Add minimal control plane with REST API, database, and reconciler

- REST API (chi router): sandbox CRUD, exec, pause/resume, file write/read
- PostgreSQL persistence via pgx/v5 + sqlc (sandboxes table with goose migration)
- Connect RPC client to host agent for all VM operations
- Reconciler syncs host agent state with DB every 30s (detects TTL-reaped sandboxes)
- OpenAPI 3.1 spec served at /openapi.yaml, Swagger UI at /docs
- Added WriteFile/ReadFile RPCs to hostagent proto and implementations
- File upload via multipart form, download via JSON body POST
- sandbox_id propagated from control plane to host agent on create

cmd/control-plane/main.go

@@ -0,0 +1,88 @@
+package main
+
+import (
+	"context"
+	"log/slog"
+	"net/http"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+
+	"git.omukk.dev/wrenn/sandbox/internal/api"
+	"git.omukk.dev/wrenn/sandbox/internal/config"
+	"git.omukk.dev/wrenn/sandbox/internal/db"
+	"git.omukk.dev/wrenn/sandbox/proto/hostagent/gen/hostagentv1connect"
+)
+
+func main() {
+	slog.SetDefault(slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{
+		Level: slog.LevelDebug,
+	})))
+
+	cfg := config.Load()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	// Database connection pool.
+	pool, err := pgxpool.New(ctx, cfg.DatabaseURL)
+	if err != nil {
+		slog.Error("failed to connect to database", "error", err)
+		os.Exit(1)
+	}
+	defer pool.Close()
+
+	if err := pool.Ping(ctx); err != nil {
+		slog.Error("failed to ping database", "error", err)
+		os.Exit(1)
+	}
+	slog.Info("connected to database")
+
+	queries := db.New(pool)
+
+	// Connect RPC client for the host agent.
+	agentHTTP := &http.Client{Timeout: 10 * time.Minute}
+	agentClient := hostagentv1connect.NewHostAgentServiceClient(
+		agentHTTP,
+		cfg.HostAgentAddr,
+	)
+
+	// API server.
+	srv := api.New(queries, agentClient)
+
+	// Start reconciler.
+	reconciler := api.NewReconciler(queries, agentClient, "default", 30*time.Second)
+	reconciler.Start(ctx)
+
+	httpServer := &http.Server{
+		Addr:    cfg.ListenAddr,
+		Handler: srv.Handler(),
+	}
+
+	// Graceful shutdown on signal.
+	sigCh := make(chan os.Signal, 1)
+	signal.Notify(sigCh, syscall.SIGINT, syscall.SIGTERM)
+	go func() {
+		sig := <-sigCh
+		slog.Info("received signal, shutting down", "signal", sig)
+		cancel()
+
+		shutdownCtx, shutdownCancel := context.WithTimeout(context.Background(), 30*time.Second)
+		defer shutdownCancel()
+
+		if err := httpServer.Shutdown(shutdownCtx); err != nil {
+			slog.Error("http server shutdown error", "error", err)
+		}
+	}()
+
+	slog.Info("control plane starting", "addr", cfg.ListenAddr, "agent", cfg.HostAgentAddr)
+	if err := httpServer.ListenAndServe(); err != nil && err != http.ErrServerClosed {
+		slog.Error("http server error", "error", err)
+		os.Exit(1)
+	}
+
+	slog.Info("control plane stopped")
+}