banger/internal/firecracker/client_test.go

package firecracker

import (
	"bytes"
	"context"
	"log/slog"
	"net"
	"os"
	"path/filepath"
	"strings"
	"testing"
	"time"
)

func TestBuildConfig(t *testing.T) {
	cfg := buildConfig(MachineConfig{
		VMID:            "vm-1",
		SocketPath:      "/tmp/fc.sock",
		LogPath:         "/tmp/fc.log",
		MetricsPath:     "/tmp/fc.metrics",
		KernelImagePath: "/kernel",
		InitrdPath:      "/initrd",
		KernelArgs:      "console=ttyS0",
		Drives: []DriveConfig{
			{ID: "rootfs", Path: "/dev/mapper/root", IsRoot: true},
			{ID: "work", Path: "/var/lib/banger/root.ext4"},
		},
		TapDevice: "tap-fc-1",
		VSockPath: "/tmp/fc.vsock",
		VSockCID:  10042,
		VCPUCount: 4,
		MemoryMiB: 2048,
	})

	if cfg.SocketPath != "/tmp/fc.sock" {
		t.Fatalf("socket path = %q", cfg.SocketPath)
	}
	if cfg.LogPath != "/tmp/fc.log" || cfg.MetricsPath != "/tmp/fc.metrics" {
		t.Fatalf("unexpected log or metrics path: %+v", cfg)
	}
	if cfg.KernelImagePath != "/kernel" || cfg.InitrdPath != "/initrd" {
		t.Fatalf("unexpected kernel paths: %+v", cfg)
	}
	if len(cfg.Drives) != 2 {
		t.Fatalf("drive count = %d, want 2", len(cfg.Drives))
	}
	if cfg.Drives[0].DriveID == nil || *cfg.Drives[0].DriveID != "work" {
		t.Fatalf("work drive id = %v", cfg.Drives[0].DriveID)
	}
	if cfg.Drives[1].DriveID == nil || *cfg.Drives[1].DriveID != "rootfs" {
		t.Fatalf("root drive id = %v", cfg.Drives[1].DriveID)
	}
	if len(cfg.NetworkInterfaces) != 1 {
		t.Fatalf("interface count = %d, want 1", len(cfg.NetworkInterfaces))
	}
	if len(cfg.VsockDevices) != 1 {
		t.Fatalf("vsock count = %d, want 1", len(cfg.VsockDevices))
	}
	if cfg.VsockDevices[0].Path != "/tmp/fc.vsock" || cfg.VsockDevices[0].CID != 10042 {
		t.Fatalf("unexpected vsock config: %+v", cfg.VsockDevices[0])
	}
	if got := cfg.NetworkInterfaces[0].StaticConfiguration.HostDevName; got != "tap-fc-1" {
		t.Fatalf("host dev name = %q", got)
	}
	if cfg.MachineCfg.VcpuCount == nil || *cfg.MachineCfg.VcpuCount != 4 {
		t.Fatalf("vcpu = %v", cfg.MachineCfg.VcpuCount)
	}
	if cfg.MachineCfg.MemSizeMib == nil || *cfg.MachineCfg.MemSizeMib != 2048 {
		t.Fatalf("memory = %v", cfg.MachineCfg.MemSizeMib)
	}
	if cfg.MachineCfg.Smt == nil || *cfg.MachineCfg.Smt {
		t.Fatalf("smt = %v, want false", cfg.MachineCfg.Smt)
	}
}

func TestBuildProcessRunnerInvokesSudoWithDirectArgs(t *testing.T) {
	cmd := buildProcessRunner(MachineConfig{
		BinaryPath: "/repo/firecracker",
		SocketPath: "/tmp/fc.sock",
		VSockPath:  "/tmp/vsock.sock",
		VMID:       "vm-1",
	}, nil)

