// Retrieve the MX records for miek.nl.
func ExampleMX() {
config, _ := dns.ClientConfigFromFile("/etc/resolv.conf")
c := new(dns.Client)
m := new(dns.Msg)
m.SetQuestion("miek.nl.", dns.TypeMX)
m.RecursionDesired = true
r, _, err := c.Exchange(m, config.Servers[0]+":"+config.Port)
if err != nil {
return
}
if r.Rcode != dns.RcodeSuccess {
return
}
for _, a := range r.Answer {
if mx, ok := a.(*dns.MX); ok {
fmt.Printf("%s\n", mx.String())
}
}
}
// Retrieve the DNSKEY records of a zone and convert them
// to DS records for SHA1, SHA256 and SHA384.
func ExampleDS(zone string) {
config, _ := dns.ClientConfigFromFile("/etc/resolv.conf")
c := new(dns.Client)
m := new(dns.Msg)
if zone == "" {
zone = "miek.nl"
}
m.SetQuestion(dns.Fqdn(zone), dns.TypeDNSKEY)
m.SetEdns0(4096, true)
r, _, err := c.Exchange(m, config.Servers[0]+":"+config.Port)
if err != nil {
return
}
if r.Rcode != dns.RcodeSuccess {
return
}
for _, k := range r.Answer {
if key, ok := k.(*dns.DNSKEY); ok {
for _, alg := range []uint8{dns.SHA1, dns.SHA256, dns.SHA384} {
fmt.Printf("%s; %d\n", key.ToDS(alg).String(), key.Flags)
}
}
}
}
// ConfigureNetworking is called once during host startup and passed the
// strategy and identifier of the networking coordinatior job. Currently the
// only strategy implemented uses flannel.
func (l *LibvirtLXCBackend) ConfigureNetworking(config *host.NetworkConfig) error {
var err error
l.bridgeAddr, l.bridgeNet, err = net.ParseCIDR(config.Subnet)
if err != nil {
return err
}
l.ipalloc.RequestIP(l.bridgeNet, l.bridgeAddr)
err = netlink.CreateBridge(bridgeName, false)
bridgeExists := os.IsExist(err)
if err != nil && !bridgeExists {
return err
}
bridge, err := net.InterfaceByName(bridgeName)
if err != nil {
return err
}
if !bridgeExists {
// We need to explicitly assign the MAC address to avoid it changing to a lower value
// See: https://github.com/flynn/flynn/issues/223
b := random.Bytes(5)
bridgeMAC := fmt.Sprintf("fe:%02x:%02x:%02x:%02x:%02x", b[0], b[1], b[2], b[3], b[4])
if err := netlink.NetworkSetMacAddress(bridge, bridgeMAC); err != nil {
return err
}
}
currAddrs, err := bridge.Addrs()
if err != nil {
return err
}
setIP := true
for _, addr := range currAddrs {
ip, net, _ := net.ParseCIDR(addr.String())
if ip.Equal(l.bridgeAddr) && net.String() == l.bridgeNet.String() {
setIP = false
} else {
if err := netlink.NetworkLinkDelIp(bridge, ip, net); err != nil {
return err
}
}
}
if setIP {
if err := netlink.NetworkLinkAddIp(bridge, l.bridgeAddr, l.bridgeNet); err != nil {
return err
}
}
if err := netlink.NetworkLinkUp(bridge); err != nil {
return err
}
network, err := l.libvirt.LookupNetworkByName(libvirtNetName)
if err != nil {
// network doesn't exist
networkConfig := <.Network{
Name: libvirtNetName,
Bridge: lt.Bridge{Name: bridgeName},
Forward: lt.Forward{Mode: "bridge"},
}
network, err = l.libvirt.NetworkDefineXML(string(networkConfig.XML()))
if err != nil {
return err
}
}
active, err := network.IsActive()
if err != nil {
return err
}
if !active {
if err := network.Create(); err != nil {
return err
}
}
if defaultNet, err := l.libvirt.LookupNetworkByName("default"); err == nil {
// The default network causes dnsmasq to run and bind to all interfaces,
// including ours. This prevents discoverd from binding its DNS server.
// We don't use it, so destroy it if it exists.
defaultNet.Destroy()
}
// enable IP forwarding
if err := ioutil.WriteFile("/proc/sys/net/ipv4/ip_forward", []byte("1\n"), 0644); err != nil {
return err
}
// Set up iptables for outbound traffic masquerading from containers to the
// rest of the network.
if err := iptables.EnableOutboundNAT(bridgeName, l.bridgeNet.String()); err != nil {
return err
}
// Read DNS config, discoverd uses the nameservers
dnsConf, err := dns.ClientConfigFromFile("/etc/resolv.conf")
if err != nil {
return err
}
config.Resolvers = dnsConf.Servers
// Write a resolv.conf to be bind-mounted into containers pointing at the
// future discoverd DNS listener
if err := os.MkdirAll("/etc/flynn", 0755); err != nil {
return err
}
var resolvSearch string
if len(dnsConf.Search) > 0 {
resolvSearch = fmt.Sprintf("search %s\n", strings.Join(dnsConf.Search, " "))
}
if err := ioutil.WriteFile("/etc/flynn/resolv.conf", []byte(fmt.Sprintf("%snameserver %s\n", resolvSearch, l.bridgeAddr.String())), 0644); err != nil {
return err
}
l.resolvConf = "/etc/flynn/resolv.conf"
// Allocate IPs for running jobs
for i, container := range l.containers {
if !container.job.Config.HostNetwork {
var err error
l.containers[i].IP, err = l.ipalloc.RequestIP(l.bridgeNet, container.IP)
if err != nil {
grohl.Log(grohl.Data{"fn": "ConfigureNetworking", "at": "request_ip", "status": "error", "err": err})
}
}
}
close(l.networkConfigured)
return nil
}