experimental: what if - interceptors

tf5muxserver/mux_server.go

@@ -55,6 +55,13 @@ type muxServer struct {
 
 	// Underlying servers for requests that should be handled by all servers
 	servers []tfprotov5.ProviderServer
+
+	// interceptors []tfprotov5.Interceptor
+	interceptors []Interceptor
+}
+
+type Interceptor struct {
+	BeforeListResource func(context.Context, *tfprotov5.ListResourceRequest) context.Context
 }
 
 // ProviderServer is a function compatible with tf6server.Serve.
@@ -426,3 +433,48 @@ func NewMuxServer(_ context.Context, servers ...func() tfprotov5.ProviderServer)
 
 	return &result, nil
 }
+
+type Option func(*muxServer)
+
+func Servers(servers ...func() tfprotov5.ProviderServer) Option {
+	return func(mux *muxServer) {
+		for _, server := range servers {
+			mux.servers = append(mux.servers, server())
+		}
+	}
+}
+
+func Interceptors(interceptors ...Interceptor) Option {
+	return func(mux *muxServer) {
+		mux.interceptors = append(mux.interceptors, interceptors...)
+	}
+}
+
+// NewMuxServerWithOptions returns a muxed server that will route gRPC requests between
+// tfprotov5.ProviderServers specified. The GetProviderSchema method of each
+// is called to verify that the overall muxed server is compatible by ensuring:
+//
+//   - All provider schemas exactly match
+//   - All provider meta schemas exactly match
+//   - Only one provider implements each managed resource
+//   - Only one provider implements each data source
+//   - Only one provider implements each function
+//   - Only one provider implements each ephemeral resource
+//   - Only one provider implements each list resource
+//   - Only one provider implements each resource identity
+func NewMuxServerWithOptions(_ context.Context, options ...Option) (*muxServer, error) {
+	result := muxServer{
+		dataSources:          make(map[string]tfprotov5.ProviderServer),
+		ephemeralResources:   make(map[string]tfprotov5.ProviderServer),
+		listResources:        make(map[string]tfprotov5.ProviderServer),
+		functions:            make(map[string]tfprotov5.ProviderServer),
+		resources:            make(map[string]tfprotov5.ProviderServer),
+		resourceCapabilities: make(map[string]*tfprotov5.ServerCapabilities),
+	}
+
+	for _, option := range options {
+		option(&result)
+	}
+
+	return &result, nil
+}

tf5muxserver/mux_server_ListResource.go

@@ -17,6 +17,13 @@ func (s *muxServer) ListResource(ctx context.Context, req *tfprotov5.ListResourc
 	ctx = logging.InitContext(ctx)
 	ctx = logging.RpcContext(ctx, rpc)
 
+	for _, i := range s.interceptors {
+		if i.BeforeListResource == nil {
+			continue
+		}
+		ctx = i.BeforeListResource(ctx, req)
+	}
+
 	server, diags, err := s.getListResourceServer(ctx, req.TypeName)
 
 	if err != nil {