	// No shell, no string interpolation: the binary path and every flag
	// are independent argv entries. Even if MachineConfig ever carried an
	// attacker-controlled value, there's no shell to interpret it.
	wantArgs := []string{"sudo", "-n", "-E", "/repo/firecracker", "--api-sock", "/tmp/fc.sock", "--id", "vm-1"}
	if !equalStrings(cmd.Args, wantArgs) {
		t.Fatalf("args = %v, want %v", cmd.Args, wantArgs)
	}
	if cmd.Path != "/usr/bin/sudo" && cmd.Path != "sudo" {
		t.Fatalf("command path = %q", cmd.Path)
	}
	if cmd.Cancel != nil {
		t.Fatal("process runner should not be tied to a request context")
	}
}

func TestBuildProcessRunnerOmitsSudoWhenAlreadyRoot(t *testing.T) {
	if os.Geteuid() != 0 {
		t.Skip("requires root to exercise the no-sudo branch")
	}
	cmd := buildProcessRunner(MachineConfig{
		BinaryPath: "/repo/firecracker",
		SocketPath: "/tmp/fc.sock",
		VMID:       "vm-1",
	}, nil)
	wantArgs := []string{"/repo/firecracker", "--api-sock", "/tmp/fc.sock", "--id", "vm-1"}
	if !equalStrings(cmd.Args, wantArgs) {
		t.Fatalf("args = %v, want %v", cmd.Args, wantArgs)
	}
}

func equalStrings(a, b []string) bool {
	if len(a) != len(b) {
		return false
	}
	for i := range a {
		if a[i] != b[i] {
			return false
		}
	}
	return true
}

func TestSDKLoggerBridgeEmitsStructuredDebugLogs(t *testing.T) {
	var buf bytes.Buffer
	logger := slog.New(slog.NewJSONHandler(&buf, &slog.HandlerOptions{Level: slog.LevelDebug}))

	entry := newLogger(logger)
	entry.WithField("vm_id", "vm-1").Info("sdk ready")

	output := buf.String()
	if !strings.Contains(output, `"component":"firecracker_sdk"`) {
		t.Fatalf("output = %q, want firecracker_sdk component", output)
	}
	if !strings.Contains(output, `"vm_id":"vm-1"`) {
		t.Fatalf("output = %q, want vm_id field", output)
	}
	if !strings.Contains(output, `"msg":"sdk ready"`) {
		t.Fatalf("output = %q, want sdk message", output)
	}
}

func TestSDKLoggerBridgeSuppressesDebugAtInfoLevel(t *testing.T) {
	var buf bytes.Buffer
	logger := slog.New(slog.NewJSONHandler(&buf, &slog.HandlerOptions{Level: slog.LevelInfo}))

	entry := newLogger(logger)
	entry.Info("sdk hidden at info")

	if buf.Len() != 0 {
		t.Fatalf("expected info-level logger to suppress sdk debug chatter, got %q", buf.String())
	}
}

func TestHealthVSock(t *testing.T) {
	dir := t.TempDir()
	socketPath := filepath.Join(dir, "fc.vsock")
	listener, err := net.Listen("unix", socketPath)
	if err != nil {
		t.Fatalf("Listen: %v", err)
	}
	defer listener.Close()

	done := make(chan error, 1)
	go func() {
		conn, err := listener.Accept()
		if err != nil {
			done <- err
			return
		}
		defer conn.Close()
		buf := make([]byte, 0, 64)
		tmp := make([]byte, 64)
		for {
			n, err := conn.Read(tmp)
			if err != nil {
				done <- err
				return
			}
			buf = append(buf, tmp[:n]...)
			if strings.Contains(string(buf), "\n") {
				break
			}
		}
		if got := string(buf); got != "CONNECT 42070\n" {
			done <- errUnexpectedString(got)
			return
		}
		if _, err := conn.Write([]byte("OK 55\n")); err != nil {
			done <- err
			return
		}
		buf = buf[:0]
		for {
			n, err := conn.Read(tmp)
			if err != nil {
				done <- err
				return
			}
			buf = append(buf, tmp[:n]...)
			if strings.Contains(string(buf), "\r\n\r\n") {
				break
			}
		}
		if got := string(buf); !strings.Contains(got, "GET /healthz HTTP/1.1\r\n") {
			done <- errUnexpectedString(got)
			return
		}
		_, err = conn.Write([]byte("HTTP/1.1 200 OK\r\nContent-Type: application/json\r\nContent-Length: 15\r\n\r\n{\"status\":\"ok\"}"))
		done <- err
	}()

	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
	defer cancel()
	if err := HealthVSock(ctx, nil, socketPath); err != nil {
		t.Fatalf("HealthVSock: %v", err)
	}
	if err := <-done; err != nil {
		t.Fatalf("server: %v", err)
	}
}

type unexpectedStringError string

func (e unexpectedStringError) Error() string {
	return "unexpected string: " + string(e)
}

func errUnexpectedString(value string) error {
	return unexpectedStringError(value)
}