC.getServerAttributes()...)
 
-	// Run, returning a shutdown func and an error chan
-	// TODO: Implement shutdown func and error chan
 	err := appGRPC.runGRPCServer(ctx)
 	if err != nil {
 		span.RecordError(err)
 		span.SetStatus(codes.Error, "failed to start GRPC Server")
-		return err
+		return nil, nil, err
 	}
 
 	span.SetStatus(codes.Ok, "")
-	return nil
+	return appGRPC.shutdownFunc, appGRPC.doneChan, nil
 }
 
 // Convert grpc.ServiceInfo map to []attribute.KeyValue