Enhancing --cluster-advertise to support <interface-name>

--cluster-advertise daemon option is enahanced to support <interface-name>
in addition to <ip-address> in order to amke it  automation friendly using
docker-machine.

Signed-off-by: Madhu Venugopal <madhu@docker.com>

api/client/info.go

@@ -107,5 +107,8 @@ func (cli *DockerCli) CmdInfo(args ...string) error {
 		fmt.Fprintf(cli.out, "Cluster store: %s\n", info.ClusterStore)
 	}
 
+	if info.ClusterAdvertise != "" {
+		fmt.Fprintf(cli.out, "Cluster advertise: %s\n", info.ClusterAdvertise)
+	}
 	return nil
 }

api/types/types.go

@@ -219,6 +219,7 @@ type Info struct {
 	ExperimentalBuild  bool
 	ServerVersion      string
 	ClusterStore       string
+	ClusterAdvertise   string
 }
 
 // ExecStartCheck is a temp struct used by execStart

daemon/config.go

@@ -71,7 +71,7 @@ func (config *Config) InstallCommonFlags(cmd *flag.FlagSet, usageFn func(string)
 	cmd.Var(opts.NewListOptsRef(&config.Labels, opts.ValidateLabel), []string{"-label"}, usageFn("Set key=value labels to the daemon"))
 	cmd.StringVar(&config.LogConfig.Type, []string{"-log-driver"}, "json-file", usageFn("Default driver for container logs"))
 	cmd.Var(opts.NewMapOpts(config.LogConfig.Config, nil), []string{"-log-opt"}, usageFn("Set log driver options"))
-	cmd.StringVar(&config.ClusterAdvertise, []string{"-cluster-advertise"}, "", usageFn("Address of the daemon instance to advertise"))
+	cmd.StringVar(&config.ClusterAdvertise, []string{"-cluster-advertise"}, "", usageFn("Address or interface name to advertise"))
 	cmd.StringVar(&config.ClusterStore, []string{"-cluster-store"}, "", usageFn("Set the cluster store"))
 	cmd.Var(opts.NewMapOpts(config.ClusterOpts, nil), []string{"-cluster-store-opt"}, usageFn("Set cluster store options"))
 }

daemon/daemon.go

@@ -767,10 +767,17 @@ func NewDaemon(config *Config, registryService *registry.Service) (daemon *Daemo
 	// initialized, the daemon is registered and we can store the discovery backend as its read-only
 	// DiscoveryWatcher version.
 	if config.ClusterStore != "" && config.ClusterAdvertise != "" {
-		var err error
+		advertise, err := discovery.ParseAdvertise(config.ClusterStore, config.ClusterAdvertise)
-		if d.discoveryWatcher, err = initDiscovery(config.ClusterStore, config.ClusterAdvertise, config.ClusterOpts); err != nil {
+		if err != nil {
+			return nil, fmt.Errorf("discovery advertise parsing failed (%v)", err)
+		}
+		config.ClusterAdvertise = advertise
+		d.discoveryWatcher, err = initDiscovery(config.ClusterStore, config.ClusterAdvertise, config.ClusterOpts)
+		if err != nil {
 			return nil, fmt.Errorf("discovery initialization failed (%v)", err)
 		}
+	} else if config.ClusterAdvertise != "" {
+		return nil, fmt.Errorf("invalid cluster configuration. --cluster-advertise must be accompanied by --cluster-store configuration")
 	}
 
 	d.netController, err = d.initNetworkController(config)

daemon/info.go

@@ -92,6 +92,7 @@ func (daemon *Daemon) SystemInfo() (*types.Info, error) {
 		ExperimentalBuild:  utils.ExperimentalBuild(),
 		ServerVersion:      dockerversion.VERSION,
 		ClusterStore:       daemon.config().ClusterStore,
+		ClusterAdvertise:   daemon.config().ClusterAdvertise,
 	}
 
 	// TODO Windows. Refactor this more once sysinfo is refactored into

integration-cli/docker_cli_info_test.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"net"
 
 	"github.com/docker/docker/pkg/integration/checker"
 	"github.com/docker/docker/utils"
@@ -42,11 +43,57 @@ func (s *DockerSuite) TestInfoDiscoveryBackend(c *check.C) {
 
 	d := NewDaemon(c)
 	discoveryBackend := "consul://consuladdr:consulport/some/path"
-	err := d.Start(fmt.Sprintf("--cluster-store=%s", discoveryBackend), "--cluster-advertise=foo")
+	discoveryAdvertise := "1.1.1.1:2375"
+	err := d.Start(fmt.Sprintf("--cluster-store=%s", discoveryBackend), fmt.Sprintf("--cluster-advertise=%s", discoveryAdvertise))
 	c.Assert(err, checker.IsNil)
 	defer d.Stop()
 
