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Windows Support: NetBIOS and Active Directory LDAP SAMAccountName restrictions on Hostname #2217

Closed rhockenbury closed 1 year ago

rhockenbury commented 4 years ago

User Story

As an operator, I would like to manage windows server worker nodes with the cluster api. Hostnames on windows are limited to 15 characters, and the hostnames that are set by the cluster api (by default in cloud-init metadata) exceed this limit. The cluster api should support a more flexible mechanism of setting hostnames so that shorter hostnames can be set for VMs.

Detailed Description

Netbios requires windows computer names to be 15 characters or fewer (https://support.microsoft.com/en-us/help/909264/naming-conventions-in-active-directory-for-computers-domains-sites-and). Attempting to set hostname with more than 15 characters on a windows machine will result in only the first 15 being used.

When using the machine deployment api object, the machine api object names are derived from the machineset controller (https://github.com/kubernetes-sigs/cluster-api/blob/7884484b621f13f604e74f60053f4214a2f19702/controllers/machineset_controller.go#L434). This name is later used to set the vm name (for example in CAPV - https://github.com/kubernetes-sigs/cluster-api-provider-vsphere/blob/895539d004ea33299435a2c739791e9800d0c2ae/controllers/vspheremachine_controller.go#L320), and then also as the local-hostname in the cloud-init metadata (https://github.com/kubernetes-sigs/cluster-api-provider-vsphere/blob/390c49a23e2b535a27b330e4983c59eb0b42f476/pkg/services/govmomi/service.go#L203).

The machine api object names are prefixed by the name of the machine deployment api object. These names, for example, will be in the form:

workload-cluster-2-md-0-5f77f47487-2c4sq 
workload-cluster-2-md-0-5f77f47487-25xhg

where workload-cluster-2-md-0 is the name of the machine deployment api object. The prefix is appended with 17 extra characters (-5f77f47487-2c4sq, -5f77f47487-25xhg), which will bring the total character count above 15. Notice that setting the deployment api object name to 3 or more characters will guarantee the same first 15 characters, and thus hostname collisions for the nodes. Being able to set the deployment api object name to something more meaningful than what could be expressed in 3 characters would be useful.

My current workaround is to have cloudbase-init invoke an additional script before the join command that reforms the host name and sets it for the vm. This is somewhat undesirable as now the hostname and node api object name are not the same as the vm name. For consistency, it's desired (but not required) that the the vm name (as shown by the cloud provider), the machine api object name, and the node api object name are the same as the hostname of the vm.

Anything else you would like to add:

I realize that windows worker nodes are not officially supported by the cluster api, but I'm mentioning it since it's something that's up for discussion for the cluster-api roadmap (https://github.com/kubernetes-sigs/cluster-api/pull/2148/files#diff-767f66541aad47089dd5ded720dede6bR32).

Another workaround could be use to use the machine api object directly instead of the machine deployment api object, which would directly set the vm name based on the name of the machine api object. However, the benefits of using the machine deployment are lost.

/kind feature

dimatha commented 1 year ago

Hey guys, I just wanted to ask if there are any plans working on this?

jsturtevant commented 1 year ago

I don't think anyone is working on this. Most providers that support Windows have used the trimming of the hostname (https://github.com/kubernetes-sigs/cluster-api/issues/2217#issuecomment-1263991276) at this point, I think.

We haven't had many complaints about this as an approach. Have you run into any issues or have other requirements?

dimatha commented 1 year ago

Thanks for coming back to me @jsturtevant ! Yeah, just tested CAPV 1.5.1 provider and the "fix" is there. It does truncate the hostname! I should have checked it first :( Thanks a lot for your quick update!

vincepri commented 1 year ago

Closing due to inactivity, feel free to reopen if you're ready to pick up the work.

/close

k8s-ci-robot commented 1 year ago

@vincepri: Closing this issue.

In response to [this](https://github.com/kubernetes-sigs/cluster-api/issues/2217#issuecomment-1802014391): >Closing due to inactivity, feel free to reopen if you're ready to pick up the work. > >/close Instructions for interacting with me using PR comments are available [here](https://git.k8s.io/community/contributors/guide/pull-requests.md). If you have questions or suggestions related to my behavior, please file an issue against the [kubernetes/test-infra](https://github.com/kubernetes/test-infra/issues/new?title=Prow%20issue:) repository.