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ingress-mdns.go
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/
ingress-mdns.go
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package main
import (
"net"
"os"
"os/signal"
"reflect"
"strings"
"syscall"
"time"
docopt "github.com/docopt/docopt-go"
log "github.com/sirupsen/logrus"
v1 "k8s.io/api/core/v1"
k8snet "k8s.io/api/networking/v1"
"k8s.io/apimachinery/pkg/fields"
"k8s.io/client-go/kubernetes"
"k8s.io/client-go/rest"
"k8s.io/client-go/tools/cache"
)
// LocalHostname An Ingress hostname in the .local domain
type LocalHostname struct {
TLS bool
Hostname string
}
func main() {
usage := `ingress-mdns - Broadcast ingress hostnames via mDNS
Usage: ingress-mdns [options]
Options:
--cleartext-port=port External cleartext port
of the ingress controller [default: 80]
--tls-port=port External TLS port
of the ingress controller [default: 443]
--debug Print debugging information
-h, --help show this help
Notes:
The service expects the environment variable $HOST_IP to be set,
it is used to select on which interface the hostnames should be broadcast`
arguments, _ := docopt.ParseDoc(usage)
debug, _ := arguments.Bool("--debug")
if debug {
log.SetLevel(log.DebugLevel)
} else {
log.SetLevel(log.InfoLevel)
}
log.Debug(arguments)
config, err := rest.InClusterConfig()
if err != nil {
panic(err.Error())
}
clientset, err := kubernetes.NewForConfig(config)
if err != nil {
panic(err.Error())
}
broadcastIP := net.ParseIP(os.Getenv("HOST_IP"))
broadcastInterface := getInterfaceByIP(broadcastIP)
var zeroconfServers = map[LocalHostname]*Server{}
defer unregisterAllHostnames(zeroconfServers)
watcher := cache.NewListWatchFromClient(clientset.NetworkingV1().RESTClient(), "ingresses", v1.NamespaceAll, fields.Everything())
log.Debugf("Watching ingresses")
_, controller := cache.NewInformer(watcher, &k8snet.Ingress{}, time.Second*30, cache.ResourceEventHandlerFuncs{
AddFunc: func(obj interface{}) {
hostnames := getIngressHostnames(obj.(*k8snet.Ingress))
registerHostnames(arguments, hostnames, broadcastInterface, zeroconfServers)
},
DeleteFunc: func(obj interface{}) {
hostnames := getIngressHostnames(obj.(*k8snet.Ingress))
unregisterHostnames(hostnames, zeroconfServers)
},
UpdateFunc: func(oldObj interface{}, newObj interface{}) {
oldIngress := oldObj.(*k8snet.Ingress)
newIngress := newObj.(*k8snet.Ingress)
oldHostnames := getIngressHostnames(oldIngress)
newHostnames := getIngressHostnames(newIngress)
if !reflect.DeepEqual(oldHostnames, newHostnames) {
log.Infof("Ingress %v changed, re-registering hostnames", oldIngress.Name)
unregisterHostnames(oldHostnames, zeroconfServers)
registerHostnames(arguments, newHostnames, broadcastInterface, zeroconfServers)
}
},
})
sigs := make(chan os.Signal, 1)
stop := make(chan struct{})
signal.Notify(sigs, os.Interrupt, syscall.SIGTERM, syscall.SIGINT)
go controller.Run(stop)
go func() {
sig := <-sigs
log.Debugf("%v", sig)
close(stop)
}()
<-stop
}
func getInterfaceByIP(broadcastIP net.IP) net.Interface {
ifaces, _ := net.Interfaces()
ifaceIPs := []string{}
for _, iface := range ifaces {
ips := getInterfaceIPs(iface)
for _, ip := range ips {
if net.IP.Equal(ip, broadcastIP) {
log.Debugf("Found interface %v", iface.Name)
return iface
}
ifaceIPs = append(ifaceIPs, ip.String())
}
}
log.Panicf("No interface with IP %v was found, available IPs are:\n%v", broadcastIP, strings.Join(ifaceIPs, "\n"))
panic("")
}
func getInterfaceIPs(iface net.Interface) []net.IP {
ifaceIPs := []net.IP{}
addrs, err := iface.Addrs()
if err != nil {
log.Panic(err.Error())
}
for _, addr := range addrs {
var ifaceIP net.IP
switch v := addr.(type) {
case *net.IPNet:
ifaceIP = v.IP
case *net.IPAddr:
ifaceIP = v.IP
}
ifaceIPs = append(ifaceIPs, ifaceIP)
}
return ifaceIPs
}
func registerHostnames(
arguments docopt.Opts,
hostnames []LocalHostname,
iface net.Interface,
servers map[LocalHostname]*Server,
) {
defer func() {
if r := recover(); r != nil {
// No need to log actual error, log.Panic should have taken care of that
log.Errorf("Failed to register hostnames.")
}
}()
for _, local := range hostnames {
log.Infof("Registering %v", local.Hostname)
port, _ := arguments.Int("--cleartext-port")
if local.TLS {
port, _ = arguments.Int("--tls-port")
}
ifaceIPs := []string{}
for _, ip := range getInterfaceIPs(iface) {
ifaceIPs = append(ifaceIPs, ip.String())
}
server, err := RegisterProxy(
local.Hostname,
"_http._tcp",
"local.",
port,
local.Hostname,
ifaceIPs,
[]string{"path=/"},
[]net.Interface{iface},
)
if err != nil {
log.Panic(err.Error())
}
servers[local] = server
}
}
func unregisterHostnames(hostnames []LocalHostname, servers map[LocalHostname]*Server) {
for _, local := range hostnames {
if server, exists := servers[local]; exists {
log.Infof("Unregistering %v", local.Hostname)
server.Shutdown()
delete(servers, local)
}
}
}
func unregisterAllHostnames(servers map[LocalHostname]*Server) {
for local, server := range servers {
log.Infof("Unregistering %v", local.Hostname)
server.Shutdown()
}
}
func getIngressHostnames(ingress *k8snet.Ingress) []LocalHostname {
// The same ingress can have both cleartext and tls hosts.
// This is not implemented yet, for now we just check for the presence
// of the tls.
tls := ingress.Spec.TLS != nil
hostnames := []LocalHostname{}
for _, rule := range ingress.Spec.Rules {
hostname := rule.Host
if !strings.HasSuffix(hostname, ".local") {
continue
}
hostnames = append(hostnames, LocalHostname{tls, strings.TrimSuffix(hostname, ".local")})
}
return hostnames
}