kubernetes: Windows pods don't have DNS networking when they start running

What happened: I started a Windows pod that ran a command that made DNS requests. The initial DNS request(s) that it made timed out, and then DNS suddenly started working without me doing anything.

Once DNS started working it was stable, and these results were repeatable across pod restarts, leading me to conclude that when Windows pods start running they don’t have DNS networking.

Running:

kubectl logs hello-9cbdb744f-qz6tz

Gave:

Resolve-DnsName : dns.msftncsi.com : This operation returned because the timeout period expired
At line:1 char:33
+ ... 16; ++$i) { Resolve-DnsName -Name 'dns.msftncsi.com' -Type 'A' }; Sta ...
+                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : OperationTimeout: (dns.msftncsi.com:String) [Resolve-DnsName], Win32Exception
    + FullyQualifiedErrorId : ERROR_TIMEOUT,Microsoft.DnsClient.Commands.ResolveDnsName


Name                                           Type   TTL   Section    IPAddress
----                                           ----   ---   -------    --------
dns.msftncsi.com                               A      30    Answer     131.107.255.255
dns.msftncsi.com                               A      30    Answer     131.107.255.255
dns.msftncsi.com                               A      30    Answer     131.107.255.255
dns.msftncsi.com                               A      30    Answer     131.107.255.255
dns.msftncsi.com                               A      30    Answer     131.107.255.255
dns.msftncsi.com                               A      30    Answer     131.107.255.255
dns.msftncsi.com                               A      30    Answer     131.107.255.255
dns.msftncsi.com                               A      30    Answer     131.107.255.255
dns.msftncsi.com                               A      30    Answer     131.107.255.255
dns.msftncsi.com                               A      30    Answer     131.107.255.255
dns.msftncsi.com                               A      30    Answer     131.107.255.255
dns.msftncsi.com                               A      30    Answer     131.107.255.255
dns.msftncsi.com                               A      30    Answer     131.107.255.255
dns.msftncsi.com                               A      30    Answer     131.107.255.255
dns.msftncsi.com                               A      30    Answer     131.107.255.255
dns.msftncsi.com                               A      30    Answer     131.107.255.255

What you expected to happen: I expect that when Windows pods start, their networking would be completely configured and enabled so that DNS works immediately.

My application relies on making network requests on startup, and whilst I can (and probably should) add retry logic, it would be better if k8s was easy and reliable to use.

How to reproduce it (as minimally and precisely as possible): Here’s the .yaml file that I used:

apiVersion: apps/v1
kind: Deployment
metadata:
  namespace: default
  name: hello
spec:
  selector:
    matchLabels:
      app.kubernetes.io/component: hello
  template:
    metadata:
      labels:
        app.kubernetes.io/component: hello
    spec:
      nodeSelector:
        kubernetes.io/os: windows
      containers:
        - name: hello-container
          image: mcr.microsoft.com/windows:10.0.17763.437
          command:
            - powershell.exe
            - -Command
            - for ($i = 0; $i -le 16; ++$i) { Resolve-DnsName -Name 'dns.msftncsi.com' -Type 'A' }; Start-Sleep 3600

Anything else we need to know?:

• On-premise install of k8s
• The Windows nodes all have the following feature gates enabled:
  • WinOverlay
  • WindowsGMSA

Linux master:

• OS (e.g. cat /etc/os-release): Ubuntu 18.10 (Cosmic Cuttlefish)

 Kernel Version:             4.18.0-18-generic   #19-Ubuntu   Tue Apr 2 18:13:16 UTC 2019
 OS Image:                   Ubuntu 18.10
 Operating System:           linux
 Architecture:               amd64
 Container Runtime Version:  docker://18.9.5
 Kubelet Version:            v1.14.1
 Kube-Proxy Version:         v1.14.1

Windows worker:

 Kernel Version:             10.0.17763.437
 OS Image:                   Windows Server 2019 Standard
 Operating System:           windows
 Architecture:               amd64
 Container Runtime Version:  docker://18.9.5
 Kubelet Version:            v1.14.1
 Kube-Proxy Version:         v1.14.1

NetworkMode: overlay

.\flanneld.exe -version
v0.11.0

If you need any more information then please let me know.