diff --git a/upup/pkg/api/componentconfig.go b/upup/pkg/api/componentconfig.go
index 1620b98cd0..7a49fc50e6 100644
--- a/upup/pkg/api/componentconfig.go
+++ b/upup/pkg/api/componentconfig.go
@@ -337,11 +337,13 @@ type KubeProxyConfig struct {
 }
 
 type DockerConfig struct {
-	Bridge   string `json:"bridge,omitempty" flag:"bridge"`
-	LogLevel string `json:"logLevel,omitempty" flag:"log-level"`
-	IPTables bool   `json:"ipTables,omitempty" flag:"iptables"`
-	IPMasq   bool   `json:"ipMasq,omitempty" flag:"ip-masq"`
-	Storage  string `json:"storage,omitempty" flag:"s"`
+	Bridge           string `json:"bridge,omitempty" flag:"bridge"`
+	LogLevel         string `json:"logLevel,omitempty" flag:"log-level"`
+	IPTables         bool   `json:"ipTables,omitempty" flag:"iptables"`
+	IPMasq           bool   `json:"ipMasq,omitempty" flag:"ip-masq"`
+	Storage          string `json:"storage,omitempty" flag:"storage-driver"`
+	InsecureRegistry string `json:"insecureRegistry,omitempty" flag:"insecure-registry"`
+	MTU              int    `json:"mtu,omitempty" flag:"mtu"`
 }
 
 type KubeAPIServerConfig struct {
diff --git a/upup/pkg/fi/cloudup/populatecluster_test.go b/upup/pkg/fi/cloudup/populatecluster_test.go
index 510846b3a5..d7526dff58 100644
--- a/upup/pkg/fi/cloudup/populatecluster_test.go
+++ b/upup/pkg/fi/cloudup/populatecluster_test.go
@@ -28,6 +28,26 @@ func buildMinimalCluster() *api.Cluster {
 	return c
 }
 
+func addEtcdClusters(c *api.Cluster) {
+	zones := sets.NewString()
+	for _, z := range c.Spec.Zones {
+		zones.Insert(z.Name)
+	}
+	etcdZones := zones.List()
+
+	for _, etcdCluster := range EtcdClusters {
+		etcd := &api.EtcdClusterSpec{}
+		etcd.Name = etcdCluster
+		for _, zone := range etcdZones {
+			m := &api.EtcdMemberSpec{}
+			m.Name = zone
+			m.Zone = zone
+			etcd.Members = append(etcd.Members, m)
+		}
+		c.Spec.EtcdClusters = append(c.Spec.EtcdClusters, etcd)
+	}
+}
+
 func TestPopulateCluster_Default_NoError(t *testing.T) {
 	c := buildMinimalCluster()
 
@@ -36,25 +56,7 @@ func TestPopulateCluster_Default_NoError(t *testing.T) {
 		t.Fatalf("error from PerformAssignments: %v", err)
 	}
 
-	if len(c.Spec.EtcdClusters) == 0 {
-		zones := sets.NewString()
-		for _, z := range c.Spec.Zones {
-			zones.Insert(z.Name)
-		}
-		etcdZones := zones.List()
-
-		for _, etcdCluster := range EtcdClusters {
-			etcd := &api.EtcdClusterSpec{}
-			etcd.Name = etcdCluster
-			for _, zone := range etcdZones {
-				m := &api.EtcdMemberSpec{}
-				m.Name = zone
-				m.Zone = zone
-				etcd.Members = append(etcd.Members, m)
-			}
-			c.Spec.EtcdClusters = append(c.Spec.EtcdClusters, etcd)
-		}
-	}
+	addEtcdClusters(c)
 
 	registry := buildInmemoryClusterRegistry()
 	_, err = PopulateClusterSpec(c, registry)
@@ -63,6 +65,40 @@ func TestPopulateCluster_Default_NoError(t *testing.T) {
 	}
 }
 
