}

func getRootCertificate(rootCertFile string) (*x509.CertPool, error) {
	var certPool *x509.CertPool
	var rootCert []byte
	var err error

	if rootCertFile != "" {
		rootCert, err = os.ReadFile(rootCertFile)
		if err != nil {
			return nil, err
		}

		certPool = x509.NewCertPool()
		ok := certPool.AppendCertsFromPEM(rootCert)
		if !ok {

// See go.dev/issue/67401.
//
//go:linkname systemRoots
var (
	once           sync.Once
	systemRootsMu  sync.RWMutex
	systemRoots    *CertPool
	systemRootsErr error
	fallbacksSet   bool
)

func systemRootsPool() *CertPool {
	once.Do(initSystemRoots)
	systemRootsMu.RLock()
	defer systemRootsMu.RUnlock()
	return systemRoots
}

func initSystemRoots() {
	systemRootsMu.Lock()

func newCitadelClient(endpoint string, rootCert []byte) (pb.IstioCertificateServiceClient, error) {
	certPool := x509.NewCertPool()
	ok := certPool.AppendCertsFromPEM(rootCert)
	if !ok {
		return nil, fmt.Errorf("failed to append certificates")
	}
	config := tls.Config{
		RootCAs:            certPool,
		InsecureSkipVerify: true, // nolint: gosec // test only code
	}
	transportCreds := credentials.NewTLS(&config)

	endpointUpdateChan chan struct{}
	remoteCaCertPool   *x509.CertPool
	meshConfig         mesh.Watcher
}

var (
	trustBundleLog = log.RegisterScope("trustBundle", "Workload mTLS trust bundle logs")
	remoteTimeout  = 10 * time.Second
)

// NewTrustBundle returns a new trustbundle
func NewTrustBundle(remoteCaCertPool *x509.CertPool, meshConfig mesh.Watcher) *TrustBundle {
	var err error
	tb := &TrustBundle{

func Enabled(kvs config.KVS) bool {
	endpoints := kvs.Get(Endpoints)
	return endpoints != ""
}

// LookupConfig - Initialize new etcd config.
func LookupConfig(kvs config.KVS, rootCAs *x509.CertPool) (Config, error) {
	cfg := Config{}
	if err := config.CheckValidKeys(config.EtcdSubSys, kvs, DefaultKVS); err != nil {
		return cfg, err
	}

	endpoints := env.Get(EnvEtcdEndpoints, kvs.Get(Endpoints))

	LookupHost  LookupHost  // Custom lookupHost, is nil on containerized deployments.
	DialTimeout time.Duration

	// TLS Settings
	RootCAs          *x509.CertPool
	CipherSuites     []uint16
	CurvePreferences []tls.CurveID

	// HTTP2
	EnableHTTP2 bool

	// TCP Options
	TCPOptions TCPOptions
}

func Enabled(kvs config.KVS) bool {
	return kvs.Get(ServerAddr) != ""
}

// Lookup - initializes LDAP config, overrides config, if any ENV values are set.
func Lookup(s config.Config, rootCAs *x509.CertPool) (l Config, err error) {
	l = Config{}

	// Purge all removed keys first
	kvs := s[config.IdentityLDAPSubSys][config.Default]
	if len(kvs) > 0 {
		for _, k := range removedKeys {
			kvs.Delete(k)
		}

	Password             string         `json:"password"`
	MaxReconnectInterval time.Duration  `json:"reconnectInterval"`
	KeepAlive            time.Duration  `json:"keepAliveInterval"`
	RootCAs              *x509.CertPool `json:"-"`
	QueueDir             string         `json:"queueDir"`
	QueueLimit           uint64         `json:"queueLimit"`
}

// Validate MQTTArgs fields
func (m MQTTArgs) Validate() error {
	if !m.Enable {