Windows support PoC by makhov · Pull Request #1317 · k0sproject/k0smotron

makhov · 2025-12-12T10:45:17Z

Windows workers support for bootstrap controller. It generates user-data as powershell script or AWS compatible "powershell-xml" format (which just wraps the powershell script in xml tags)

Note: this change introduce new spec.provisioner struct to let end-user decide which user-data format to use, which effectively deprecates spec.ignition and moves it to spec.provisioner.ignition

apedriza

wdyt about adding some flavor in the e2e for windows provisioning and use our current AWS nightly workflow?

api/bootstrap/v1beta1/k0s_types.go

apedriza · 2026-01-07T10:40:43Z

api/bootstrap/v1beta1/k0s_types.go


+// ProvisionerSpec defines the provisioner configuration.§
+type ProvisionerSpec struct {
+	Type     provisioner.ProvisioningFormat `json:"type,omitempty"`


we could add +kubebuilder:validation:Enum for static validation about supported types

apedriza · 2026-01-07T10:44:48Z

internal/controller/bootstrap/common.go

 }

-func getProvisioner(ignitionSpec *bootstrapv1.IgnitionSpec) provisioner.Provisioner {
+func getProvisioner(provisionerSpec bootstrapv1.ProvisionerSpec, ignitionSpec *bootstrapv1.IgnitionSpec) provisioner.Provisioner {


what about add some condition here or even some api/admission webhook validation to avoid set/instantiate a widnows provisioner for controller nodes? that way we fail earlier

Done, thanks!

internal/provisioner/powershell_xml.go

apedriza · 2026-01-07T10:54:40Z

internal/provisioner/powershell.go

+	return []byte(content), nil
+}
+
+// GetFormat returns the format 'cloud-config' of the provisioner.


Suggested change

// GetFormat returns the format 'cloud-config' of the provisioner.

// GetFormat returns the format 'powershell' of the provisioner.

apedriza · 2026-01-07T11:17:52Z

internal/controller/bootstrap/common.go

+		return &provisioner.IgnitionProvisioner{
+			Variant:          provisionerSpec.Ignition.Variant,
+			Version:          provisionerSpec.Ignition.Version,
+			AdditionalConfig: provisionerSpec.Ignition.AdditionalConfig,


Possible invalid memory address here?

Fixed, thanks!

apedriza · 2026-01-07T11:25:50Z

Should we add some checks in code about from which k0s version windows provisioning is supported?

apedriza · 2026-01-07T11:32:17Z

another doubt that I have is poweshell vs powershell-xml from my limited knowledge about windows. It is because some windows nodes cannot be provisioned using poweshell format, right? for that reason support for both alternatives?

makhov · 2026-01-07T13:27:54Z

another doubt that I have is poweshell vs powershell-xml from my limited knowledge about windows. It is because some windows nodes cannot be provisioned using poweshell format, right? for that reason support for both alternatives?

It's because different cloud providers support different formats. I wasn't able to test all of them, but cloudbase-init docs claim that they support plain powershell, EC2 format (powershell-xml) and cloud-init format:
https://cloudbase-init.readthedocs.io/en/latest/userdata.html

Should we add some checks in code about from which k0s version windows provisioning is supported?

Yeah, I tried to avoid adding validation webhook for K0sWorkerConfig, but considering number of checks we need - it's unavoidable :)

apedriza · 2026-01-07T14:10:46Z

Yeah, I tried to avoid adding validation webhook for K0sWorkerConfig, but considering number of checks we need - it's unavoidable :)

Ive wrote one in this PR #1312 in case you want to reuse it or merge it first

apedriza · 2026-01-21T12:24:05Z

api/bootstrap/v1beta1/k0s_types.go

+	// +kubebuilder:validation:Optional
+	// +kubebuilder:default="linux"
+	// +kubebuilder:validation:Enum=linux;windows
+	Platform string `json:"platform,omitempty"`


Could we infer the platform from the provisioner type and remove this field? if not, add a new admission rule to avoid an unsupported provider for the choosen platform I think can help.

Or maybe create a top-level field platform and specify there the platform provisioner, defaulting to platform.linux.cloud-init. Just thinking aloud

Cloud-init could be used both for windows and linux with RemoteMachines, so we can't reliably guess. I moved it to the provisioning section, is it better?