+func TestPopulateCluster_Docker_Spec(t *testing.T) {
+	c := buildMinimalCluster()
+	c.Spec.Docker = &api.DockerConfig{
+		MTU:              5678,
+		InsecureRegistry: "myregistry.com:1234",
+	}
+
+	err := c.PerformAssignments()
+	if err != nil {
+		t.Fatalf("error from PerformAssignments: %v", err)
+	}
+
+	addEtcdClusters(c)
+
+	registry := buildInmemoryClusterRegistry()
+	full, err := PopulateClusterSpec(c, registry)
+	if err != nil {
+		t.Fatalf("Unexpected error from PopulateCluster: %v", err)
+	}
+
+	if full.Spec.Docker.MTU != 5678 {
+		t.Fatalf("Unexpected Docker MTU: %v", full.Spec.Docker.MTU)
+	}
+
+	if full.Spec.Docker.InsecureRegistry != "myregistry.com:1234" {
+		t.Fatalf("Unexpected Docker InsecureRegistry: %v", full.Spec.Docker.InsecureRegistry)
+	}
+
+	// Check default values not changed
+	if full.Spec.Docker.Bridge != "cbr0" {
+		t.Fatalf("Unexpected Docker Bridge: %v", full.Spec.Docker.Bridge)
+	}
+}
+
 func TestPopulateCluster_Custom_CIDR(t *testing.T) {
 	c := buildMinimalCluster()
 	c.Spec.NetworkCIDR = "172.20.2.0/24"
@@ -77,25 +113,7 @@ func TestPopulateCluster_Custom_CIDR(t *testing.T) {
 		t.Fatalf("error from PerformAssignments: %v", err)
 	}
 
-	if len(c.Spec.EtcdClusters) == 0 {
-		zones := sets.NewString()
-		for _, z := range c.Spec.Zones {
-			zones.Insert(z.Name)
-		}
-		etcdZones := zones.List()
-
-		for _, etcdCluster := range EtcdClusters {
-			etcd := &api.EtcdClusterSpec{}
-			etcd.Name = etcdCluster
-			for _, zone := range etcdZones {
-				m := &api.EtcdMemberSpec{}
-				m.Name = zone
-				m.Zone = zone
-				etcd.Members = append(etcd.Members, m)
-			}
-			c.Spec.EtcdClusters = append(c.Spec.EtcdClusters, etcd)
-		}
-	}
+	addEtcdClusters(c)
 
 	registry := buildInmemoryClusterRegistry()
 	full, err := PopulateClusterSpec(c, registry)
@@ -116,25 +134,7 @@ func TestPopulateCluster_IsolateMasters(t *testing.T) {
 		t.Fatalf("error from PerformAssignments: %v", err)
 	}
 
-	if len(c.Spec.EtcdClusters) == 0 {
-		zones := sets.NewString()
-		for _, z := range c.Spec.Zones {
-			zones.Insert(z.Name)
-		}
-		etcdZones := zones.List()
-
-		for _, etcdCluster := range EtcdClusters {
-			etcd := &api.EtcdClusterSpec{}
-			etcd.Name = etcdCluster
-			for _, zone := range etcdZones {
-				m := &api.EtcdMemberSpec{}
-				m.Name = zone
-				m.Zone = zone
-				etcd.Members = append(etcd.Members, m)
-			}
-			c.Spec.EtcdClusters = append(c.Spec.EtcdClusters, etcd)
-		}
-	}
+	addEtcdClusters(c)
 
 	registry := buildInmemoryClusterRegistry()
 	full, err := PopulateClusterSpec(c, registry)
@@ -158,25 +158,7 @@ func TestPopulateCluster_IsolateMastersFalse(t *testing.T) {
 		t.Fatalf("error from PerformAssignments: %v", err)
 	}
 
-	if len(c.Spec.EtcdClusters) == 0 {
-		zones := sets.NewString()
-		for _, z := range c.Spec.Zones {
-			zones.Insert(z.Name)
-		}
-		etcdZones := zones.List()
-
-		for _, etcdCluster := range EtcdClusters {
-			etcd := &api.EtcdClusterSpec{}
-			etcd.Name = etcdCluster
-			for _, zone := range etcdZones {
-				m := &api.EtcdMemberSpec{}
-				m.Name = zone
-				m.Zone = zone
-				etcd.Members = append(etcd.Members, m)
-			}
-			c.Spec.EtcdClusters = append(c.Spec.EtcdClusters, etcd)
-		}
-	}
+	addEtcdClusters(c)
 
 	registry := buildInmemoryClusterRegistry()
 	full, err := PopulateClusterSpec(c, registry)