os/cmd/network/network.go

package network

import (
	"errors"
	"fmt"
	"net"
	"os"
	"os/exec"

	log "github.com/Sirupsen/logrus"

	"github.com/rancherio/os/config"
	"github.com/rancherio/os/docker"
	"github.com/ryanuber/go-glob"
	"github.com/vishvananda/netlink"
)

func Main() {
	args := os.Args
	if len(args) > 1 {
		fmt.Println("call " + args[0] + " to load network config from rancher.yml config file")
		return
	}
	cfg, err := config.LoadConfig()
	if err != nil {
		log.Fatal(err)
	}
	applyNetworkConfigs(cfg)
}

func applyNetworkConfigs(cfg *config.Config) error {
	links, err := netlink.LinkList()
	if err != nil {
		return err
	}

	//apply network config
	for _, link := range links {
		linkName := link.Attrs().Name
		var match config.InterfaceConfig

		for key, netConf := range cfg.Network.Interfaces {
			if netConf.Match == "" {
				netConf.Match = key
			}

			if netConf.Match == "" {
				continue
			}

			// "" means match has not been found
			if match.Match == "" && matches(linkName, netConf.Match) {
				match = netConf
			}

			if netConf.Match == linkName {
				// Found exact match, use it over wildcard match
				match = netConf
			}
		}

		if match.Match != "" {
			err = applyNetConf(link, match)
			if err != nil {
				log.Errorf("Failed to apply settings to %s : %v", linkName, err)
			}
		}
	}

	if err != nil {
		return err
	}

	//post run
	if cfg.Network.PostRun != nil {
		return docker.StartAndWait(config.DOCKER_SYSTEM_HOST, cfg.Network.PostRun)
	}
	return nil
}

func applyNetConf(link netlink.Link, netConf config.InterfaceConfig) error {
	if netConf.DHCP {
		log.Infof("Running DHCP on %s", link.Attrs().Name)
		cmd := exec.Command("udhcpc", "-i", link.Attrs().Name, "-t", "20", "-n")
		cmd.Stdout = os.Stdout
		cmd.Stderr = os.Stderr
		if err := cmd.Run(); err != nil {
			log.Error(err)
		}
	} else if netConf.Address == "" {
		return nil
	} else {
		addr, err := netlink.ParseAddr(netConf.Address)
		if err != nil {
			return err
		}
		if err := netlink.AddrAdd(link, addr); err != nil {
			log.Error("addr add failed")
			return err
		}
		log.Infof("Set %s on %s", netConf.Address, link.Attrs().Name)
	}

	if netConf.MTU > 0 {
		if err := netlink.LinkSetMTU(link, netConf.MTU); err != nil {
			log.Error("set MTU Failed")
			return err
		}
	}

	if err := netlink.LinkSetUp(link); err != nil {
		log.Error("failed to setup link")
		return err
	}

	if netConf.Gateway != "" {
		gatewayIp := net.ParseIP(netConf.Gateway)
		if gatewayIp == nil {
			return errors.New("Invalid gateway address " + netConf.Gateway)
		}

		route := netlink.Route{
			Scope: netlink.SCOPE_UNIVERSE,
			Gw:    net.ParseIP(netConf.Gateway),
		}
		if err := netlink.RouteAdd(&route); err != nil {
			log.Error("gateway set failed")
			return err
		}

		log.Infof("Set default gateway %s", netConf.Gateway)
	}

	return nil
}

func matches(link, conf string) bool {
	return glob.Glob(conf, link)
}