website/content/en/docs/tasks/configure-pod-container/configure-runasusername.md

---
title: Configure RunAsUserName for Windows pods and containers
content_template: templates/task
weight: 20
---

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{{< feature-state for_k8s_version="v1.16" state="alpha" >}}

This page shows how to enable and use the `RunAsUserName` feature for pods and containers that will run on Windows nodes. This feature is meant to be the Windows equivalent of the Linux-specific `runAsUser` feature, allowing users to run the container entrypoints with a different username that their default ones.

{{< note >}}
Currently this feature is in alpha state. The overall functionality of the feature will not change, but there may be some changes regarding the username validation. Please take this into consideration when testing or adopting this feature.
{{< /note >}}

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You need to have a Kubernetes cluster and the kubectl command-line tool must be configured to communicate with your cluster. The cluster is expected to have Windows worker nodes where pods with containers running Windows workloads will get scheduled.


### Enable the WindowsRunAsUserName feature gate

In the alpha state, the `WindowsRunAsUserName` feature gate needs to be enabled on the `kube-apiserver` service. Without it, the `runAsUserName` field will be dropped from the pod's, container's, and init container's SecurityContexts. See [Feature Gates](/docs/reference/command-line-tools-reference/feature-gates/) for an explanation of enabling feature gates. Please make sure `feature-gates=WindowsRunAsUserName=true` parameter exists in the `kube-apiserver` command line.

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## Set the Username for a Pod

To specify the username with which to execute the Pod's container processes, include the `securityContext` field ([PodSecurityContext](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#podsecuritycontext-v1-core) in the Pod specification, and within it, the `windowsOptions` ([WindowsSecurityContextOptions](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#windowssecuritycontextoptions-v1-core) field containing the `runAsUserName` field.

The Windows security context options that you specify for a Pod apply to all Containers and init Containers in the Pod.

Here is a configuration file for a Windows Pod that has the `runAsUserName` field set:

{{< codenew file="windows/run-as-username-pod.yaml" >}}

Create the Pod:

```shell
kubectl apply -f https://k8s.io/examples/windows/run-as-username-pod.yaml
```

Verify that the Pod's Container is running:

```shell
kubectl get pod run-as-username-pod-demo
```

Get a shell to the running Container:

```shell
kubectl exec -it run-as-username-pod-demo -- powershell
```

Check that the shell is running user the correct username:

```powershell
echo $env:USERNAME
```

The output should be:

```shell
ContainerUser
```


## Set the Username for a Container

To specify the username with which to execute a Container's processes, include the `securityContext` field ([SecurityContext](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#securitycontext-v1-core)) in the Container manifest, and within it, the `windowsOptions` ([WindowsSecurityContextOptions](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#windowssecuritycontextoptions-v1-core) field containing the `runAsUserName` field.

The Windows security context options that you specify for a Container apply only to that individual Container, and they override the settings made at the Pod level.

Here is the configuration file for a Pod that has one Container, and the `runAsUserName` field is set at the Pod level and the Container level:

{{< codenew file="windows/run-as-username-container.yaml" >}}

Create the Pod:

```shell
kubectl apply -f https://k8s.io/examples/windows/run-as-username-container.yaml
```

Verify that the Pod's Container is running:

```shell
kubectl get pod run-as-username-container-demo
```

Get a shell to the running Container:

```shell
kubectl exec -it run-as-username-container-demo -- powershell
```

Check that the shell is running user the correct username (the one set at the Container level):

```powershell
echo $env:USERNAME
```

The output should be:

```shell
ContainerAdministrator
```

## Windows Username limitations

In order to use this feature, the value set in the `runAsUserName` field must be a valid username. It must have the following format: `DOMAIN\USER`, where `DOMAIN\` is optional. Windows user names are case insensitive. Additionally, there are some restrictions regarding the `DOMAIN` and `USER`:

- The `runAsUserName` field cannot be empty, and it cannot contain control characters (ASCII values: `0x00-0x1F`, `0x7F`)
- The `DOMAIN` must be either a NetBios name, or a DNS name, each with their own restrictions:
  - NetBios names: maximum 15 characters, cannot start with `.` (dot), and cannot contain the following characters: `\ / : * ? " < > |`
  - DNS names: maximum 255 characters, contains only alphanumeric characters, dots, and dashes, and it cannot start or end with a `.` (dot) or `-` (dash).
- The `USER` must have at most 20 characters, it cannot contain *only* dots or spaces, and it cannot contain the following characters: `" / \ [ ] : ; | = , + * ? < > @`.

Examples of acceptable values for the `runAsUserName` field: `ContainerAdministrator`, `ContainerUser`, `NT AUTHORITY\NETWORK SERVICE`, `NT AUTHORITY\LOCAL SERVICE`.

For more information about these limtations, check [here](https://support.microsoft.com/en-us/help/909264/naming-conventions-in-active-directory-for-computers-domains-sites-and) and [here](https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.localaccounts/new-localuser?view=powershell-5.1).

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* [Guide for scheduling Windows containers in Kubernetes](/docs/setup/production-environment/windows/user-guide-windows-containers/)
* [Managing Workload Identity with Group Managed Service Accounts (GMSA)](/docs/setup/production-environment/windows/user-guide-windows-containers/#managing-workload-identity-with-group-managed-service-accounts)
* [Configure GMSA for Windows pods and containers](/docs/tasks/configure-pod-container/configure-gmsa/)

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