replace API server with transparent gRPC proxy that routes requests to local machine API

internal/machine/api/proxy/director.go

@@ -0,0 +1,37 @@
+package proxy
+
+import (
+	"context"
+	"github.com/siderolabs/grpc-proxy/proxy"
+	"sync"
+)
+
+// Director manages routing of gRPC requests between local and remote backends.
+type Director struct {
+	localTarget    string
+	localBackend   proxy.Backend
+	remoteBackends sync.Map
+
+	mu sync.RWMutex
+}
+
+func NewDirector(localSockPath string) *Director {
+	return &Director{
+		localBackend: NewLocalBackend(localSockPath),
+	}
+}
+
+// UpdateLocalAddress updates the local machine address used to identify which requests should be proxied
+// to the local gRPC server.
+func (d *Director) UpdateLocalAddress(target string) {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+
+	d.localTarget = target
+}
+
+// Director implements proxy.StreamDirector for grpc-proxy, routing requests to local or remote backends based
+// on gRPC metadata in the context.
+func (d *Director) Director(ctx context.Context, fullMethodName string) (proxy.Mode, []proxy.Backend, error) {
+	return proxy.One2One, []proxy.Backend{d.localBackend}, nil
+}