Fix the network blip caused during network creation/deletion (#3438)

Author: madhanrm

parts/k8s/kuberneteswindowssetup.ps1

@@ -346,6 +346,7 @@ c:\k\kubelet.exe --hostname-override=`$env:computername --pod-infra-container-im
 `$global:KubeBinariesVersion = "$global:KubeBinariesVersion"
 `$global:CNIPath = "$global:CNIPath"
 `$global:NetworkMode = "$global:NetworkMode"
+`$global:ExternalNetwork = "ext"
 `$global:CNIConfig = "$global:CNIConfig"
 `$global:HNSModule = "$global:HNSModule"
 `$global:VolumePluginDir = "$global:VolumePluginDir"
@@ -362,21 +363,35 @@ Write-Host "NetworkPlugin azure, starting kubelet."
 netsh advfirewall set allprofiles state off
 # startup the service
 
-`$hnsNetwork = Get-HnsNetwork | ? Type -EQ `$global:NetworkMode.ToLower()
+# Find if the primary external switch network exists. If not create one.
+# This is done only once in the lifetime of the node
+`$hnsNetwork = Get-HnsNetwork | ? Name -EQ `$global:ExternalNetwork
+if (!`$hnsNetwork)
+{
+    Write-Host "Creating a new hns Network"
+    ipmo `$global:HNSModule
+    # Fixme : use a smallest range possible, that will not collide with any pod space
+    New-HNSNetwork -Type `$global:NetworkMode -AddressPrefix "192.168.255.0/30" -Gateway "192.168.255.1" -Name `$global:ExternalNetwork -Verbose
+}
+
+# Find if network created by CNI exists, if yes, remove it
+# This is required to keep the network non-persistent behavior
+# Going forward, this would be done by HNS automatically during restart of the node
 
+`$hnsNetwork = Get-HnsNetwork | ? Name -EQ $global:KubeNetwork
 if (`$hnsNetwork)
 {
-    # Kubelet has been restarted with existing network.
     # Cleanup all containers
     docker ps -q | foreach {docker rm `$_ -f}
-    # cleanup network
+
     Write-Host "Cleaning up old HNS network found"
     Remove-HnsNetwork `$hnsNetwork
     Start-Sleep 10
     `$cnijson = "$global:KubeDir" + "\azure-vnet*"
     remove-item `$cnijson  -ErrorAction SilentlyContinue
 }
 
+# Restart Kubeproxy, which would wait, until the network is created
 Restart-Service Kubeproxy
 
 $KubeletCommandLine
@@ -528,11 +543,12 @@ catch
 `$env:KUBE_NETWORK = "$global:KubeNetwork"
 `$global:NetworkMode = "$global:NetworkMode"
 `$global:HNSModule = "$global:HNSModule"
-`$hnsNetwork = Get-HnsNetwork | ? Type -EQ `$global:NetworkMode.ToLower()
+`$hnsNetwork = Get-HnsNetwork | ? Name -EQ $global:KubeNetwork
 while (!`$hnsNetwork)
 {
+    Write-Host "Waiting for Network [$global:KubeNetwork] to be created . . ."
     Start-Sleep 10
-    `$hnsNetwork = Get-HnsNetwork | ? Type -EQ `$global:NetworkMode.ToLower()
+    `$hnsNetwork = Get-HnsNetwork | ? Name -EQ $global:KubeNetwork
 }
 
 #