Use netlink instead of shelling out to weave docker-bridge-ip

prog/weaveproxy/main.go

@@ -12,9 +12,10 @@ import (
 )
 
 var (
-	version           = "(unreleased version)"
-	defaultDockerHost = "unix:///var/run/docker.sock"
-	defaultProcPath   = "/proc"
+	version             = "(unreleased version)"
+	defaultDockerHost   = "unix:///var/run/docker.sock"
+	defaultProcPath     = "/proc"
+	defaultDockerBridge = "docker0"
 )
 
 func main() {
@@ -64,6 +65,11 @@ func main() {
 		Log.Warning("--with-dns option has been removed; DNS is on by default")
 	}
 
+	c.DockerBridge = defaultDockerBridge
+	if dockerBridge := os.Getenv("DOCKER_BRIDGE"); dockerBridge != "" {
+		c.DockerBridge = dockerBridge
+	}
+
 	c.DockerHost = defaultDockerHost
 	if dockerHost := os.Getenv("DOCKER_HOST"); dockerHost != "" {
 		c.DockerHost = dockerHost

proxy/common.go

@@ -36,7 +36,6 @@ func callWeave(args ...string) ([]byte, []byte, error) {
 		}
 	}
 
-	propagateEnv("DOCKER_BRIDGE")
 	propagateEnv("DOCKER_HOST")
 
 	// Propagate WEAVE_DEBUG, to make debugging easier.

proxy/proxy.go

@@ -61,6 +61,7 @@ type Config struct {
 	Version             string
 	WithoutDNS          bool
 	NoMulticastRoute    bool
+	DockerBridge        string
 	DockerHost          string
 	ProcPath            string
 }
@@ -151,11 +152,14 @@ func NewProxy(c Config) (*Proxy, error) {
 	p.client = client.Client
 
 	if !p.WithoutDNS {
-		dockerBridgeIP, stderr, err := callWeave("docker-bridge-ip")
+		netDevs, err := GetBridgeNetDev(c.ProcPath, c.DockerBridge)
 		if err != nil {
-			return nil, fmt.Errorf(string(stderr))
+			return nil, err
 		}
-		p.dockerBridgeIP = string(dockerBridgeIP)
+		if len(netDevs) != 1 || len(netDevs[0].CIDRs) != 1 {
+			return nil, fmt.Errorf("Could not obtain address of %s", c.DockerBridge)
+		}
+		p.dockerBridgeIP = netDevs[0].CIDRs[0].IP.String()
 	}
 
 	p.hostnameMatchRegexp, err = regexp.Compile(c.HostnameMatch)