* v1beta2. wip Signed-off-by: Alexey Makhov <amakhov@mirantis.com> Signed-off-by: makhov <amakhov@mirantis.com> # Conflicts: # internal/controller/bootstrap/controlplane_bootstrap_controller_test.go # internal/controller/bootstrap/worker_bootstrap_controller_test.go # internal/controller/controlplane/k0s_controlplane_controller_test.go # Conflicts: # config/crd/bases/bootstrap/bootstrap.cluster.x-k8s.io_k0scontrollerconfigs.yaml # config/crd/bases/bootstrap/bootstrap.cluster.x-k8s.io_k0sworkerconfigs.yaml # config/crd/bases/bootstrap/bootstrap.cluster.x-k8s.io_k0sworkerconfigtemplates.yaml # Conflicts: # internal/controller/bootstrap/controlplane_bootstrap_controller_test.go * v1beta2. controlplane api. wip Signed-off-by: Alexey Makhov <amakhov@mirantis.com> Signed-off-by: makhov <amakhov@mirantis.com> # Conflicts: # internal/controller/bootstrap/controlplane_bootstrap_controller_test.go # internal/controller/bootstrap/worker_bootstrap_controller_test.go # internal/controller/controlplane/k0s_controlplane_controller_test.go * v1beta2. controlplane api. wip Signed-off-by: Alexey Makhov <amakhov@mirantis.com> Signed-off-by: makhov <amakhov@mirantis.com> # Conflicts: # internal/controller/bootstrap/controlplane_bootstrap_controller_test.go # internal/controller/bootstrap/worker_bootstrap_controller_test.go # internal/controller/controlplane/k0s_controlplane_controller_test.go * v1beta2. linter fixes Signed-off-by: Alexey Makhov <amakhov@mirantis.com> Signed-off-by: makhov <amakhov@mirantis.com> # Conflicts: # internal/controller/bootstrap/controlplane_bootstrap_controller_test.go # internal/controller/bootstrap/worker_bootstrap_controller_test.go # internal/controller/controlplane/k0s_controlplane_controller_test.go * v1beta2 contracts Signed-off-by: Alexey Makhov <amakhov@mirantis.com> Signed-off-by: makhov <amakhov@mirantis.com> # Conflicts: # internal/controller/bootstrap/controlplane_bootstrap_controller_test.go # internal/controller/bootstrap/worker_bootstrap_controller_test.go # internal/controller/controlplane/k0s_controlplane_controller_test.go * v1beta2 contracts. printcolumns Signed-off-by: Alexey Makhov <amakhov@mirantis.com> Signed-off-by: makhov <amakhov@mirantis.com> * v1beta2 contracts. review fixes Signed-off-by: Alexey Makhov <amakhov@mirantis.com> Signed-off-by: makhov <amakhov@mirantis.com> * v1beta2 contracts. pointers everywhere Signed-off-by: Alexey Makhov <amakhov@mirantis.com> Signed-off-by: makhov <amakhov@mirantis.com> --------- Signed-off-by: Alexey Makhov <amakhov@mirantis.com> Signed-off-by: makhov <amakhov@mirantis.com> # Conflicts: # api/bootstrap/v1beta1/k0s_types.go # api/controlplane/v1beta1/k0s_types.go # config/clusterapi/controlplane/crd/bases/controlplane.cluster.x-k8s.io_k0scontrolplanes.yaml # config/crd/controlplane.cluster.x-k8s.io_k0scontrolplanes.yaml # docs/resource-reference/controlplane.cluster.x-k8s.io-v1beta1.md # internal/controller/controlplane/k0s_controlplane_controller.go # inttest/util/util.go

