os/cmd/network/network.go

package network

import (
	"bufio"
	"flag"
	"io/ioutil"
	"os"
	"os/exec"
	"strings"

	log "github.com/Sirupsen/logrus"

	"github.com/docker/libnetwork/resolvconf"
	"github.com/rancher/netconf"
	"github.com/rancher/os/cmd/cloudinit"
	"github.com/rancher/os/config"
)

const (
	NETWORK_DONE     = "/var/run/network.done"
	WAIT_FOR_NETWORK = "wait-for-network"
)

var (
	daemon bool
	flags  *flag.FlagSet
)

func init() {
	flags = flag.NewFlagSet(os.Args[0], flag.ContinueOnError)
	flags.BoolVar(&daemon, "daemon", false, "run dhcpd as daemon")
}

func sendTerm(proc string) {
	cmd := exec.Command("killall", "-TERM", proc)
	cmd.Stderr = os.Stderr
	cmd.Stdout = os.Stdout
	cmd.Run()
}

func Main() {
	flags.Parse(os.Args[1:])

	log.Infof("Running network: daemon=%v", daemon)

	os.Remove(NETWORK_DONE) // ignore error
	cfg, err := config.LoadConfig()
	if err != nil {
		log.Fatal(err)
	}
	hostname, _ := cloudinit.SetHostname(cfg) // ignore error
	log.Infof("Network: hostname: '%s'", hostname)
	if err := netconf.ApplyNetworkConfigs(&cfg.Rancher.Network); err != nil {
		log.Error(err)
	}
	hostname, _ = cloudinit.SetHostname(cfg) // ignore error
	log.Infof("Network: hostname: '%s' (from DHCP, if not set by cloud-config)", hostname)
	if hostname != "" {
		hosts, err := os.Open("/etc/hosts")
		defer hosts.Close()
		if err != nil {
			log.Fatal(err)
		}
		lines := bufio.NewScanner(hosts)
		hostsContent := ""
		for lines.Scan() {
			line := strings.TrimSpace(lines.Text())
			fields := strings.Fields(line)
			if len(fields) > 0 && fields[0] == "127.0.1.1" {
				hostsContent += "127.0.1.1 " + hostname + "\n"
				continue
			}
			hostsContent += line + "\n"
		}
		if err := ioutil.WriteFile("/etc/hosts", []byte(hostsContent), 0600); err != nil {
			log.Error(err)
		}
	}
	if cfg.Rancher.Network.Dns.Override {
		log.WithFields(log.Fields{"nameservers": cfg.Rancher.Network.Dns.Nameservers}).Info("Override nameservers")
		if _, err := resolvconf.Build("/etc/resolv.conf", cfg.Rancher.Network.Dns.Nameservers, cfg.Rancher.Network.Dns.Search, nil); err != nil {
			log.Error(err)
		}
	}
	if f, err := os.Create(NETWORK_DONE); err != nil {
		log.Error(err)
	} else {
		f.Close()
	}
	sendTerm(WAIT_FOR_NETWORK)

	if daemon {
		select {}
	}
}