 	out, err := d.Cmd("info")
 	c.Assert(err, checker.IsNil)
 	c.Assert(out, checker.Contains, fmt.Sprintf("Cluster store: %s\n", discoveryBackend))
+	c.Assert(out, checker.Contains, fmt.Sprintf("Cluster advertise: %s\n", discoveryAdvertise))
+}
+
+// TestInfoDiscoveryInvalidAdvertise verifies that a daemon run with
+// an invalid `--cluster-advertise` configuration
+func (s *DockerSuite) TestInfoDiscoveryInvalidAdvertise(c *check.C) {
+	testRequires(c, SameHostDaemon)
+
+	d := NewDaemon(c)
+	discoveryBackend := "consul://consuladdr:consulport/some/path"
+
+	// --cluster-advertise with an invalid string is an error
+	err := d.Start(fmt.Sprintf("--cluster-store=%s", discoveryBackend), "--cluster-advertise=invalid")
+	c.Assert(err, checker.Not(checker.IsNil))
+
+	// --cluster-advertise without --cluster-store is also an error
+	err = d.Start("--cluster-advertise=1.1.1.1:2375")
+	c.Assert(err, checker.Not(checker.IsNil))
+}
+
+// TestInfoDiscoveryAdvertiseInterfaceName verifies that a daemon run with `--cluster-advertise`
+// configured with interface name properly show the advertise ip-address in info output.
+func (s *DockerSuite) TestInfoDiscoveryAdvertiseInterfaceName(c *check.C) {
+	testRequires(c, SameHostDaemon)
+
+	d := NewDaemon(c)
+	discoveryBackend := "consul://consuladdr:consulport/some/path"
+	discoveryAdvertise := "eth0"
+
+	err := d.Start(fmt.Sprintf("--cluster-store=%s", discoveryBackend), fmt.Sprintf("--cluster-advertise=%s:2375", discoveryAdvertise))
+	c.Assert(err, checker.IsNil)
+	defer d.Stop()
+
+	iface, err := net.InterfaceByName(discoveryAdvertise)
+	c.Assert(err, checker.IsNil)
+	addrs, err := iface.Addrs()
+	c.Assert(err, checker.IsNil)
+	c.Assert(len(addrs), checker.GreaterThan, 0)
+	ip, _, err := net.ParseCIDR(addrs[0].String())
+	c.Assert(err, checker.IsNil)
+
+	out, err := d.Cmd("info")
+	c.Assert(err, checker.IsNil)
+	c.Assert(out, checker.Contains, fmt.Sprintf("Cluster store: %s\n", discoveryBackend))
+	c.Assert(out, checker.Contains, fmt.Sprintf("Cluster advertise: %s:2375\n", ip.String()))
 }

pkg/discovery/backends.go

@@ -2,6 +2,7 @@ package discovery
 
 import (
 	"fmt"
+	"net"
 	"strings"
 	"time"
 
@@ -39,6 +40,63 @@ func parse(rawurl string) (string, string) {
 	return parts[0], parts[1]
 }
 
+// ParseAdvertise parses the --cluster-advertise daemon config which accepts
+// <ip-address>:<port> or <interface-name>:<port>
+func ParseAdvertise(store, advertise string) (string, error) {
+	var (
+		iface *net.Interface
+		addrs []net.Addr
+		err   error
+	)
+
+	addr, port, err := net.SplitHostPort(advertise)
+
+	if err != nil {
+		return "", fmt.Errorf("invalid --cluster-advertise configuration: %s: %v", advertise, err)
+	}
+
+	ip := net.ParseIP(addr)
+	// If it is a valid ip-address, use it as is
+	if ip != nil {
+		return advertise, nil
+	}
+
+	// If advertise is a valid interface name, get the valid ipv4 address and use it to advertise
+	ifaceName := addr
+	iface, err = net.InterfaceByName(ifaceName)
+	if err != nil {
+		return "", fmt.Errorf("invalid cluster advertise IP address or interface name (%s) : %v", advertise, err)
+	}
+
+	addrs, err = iface.Addrs()
+	if err != nil {
+		return "", fmt.Errorf("unable to get advertise IP address from interface (%s) : %v", advertise, err)
+	}
+
+	if addrs == nil || len(addrs) == 0 {
+		return "", fmt.Errorf("no available advertise IP address in interface (%s)", advertise)
+	}
+
+	addr = ""
+	for _, a := range addrs {
+		ip, _, err := net.ParseCIDR(a.String())
+		if err != nil {
+			return "", fmt.Errorf("error deriving advertise ip-address in interface (%s) : %v", advertise, err)
+		}
+		if ip.To4() == nil || ip.IsLoopback() {
+			continue
+		}
+		addr = ip.String()
+		break
+	}
+	if addr == "" {
+		return "", fmt.Errorf("couldnt find a valid ip-address in interface %s", advertise)
+	}
+
+	addr = fmt.Sprintf("%s:%s", addr, port)
+	return addr, nil
+}
+
 // New returns a new Discovery given a URL, heartbeat and ttl settings.
 // Returns an error if the URL scheme is not supported.
 func New(rawurl string, heartbeat time.Duration, ttl time.Duration, clusterOpts map[string]string) (Backend, error) {