srvcache

Documentation

Overview

Package srvcache provides a caching SRV lookup service that creates a short term cache of SRV answers - it does not comply with DNS protocols like the timings set by DNS servers, its more a short term - think 5 seconds - buffer to avoid hitting the dns servers repeatedly

Index

• type BasicServer
  • func (s *BasicServer) Host() string
  • func (s *BasicServer) HostPort() string
  • func (s *BasicServer) Port() uint16
  • func (s *BasicServer) Scheme() string
  • func (s *BasicServer) SetHost(host string)
  • func (s *BasicServer) SetPort(port int)
  • func (s *BasicServer) SetScheme(scheme string)
  • func (s *BasicServer) String() string
  • func (s *BasicServer) URL() (u *url.URL, err error)
• type Cache
  • func New(identity string, maxAge time.Duration, resolver Resolver, log *logrus.Entry) *Cache
  • func (c *Cache) LookupSRV(service string, proto string, name string) (cname string, addrs []*net.SRV, err error)
  • func (c *Cache) LookupSrvServers(service string, proto string, name string, scheme string) (s Servers, err error)
• type Resolver
• type Server
  • func NewServer(host string, port int, scheme string) Server
• type Servers
  • func NewServers(s ...Server) Servers
  • func StringHostsToServers(hosts []string, scheme string) (servers Servers, err error)

Types

type BasicServer

type BasicServer struct {
	// contains filtered or unexported fields
}

BasicServer is a representation of a network server host and port, implements Server

func (*BasicServer) Host

func (s *BasicServer) Host() string

Host retrieves the host for the server

func (*BasicServer) HostPort

func (s *BasicServer) HostPort() string

HostPort is a string in hostname:port format

func (*BasicServer) Port

func (s *BasicServer) Port() uint16

Port retrieves the port for the server

func (*BasicServer) Scheme

func (s *BasicServer) Scheme() string

Scheme retrieves the url scheme

func (*BasicServer) SetHost

func (s *BasicServer) SetHost(host string)

SetHost sets the host for the server

func (*BasicServer) SetPort

func (s *BasicServer) SetPort(port int)

SetPort sets the port for the server

func (*BasicServer) SetScheme

func (s *BasicServer) SetScheme(scheme string)

SetScheme sets the url scheme

func (*BasicServer) String

func (s *BasicServer) String() string

String is a string representation of the server in url format

func (*BasicServer) URL

func (s *BasicServer) URL() (u *url.URL, err error)

URL creates a correct url from the server if scheme is known

type Cache

type Cache struct {
	sync.Mutex
	// contains filtered or unexported fields
}

Cache provides a fixed term DNS cache for SRV lookups

func New

func New(identity string, maxAge time.Duration, resolver Resolver, log *logrus.Entry) *Cache

New creates a new Cache

func (*Cache) LookupSRV

func (c *Cache) LookupSRV(service string, proto string, name string) (cname string, addrs []*net.SRV, err error)

LookupSRV has the same signature as net.LookupSRV but performs caching

func (*Cache) LookupSrvServers

func (c *Cache) LookupSrvServers(service string, proto string, name string, scheme string) (s Servers, err error)

LookupSrvServers performs a cached SRV lookup and returns a Servers collection

type Resolver

type Resolver func(service string, proto string, name string) (cname string, addrs []*net.SRV, err error)

Resolver performs dns lookup like net.LookupSRV

type Server

type Server interface {
	Host() string
	SetHost(string)
	Port() uint16
	SetPort(int)
	Scheme() string
	SetScheme(string)
	String() string
	URL() (u *url.URL, err error)
	HostPort() string
}

Server is a Server that can be stored in the collection

func NewServer

func NewServer(host string, port int, scheme string) Server

NewServer creates a new server instance

type Servers

type Servers interface {
	Count() int
	Strings() (urls []string)
	URLs() (urls []*url.URL, err error)
	HostPorts() (hps []string)
	Servers() []Server
	Each(func(Server))
}

Servers is a collection of server urls

func NewServers

func NewServers(s ...Server) Servers

NewServers creates a new server collection

func StringHostsToServers

func StringHostsToServers(hosts []string, scheme string) (servers Servers, err error)

StringHostsToServers converts an array of servers like host:123 into an array of Servers collection

if an empty scheme is given the string will be parsed by a url parser and the embedded scheme will be used, if that does not parse into a valid url then an error will be returned