host daemon touches (#4)

* feat: launch config tests

* feat: readiness probe port alignment

internal/firecracker/launch_test.go

@@ -0,0 +1,95 @@
+package firecracker
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestLaunchJailedFirecrackerPassesDaemonAndLoggingFlags(t *testing.T) {
+	root := t.TempDir()
+	argsPath := filepath.Join(root, "args.txt")
+	jailerPath := filepath.Join(root, "fake-jailer.sh")
+	script := "#!/bin/sh\nprintf '%s\n' \"$@\" > " + shellQuote(argsPath) + "\n"
+	if err := os.WriteFile(jailerPath, []byte(script), 0o755); err != nil {
+		t.Fatalf("write fake jailer: %v", err)
+	}
+
+	paths, err := buildMachinePaths(root, "vm-1", "/usr/bin/firecracker")
+	if err != nil {
+		t.Fatalf("build machine paths: %v", err)
+	}
+	if err := os.MkdirAll(paths.LogDir, 0o755); err != nil {
+		t.Fatalf("create log dir: %v", err)
+	}
+
+	if _, err := launchJailedFirecracker(paths, "vm-1", "/usr/bin/firecracker", jailerPath); err != nil {
+		t.Fatalf("launch jailed firecracker: %v", err)
+	}
+
+	args := waitForFileContents(t, argsPath)
+	for _, want := range []string{
+		"--daemonize",
+		"--new-pid-ns",
+		"--log-path",
+		paths.JailedFirecrackerLogPath,
+		"--show-level",
+		"--show-log-origin",
+	} {
+		if !containsLine(args, want) {
+			t.Fatalf("missing launch argument %q in %v", want, args)
+		}
+	}
+}
+
+func TestWaitForPIDFileReadsPID(t *testing.T) {
+	pidFilePath := filepath.Join(t.TempDir(), "firecracker.pid")
+	if err := os.WriteFile(pidFilePath, []byte("4321\n"), 0o644); err != nil {
+		t.Fatalf("write pid file: %v", err)
+	}
+
+	pid, err := waitForPIDFile(context.Background(), pidFilePath)
+	if err != nil {
+		t.Fatalf("wait for pid file: %v", err)
+	}
+	if pid != 4321 {
+		t.Fatalf("pid mismatch: got %d want %d", pid, 4321)
+	}
+}
+
+func waitForFileContents(t *testing.T, path string) []string {
+	t.Helper()
+
+	timeout := time.NewTimer(2 * time.Second)
+	defer timeout.Stop()
+	ticker := time.NewTicker(10 * time.Millisecond)
+	defer ticker.Stop()
+
+	for {
+		payload, err := os.ReadFile(path)
+		if err == nil {
+			return strings.Split(strings.TrimSpace(string(payload)), "\n")
+		}
+		select {
+		case <-timeout.C:
+			t.Fatalf("timed out waiting for %q", path)
+		case <-ticker.C:
+		}
+	}
+}
+
+func containsLine(lines []string, want string) bool {
+	for _, line := range lines {
+		if line == want {
+			return true
+		}
+	}
+	return false
+}
+
+func shellQuote(value string) string {
+	return "'" + strings.ReplaceAll(value, "'", "'\"'\"'") + "'"
+}