installer/pkg/config/cluster.go: Default to Flannel

We're having trouble accessing service IPs from pods with host network
namespaces, which was keeping the metrics API from coming up (I think
that's what the problem is ;) and eventually blocking namespace
deletion.  Defaulting to Flannel fixes that issue.

examples/tectonic.aws.yaml

@@ -259,7 +259,7 @@ networking:
   # - "calico-ipip": [ALPHA] enables BGP based networking. Routing and network policy is implemented by Calico. Note this has been tested on baremetal installations only.
   #
   # - "none": disables the installation of any Pod level networking layer provided by Tectonic. By setting this value, users are expected to deploy their own solution to enable network connectivity for Pods and Services.
-  # type: canal
+  # type: flannel
 
 nodePools:
     # The number of etcd nodes to be created.

examples/tectonic.libvirt.yaml

@@ -93,8 +93,7 @@ networking:
   # - "calico-ipip": [ALPHA] enables BGP based networking. Routing and network policy is implemented by Calico. Note this has been tested on baremetal installations only.
   #
   # - "none": disables the installation of any Pod level networking layer provided by Tectonic. By setting this value, users are expected to deploy their own solution to enable network connectivity for Pods and Services.
-  type: canal
-  mtu: 1480
+  # type: flannel
 
 nodePools:
     # The number of etcd nodes to be created.

installer/pkg/config/cluster.go

@@ -69,7 +69,7 @@ var defaultCluster = Cluster{
 		MTU:         "1480",
 		PodCIDR:     "10.2.0.0/16",
 		ServiceCIDR: "10.3.0.0/16",
-		Type:        tectonicnetwork.NetworkCanal,
+		Type:        tectonicnetwork.NetworkFlannel,
 	},
 }
 

tests/smoke/aws/vars/aws-basic.yaml

@@ -28,7 +28,7 @@ master:
     - master
 name: aws-basic
 networking:
-  type: canal
+  type: flannel
 nodePools:
   - count: 3
     name: etcd