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Update outdated file dev-1.17-ja.3 #22478

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Original file line number Diff line number Diff line change
Expand Up @@ -27,44 +27,47 @@ Windows applications constitute a large portion of the services and applications
To deploy a Windows container on Kubernetes, you must first create an example application. The example YAML file below creates a simple webserver application. Create a service spec named `win-webserver.yaml` with the contents below:

```yaml
apiVersion: v1
kind: Service
metadata:
name: win-webserver
labels:
app: win-webserver
spec:
ports:
# the port that this service should serve on
- port: 80
targetPort: 80
selector:
app: win-webserver
type: NodePort
---
apiVersion: extensions/v1beta1
kind: Deployment
apiVersion: v1
kind: Service
metadata:
name: win-webserver
labels:
app: win-webserver
spec:
ports:
# the port that this service should serve on
- port: 80
targetPort: 80
selector:
app: win-webserver
type: NodePort
---
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
app: win-webserver
name: win-webserver
spec:
replicas: 2
selector:
matchLabels:
app: win-webserver
template:
metadata:
labels:
app: win-webserver
name: win-webserver
spec:
replicas: 2
template:
metadata:
labels:
app: win-webserver
name: win-webserver
spec:
containers:
- name: windowswebserver
image: mcr.microsoft.com/windows/servercore:ltsc2019
command:
containers:
- name: windowswebserver
image: mcr.microsoft.com/windows/servercore:ltsc2019
command:
- powershell.exe
- -command
- "<#code used from https://gist.github.com/wagnerandrade/5424431#> ; $$listener = New-Object System.Net.HttpListener ; $$listener.Prefixes.Add('http://*:80/') ; $$listener.Start() ; $$callerCounts = @{} ; Write-Host('Listening at http://*:80/') ; while ($$listener.IsListening) { ;$$context = $$listener.GetContext() ;$$requestUrl = $$context.Request.Url ;$$clientIP = $$context.Request.RemoteEndPoint.Address ;$$response = $$context.Response ;Write-Host '' ;Write-Host('> {0}' -f $$requestUrl) ; ;$$count = 1 ;$$k=$$callerCounts.Get_Item($$clientIP) ;if ($$k -ne $$null) { $$count += $$k } ;$$callerCounts.Set_Item($$clientIP, $$count) ;$$ip=(Get-NetAdapter | Get-NetIpAddress); $$header='<html><body><H1>Windows Container Web Server</H1>' ;$$callerCountsString='' ;$$callerCounts.Keys | % { $$callerCountsString+='<p>IP {0} callerCount {1} ' -f $$ip[1].IPAddress,$$callerCounts.Item($$_) } ;$$footer='</body></html>' ;$$content='{0}{1}{2}' -f $$header,$$callerCountsString,$$footer ;Write-Output $$content ;$$buffer = [System.Text.Encoding]::UTF8.GetBytes($$content) ;$$response.ContentLength64 = $$buffer.Length ;$$response.OutputStream.Write($$buffer, 0, $$buffer.Length) ;$$response.Close() ;$$responseStatus = $$response.StatusCode ;Write-Host('< {0}' -f $$responseStatus) } ; "
nodeSelector:
kubernetes.io/os: windows
- "<#code used from https://gist.github.com/wagnerandrade/5424431#> ; $$listener = New-Object System.Net.HttpListener ; $$listener.Prefixes.Add('http://*:80/') ; $$listener.Start() ; $$callerCounts = @{} ; Write-Host('Listening at http://*:80/') ; while ($$listener.IsListening) { ;$$context = $$listener.GetContext() ;$$requestUrl = $$context.Request.Url ;$$clientIP = $$context.Request.RemoteEndPoint.Address ;$$response = $$context.Response ;Write-Host '' ;Write-Host('> {0}' -f $$requestUrl) ; ;$$count = 1 ;$$k=$$callerCounts.Get_Item($$clientIP) ;if ($$k -ne $$null) { $$count = $$k } ;$$callerCounts.Set_Item($$clientIP, $$count) ;$$ip=(Get-NetAdapter | Get-NetIpAddress); $$header='<html><body><H1>Windows Container Web Server</H1>' ;$$callerCountsString='' ;$$callerCounts.Keys | % { $$callerCountsString='<p>IP {0} callerCount {1} ' -f $$ip[1].IPAddress,$$callerCounts.Item($$_) } ;$$footer='</body></html>' ;$$content='{0}{1}{2}' -f $$header,$$callerCountsString,$$footer ;Write-Output $$content ;$$buffer = [System.Text.Encoding]::UTF8.GetBytes($$content) ;$$response.ContentLength64 = $$buffer.Length ;$$response.OutputStream.Write($$buffer, 0, $$buffer.Length) ;$$response.Close() ;$$responseStatus = $$response.StatusCode ;Write-Host('< {0}' -f $$responseStatus) } ; "
nodeSelector:
kubernetes.io/os: windows
```

{{< note >}}
Expand Down Expand Up @@ -101,6 +104,18 @@ Port mapping is also supported, but for simplicity in this example the container
Windows container hosts are not able to access the IP of services scheduled on them due to current platform limitations of the Windows networking stack. Only Windows pods are able to access service IPs.
{{< /note >}}

## Observability

### Capturing logs from workloads

Logs are an important element of observability; they enable users to gain insights into the operational aspect of workloads and are a key ingredient to troubleshooting issues. Because Windows containers and workloads inside Windows containers behave differently from Linux containers, users had a hard time collecting logs, limiting operational visibility. Windows workloads for example are usually configured to log to ETW (Event Tracing for Windows) or push entries to the application event log. [LogMonitor](https://github.com/microsoft/windows-container-tools/tree/master/LogMonitor), an open source tool by Microsoft, is the recommended way to monitor configured log sources inside a Windows container. LogMonitor supports monitoring event logs, ETW providers, and custom application logs, piping them to STDOUT for consumption by `kubectl logs <pod>`.

