var (
// ErrInvTime indicates that the local time has drifted too much
// from the monitored NTP servers.
ErrInvTime = errors.New("local time differs from observed")
// ErrTooFewServers means that the number of trusted servers are
// smaller then the selected num servers to query.
ErrTooFewServers = errors.New("too few ntp servers configured")
// ErrNoResponse indicates that there is an error to communicate with
// the remote NTP servers
ErrNoResponse = errors.New("no ntp response")
// ErrThreshold means that there is no positive threshold value
ErrThreshold = errors.New("no valid server threshold set")
// ErrDeltaTooSmall is referring to when the max delta time is
// smaller than the request timeout which can give unstable behaviour.
ErrDeltaTooSmall = errors.New("delta is too small")
)
func RandomChoice[T any](s []T, n int, r *rand.Rand) []T
RandomChoice returns a random selection of n items from the slice s. The choice is made using a PSEUDO RANDOM selection. If n is greater than len(s), an empty slice is returned.
Config holds the configuration for a NTPMonitor
type Config struct {
RequestAttempts int `yaml:"request_attempts"`
RequestTimeout int `yaml:"request_timeout"`
NumServers int `yaml:"num_servers"`
MaxTimeDelta int `yaml:"max_time_delta"`
ServerThreshold int `yaml:"server_threshold"`
Period int `yaml:"period"`
Servers []string `yaml:"servers"`
}
func LoadConfig(path string) (*Config, error)
LoadConfig reads a yaml file from a provided path, instantiating a new Config object with the vales found. No sanity checking is made of the loaded values.
type LiveNTPClient struct{}
func (c LiveNTPClient) QueryWithOptions(srv string, opts ntp.QueryOptions) (*ntp.Response, error)
type NTPClient interface {
QueryWithOptions(srv string, opts ntp.QueryOptions) (*ntp.Response, error)
}
NTPMonitor compares the local time with a set of trusted NTP servers.
type NTPMonitor struct {
// contains filtered or unexported fields
}
func New(configFile string) (*NTPMonitor, error)
New creates a NTPMonitor, reading the configuration from the provided path.
func NewFromConfig(cfg *Config) (*NTPMonitor, error)
NewFromConfig creates a NTPMonitor from an instantiated configuration.
func NewFromConfigWithClient(cfg *Config, client NTPClient) (*NTPMonitor, error)
func (n *NTPMonitor) Start()
Start the periodic monitor. Once started, it runs until Stop() is called,
func (n *NTPMonitor) Stop()
Stop the monitoring.