Signed-off-by: Alexey Makhov <amakhov@mirantis.com> Signed-off-by: makhov <amakhov@mirantis.com> # Conflicts: # config/clusterapi/bootstrap/bases/bootstrap.cluster.x-k8s.io_k0sworkerconfigs.yaml # config/clusterapi/bootstrap/bases/bootstrap.cluster.x-k8s.io_k0sworkerconfigtemplates.yaml # config/crd/bases/bootstrap/bootstrap.cluster.x-k8s.io_k0sworkerconfigs.yaml # config/crd/bases/bootstrap/bootstrap.cluster.x-k8s.io_k0sworkerconfigtemplates.yaml # internal/controller/bootstrap/common.go # internal/controller/bootstrap/controlplane_bootstrap_controller.go # internal/controller/bootstrap/worker_bootstrap_controller.go # internal/controller/bootstrap/worker_bootstrap_controller_test.go # internal/provisioner/provisioner.go

Signed-off-by: Alexey Makhov <amakhov@mirantis.com> Signed-off-by: makhov <amakhov@mirantis.com>

Signed-off-by: Alexey Makhov <amakhov@mirantis.com> Signed-off-by: makhov <amakhov@mirantis.com> # Conflicts: # api/bootstrap/v1beta1/k0s_types.go

Signed-off-by: Alexey Makhov <amakhov@mirantis.com> Signed-off-by: makhov <amakhov@mirantis.com>

apedriza

I would like to final review this. @makhov can you rebase v1beta2 branch? I'm a bit confused with what belongs where. I recently rebase v1beta2 with main

makhov force-pushed the windows-support branch from 38b25a2 to 839df8c Compare December 12, 2025 11:00

makhov force-pushed the windows-support branch 4 times, most recently from 0bde38c to c48a0f1 Compare December 29, 2025 10:01

makhov force-pushed the windows-support branch 4 times, most recently from b0ae235 to 3d710c2 Compare January 5, 2026 11:15

makhov marked this pull request as ready for review January 7, 2026 07:15

makhov requested a review from a team as a code owner January 7, 2026 07:15

apedriza reviewed Jan 7, 2026

View reviewed changes

makhov force-pushed the windows-support branch 11 times, most recently from 6ef709e to 18435c0 Compare January 12, 2026 11:28

apedriza reviewed Jan 21, 2026

View reviewed changes

makhov changed the base branch from main to v1beta2-api-version February 13, 2026 20:37

makhov force-pushed the windows-support branch from af06cb4 to 801192e Compare February 23, 2026 08:04

makhov force-pushed the windows-support branch 3 times, most recently from f85130f to a9c606b Compare February 23, 2026 10:16

makhov force-pushed the v1beta2-api-version branch from 1db9739 to 96078d0 Compare February 23, 2026 11:40

makhov added 7 commits February 23, 2026 14:14

Windows support PoC. Provisioner field

1fd4591

Signed-off-by: Alexey Makhov <amakhov@mirantis.com> Signed-off-by: makhov <amakhov@mirantis.com>

Windows support PoC. Review fixes

d85b60e

Signed-off-by: Alexey Makhov <amakhov@mirantis.com> Signed-off-by: makhov <amakhov@mirantis.com> # Conflicts: # api/bootstrap/v1beta1/k0s_types.go

Windows support PoC. Review fixes

ae44831

Signed-off-by: Alexey Makhov <amakhov@mirantis.com> Signed-off-by: makhov <amakhov@mirantis.com>

Windows support PoC. Platform field

dace7ff

Signed-off-by: Alexey Makhov <amakhov@mirantis.com> Signed-off-by: makhov <amakhov@mirantis.com>

Windows support PoC. Docs and test

5fc3b3c

Signed-off-by: Alexey Makhov <amakhov@mirantis.com> Signed-off-by: makhov <amakhov@mirantis.com>

Windows support PoC. v1beta2

2184969

Signed-off-by: Alexey Makhov <amakhov@mirantis.com> Signed-off-by: makhov <amakhov@mirantis.com>

makhov force-pushed the windows-support branch from a9c606b to 2184969 Compare February 23, 2026 13:08

apedriza force-pushed the v1beta2-api-version branch from 96078d0 to 8c75d2d Compare February 26, 2026 15:22

apedriza reviewed Mar 2, 2026

View reviewed changes

apedriza force-pushed the v1beta2-api-version branch 2 times, most recently from 7b8da8a to 2725e5a Compare March 5, 2026 16:33

	// GetFormat returns the format 'cloud-config' of the provisioner.
	// GetFormat returns the format 'powershell' of the provisioner.

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apedriza commented Jan 7, 2026

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