azure_arm.py: create_node: cannot create windows VM

## Summary

Using the azure_arm provider, I cannot create a windows VM. in the create_node function it has been hardcoded to only support linux VMs (I have commented `#HERE` in the code below).

## Detailed Information

I was able to check the name of the image and see if it is a windows Image (all windows images have image.offer == "WindowsServer") and then set the correct osType with in `create_node`. However, this does not work with AzureVhdImage Images. And that's where I am stuck ...

Also, we also set up authentication assuming a linux machine. when the os is windows we don't need to set `data["properties"]["osProfile"]["linuxConfiguration"] ` for `NodeAuthSSHKey` and also `NodeAuthPassword`.

I tried to make a fix but I couldn't figure how to get the osType from a VHD Image.

Please let me know if you have any insights!

# Stack

Traceback (most recent call last):
node = conn.create_node(name=name, location=location, image=image, size=size, auth=auth, ex_resource_group=resource_group, ex_storage_account=storage_account, ex_blob_container=blob_container, ex_nic=nic)
File "/Library/Python/2.7/site-packages/libcloud/compute/drivers/azure_arm.py", line 672, in create_node
method="PUT")
File "/Library/Python/2.7/site-packages/libcloud/common/azure_arm.py", line 229, in request
method=method, raw=raw)
File "/Library/Python/2.7/site-packages/libcloud/common/base.py", line 636, in request
response = responseCls(**kwargs)
File "/Library/Python/2.7/site-packages/libcloud/common/base.py", line 153, in __init__
headers=self.headers)
libcloud.common.exceptions.BaseHTTPError: [InvalidParameter] The value 'Linux' of parameter 'osDisk.osType' is not allowed. Allowed values are 'Windows'.

# Code:

compute/drivers/azure_arm.py

```
if isinstance(image, AzureVhdImage):
instance_vhd = self._get_instance_vhd(
name=name,
ex_resource_group=ex_resource_group,
ex_storage_account=ex_storage_account,
ex_blob_container=ex_blob_container)
storage_profile = {
"osDisk": {
"name": name,
"osType": "linux", #HERE!
"caching": "ReadWrite",
"createOption": "FromImage",
"image": {
"uri": image.id
},
"vhd": {
"uri": instance_vhd,
}
}
}
if ex_use_managed_disks:
raise LibcloudError(
"Creating managed OS disk from %s image "
"type is not supported." % type(image))
elif isinstance(image, AzureImage):
storage_profile = {
"imageReference": {
"publisher": image.publisher,
"offer": image.offer,
"sku": image.sku,
"version": image.version
},
"osDisk": {
"name": name,
"osType": "linux", #HERE!
"caching": "ReadWrite",
"createOption": "FromImage"
}
}
```
...

```
if isinstance(auth, NodeAuthSSHKey):
data["properties"]["osProfile"]["adminPassword"] = \
binascii.hexlify(os.urandom(20)).decode("utf-8")
data["properties"]["osProfile"]["linuxConfiguration"] = { #HERE!
"disablePasswordAuthentication": "true",
"ssh": {
"publicKeys": [
{
"path": '/home/%s/.ssh/authorized_keys' % (
ex_user_name),
"keyData": auth.pubkey # pylint: disable=no-member
}
]
}
}
elif isinstance(auth, NodeAuthPassword):
data["properties"]["osProfile"]["linuxConfiguration"] = { #HERE!
"disablePasswordAuthentication": "false"
}
data["properties"]["osProfile"]["adminPassword"] = auth.password
else:
raise ValueError(
"Must provide NodeAuthSSHKey or NodeAuthPassword in auth")

```

Start in compute/drivers/azure_arm.py, especially create_node and the AzureVhdImage, AzureImage, NodeAuthSSHKey, and NodeAuthPassword branches shown in the issue. Trace how the image type and authentication data are used, including the Azure error for Windows images. Done means Windows VMs can be created without Linux-only settings while existing Linux VM behavior remains supported.

Written by the indexing model from the issue text.