Network: configure nameservers from DHCP and cloud-config

If dns.override is set, use dns.nameservers from cloud-config over the ones set by DHCP. To reconfigure DNS just restart the network service.

Godeps/Godeps.json

@@ -368,7 +368,7 @@
 		},
 		{
 			"ImportPath": "github.com/rancher/netconf",
-			"Rev": "b9aeb623c8ef9551d79efec57ee059658c1ac89c"
+			"Rev": "02925e7cf5a0f0bb0aa5360ee260ef7378e5eff8"
 		},
 		{
 			"ImportPath": "github.com/ryanuber/go-glob",

Godeps/_workspace/src/github.com/rancher/netconf/types.go

@@ -16,6 +16,7 @@ type InterfaceConfig struct {
 }
 
 type DnsConfig struct {
+	Override    bool     `yaml:"override"`
 	Nameservers []string `yaml:"nameservers,flow,omitempty"`
 	Search      []string `yaml:"search,flow,omitempty"`
 }

cmd/network/network.go

@@ -7,6 +7,7 @@ import (
 
 	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"
@@ -37,7 +38,13 @@ func Main() {
 	}
 	cloudinit.SetHostname(cfg) // ignore error
 	if err := netconf.ApplyNetworkConfigs(&cfg.Rancher.Network); err != nil {
-		log.Fatal(err)
+		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); err != nil {
+			log.Error(err)
+		}
 	}
 	if _, err := os.Create(NETWORK_DONE); err != nil {
 		log.Error(err)

os-config.yml

@@ -244,6 +244,7 @@ rancher:
       volumes:
       - /dev:/host/dev
       - /etc/docker:/etc/docker
+      - /etc/resolv.conf:/etc/resolv.conf
       - /etc/rkt:/etc/rkt
       - /etc/ssl/certs/ca-certificates.crt:/etc/ssl/certs/ca-certificates.crt.rancher
       - /lib/firmware:/lib/firmware