Follow the instructions in the LogMonitor GitHub page to copy its binaries and configuration files to all your containers and add the necessary entrypoints for LogMonitor to push your logs to STDOUT.

## Using configurable Container usernames

Starting with Kubernetes v1.16, Windows containers can be configured to run their entrypoints and processes with different usernames than the image defaults. The way this is achieved is a bit different from the way it is done for Linux containers. Learn more about it [here](/docs/tasks/configure-pod-container/configure-runasusername/).

## Managing Workload Identity with Group Managed Service Accounts

Starting with Kubernetes v1.14, Windows container workloads can be configured to use Group Managed Service Accounts (GMSA). Group Managed Service Accounts are a specific type of Active Directory account that provides automatic password management, simplified service principal name (SPN) management, and the ability to delegate the management to other administrators across multiple servers. Containers configured with a GMSA can access external Active Directory Domain resources while carrying the identity configured with the GMSA. Learn more about configuring and using GMSA for Windows containers [here](/docs/tasks/configure-pod-container/configure-gmsa/).
Expand All @@ -116,22 +131,114 @@ Users can ensure Windows containers can be scheduled on the appropriate host usi
* kubernetes.io/os = [windows|linux]
* kubernetes.io/arch = [amd64|arm64|...]

If a Pod specification does not specify a nodeSelector like `"beta.kubernetes.io/os": windows`, it is possible the Pod can be scheduled on any host, Windows or Linux. This can be problematic since a Windows container can only run on Windows and a Linux container can only run on Linux. The best practice is to use a nodeSelector.
If a Pod specification does not specify a nodeSelector like `"kubernetes.io/os": windows`, it is possible the Pod can be scheduled on any host, Windows or Linux. This can be problematic since a Windows container can only run on Windows and a Linux container can only run on Linux. The best practice is to use a nodeSelector.

However, we understand that in many cases users have a pre-existing large number of deployments for Linux containers, as well as an ecosystem of off-the-shelf configurations, such as community Helm charts, and programmatic Pod generation cases, such as with Operators. In those situations, you may be hesitant to make the configuration change to add nodeSelectors. The alternative is to use Taints. Because the kubelet can set Taints during registration, it could easily be modified to automatically add a taint when running on Windows only.

For example: `--register-with-taints='os=Win1809:NoSchedule'`
For example: `--register-with-taints='os=windows:NoSchedule'`

By adding a taint to all Windows nodes, nothing will be scheduled on them (that includes existing Linux Pods). In order for a Windows Pod to be scheduled on a Windows node, it would need both the nodeSelector to choose Windows, and the appropriate matching toleration.

```yaml
nodeSelector:
"beta.kubernetes.io/os": windows
kubernetes.io/os: windows
node.kubernetes.io/windows-build: '10.0.17763'
tolerations:
- key: "os"
operator: "Equal"
value: "Win1809"
value: "windows"
effect: "NoSchedule"
```

### Handling multiple Windows versions in the same cluster

The Windows Server version used by each pod must match that of the node. If you want to use multiple Windows
Server versions in the same cluster, then you should set additional node labels and nodeSelectors.

Kubernetes 1.17 automatically adds a new label `node.kubernetes.io/windows-build` to simplify this. If you're running an older version, then it's recommended to add this label manually to Windows nodes.

This label reflects the Windows major, minor, and build number that need to match for compatibility. Here are values used today for each Windows Server version.

| Product Name | Build Number(s) |
|--------------------------------------|------------------------|
| Windows Server 2019 | 10.0.17763 |
| Windows Server version 1809 | 10.0.17763 |
| Windows Server version 1903 | 10.0.18362 |


### Simplifying with RuntimeClass

[RuntimeClass] can be used to simplify the process of using taints and tolerations. A cluster administrator can create a `RuntimeClass` object which is used to encapsulate these taints and tolerations.


1. Save this file to `runtimeClasses.yml`. It includes the appropriate `nodeSelector` for the Windows OS, architecture, and version.

```yaml
apiVersion: node.k8s.io/v1beta1
kind: RuntimeClass
metadata:
name: windows-2019
handler: 'docker'
scheduling:
nodeSelector:
kubernetes.io/os: 'windows'
kubernetes.io/arch: 'amd64'
node.kubernetes.io/windows-build: '10.0.17763'
tolerations:
- effect: NoSchedule
key: os
operator: Equal
value: "windows"
```

1. Run `kubectl create -f runtimeClasses.yml` using as a cluster administrator
1. Add `runtimeClassName: windows-2019` as appropriate to Pod specs

For example:

```yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: iis-2019
labels:
app: iis-2019
spec:
replicas: 1
template:
metadata:
name: iis-2019
labels:
app: iis-2019
spec:
runtimeClassName: windows-2019
containers:
- name: iis
image: mcr.microsoft.com/windows/servercore/iis:windowsservercore-ltsc2019
resources:
limits:
cpu: 1
memory: 800Mi
requests:
cpu: .1
memory: 300Mi
ports:
- containerPort: 80
selector:
matchLabels:
app: iis-2019
---
apiVersion: v1
kind: Service
metadata:
name: iis
spec:
type: LoadBalancer
ports:
- protocol: TCP
port: 80
selector:
app: iis-2019
```

[RuntimeClass]: https://kubernetes.io/docs/concepts/containers/runtime-class/