Bugfix: Update of Windows vm and vmss with non-empty additional_unattend_config.content

[dominik-lekse]

This pull request fixes a crash when updating a azurerm_virtual_machine or azurerm_virtual_machine_scale_set resource which has been previously created with a value set for content in the additional_unattend_config.

Terraform Version

v0.10.5

Terraform AzureRM Provider Version

0.2.2

Affected Resources

• azurerm_virtual_machine
• azurerm_virtual_machine_scale_set

Steps to reproduce

1. Create Windows virtual machine using azurerm_virtual_machine with a non-empty field content in the additional_unattend_config block such as

additional_unattend_config {
    pass = "oobeSystem"
    component = "Microsoft-Windows-Shell-Setup"
    setting_name = "AutoLogon"
    content = "<AutoLogon><Username>Operations</Username><Password><Value>dRaQuDH7vWZLWFf6</Value></Password><Enabled>true</Enabled><LogonCount>1</LogonCount></AutoLogon>"

• Run terraform apply
• Change any parameter of the Windows VM resource in the Terraform configuration, e.g. the vm_size
• Run terraform apply

Expected Behavior

• After the second terraform apply, the resource should be changed accordingly, e.g. a resize should have been performed

Actual Behavior

• Terraform crashed with the following error message

* azurerm_virtual_machine.test: compute.VirtualMachinesClient#CreateOrUpdate: Failure responding to request: StatusCode=409 -- Original Error: autorest/azure: Service returned an error. Status=409 Code="PropertyChangeNotAllowed" Message="Changing property 'windowsConfiguration.additionalUnattendContent.content' is not allowed."

Cause analysis

• After creating a virtual machine resource, the content field will be returned as nil by the Azure Go SDK
• Therefore the field is saved as an empty string in the state
• The field must not be send to to Azure API as "" but rather as nil (or not in the request)
• Currently the Azure API assumes the field should be changed to an empty string "" which is not allowed

Steps to reproduce via tests

azurerm_virtual_machine

This pull request includes a new test TestAccAzureRMVirtualMachine_windowsMachineResize which resizes a Windows virtual machine with additionalUnattendContent.content set.

Without the changes, the test fails:

make testacc TEST=./azurerm TESTARGS='-run=TestAccAzureRMVirtualMachine_windowsMachineResize'
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./azurerm -v -run=TestAccAzureRMVirtualMachine_windowsMachineResize -timeout 120m
=== RUN   TestAccAzureRMVirtualMachine_windowsMachineResize
--- FAIL: TestAccAzureRMVirtualMachine_windowsMachineResize (462.73s)
	testing.go:434: Step 1 error: Error applying: 1 error(s) occurred:

		* azurerm_virtual_machine.test: 1 error(s) occurred:

		* azurerm_virtual_machine.test: compute.VirtualMachinesClient#CreateOrUpdate: Failure responding to request: StatusCode=409 -- Original Error: autorest/azure: Service returned an error. Status=409 Code="PropertyChangeNotAllowed" Message="Changing property 'windowsConfiguration.additionalUnattendContent.content' is not allowed."
FAIL
exit status 1
FAIL	github.com/terraform-providers/terraform-provider-azurerm/azurerm	462.756s
make: *** [testacc] Error 1

With the changes, the test passes:

make testacc TEST=./azurerm TESTARGS='-run=TestAccAzureRMVirtualMachine_windowsMachineResize'
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./azurerm -v -run=TestAccAzureRMVirtualMachine_windowsMachineResize -timeout 120m
=== RUN   TestAccAzureRMVirtualMachine_windowsMachineResize
--- PASS: TestAccAzureRMVirtualMachine_windowsMachineResize (603.00s)
PASS
ok  	github.com/terraform-providers/terraform-provider-azurerm/azurerm	603.036s

azurerm_virtual_machine_scale_set

This pull request includes a new test TestAccAzureRMVirtualMachineScaleSet_basicWindows_managedDisk_resize which resizes a Windows virtual machine scale set with additionalUnattendContent.content set.

Without the changes, the test fails:

make testacc TEST=./azurerm TESTARGS='-run=TestAccAzureRMVirtualMachineScaleSet_basicWindows_managedDisk_resize'
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./azurerm -v -run=TestAccAzureRMVirtualMachineScaleSet_basicWindows_managedDisk_resize -timeout 120m
=== RUN   TestAccAzureRMVirtualMachineScaleSet_basicWindows_managedDisk_resize
--- FAIL: TestAccAzureRMVirtualMachineScaleSet_basicWindows_managedDisk_resize (514.91s)
	testing.go:434: Step 1 error: Error applying: 1 error(s) occurred:

		* azurerm_virtual_machine_scale_set.test: 1 error(s) occurred:

		* azurerm_virtual_machine_scale_set.test: compute.VirtualMachineScaleSetsClient#CreateOrUpdate: Failure responding to request: StatusCode=409 -- Original Error: autorest/azure: Service returned an error. Status=409 Code="PropertyChangeNotAllowed" Message="Changing property 'windowsConfiguration.additionalUnattendContent.content' is not allowed."
FAIL
exit status 1
FAIL	github.com/terraform-providers/terraform-provider-azurerm/azurerm	514.938s
make: *** [testacc] Error 1

With the changes, the test passes:

make testacc TEST=./azurerm TESTARGS='-run=TestAccAzureRMVirtualMachineScaleSet_basicWindows_managedDisk_resize'
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./azurerm -v -run=TestAccAzureRMVirtualMachineScaleSet_basicWindows_managedDisk_resize -timeout 120m
=== RUN   TestAccAzureRMVirtualMachineScaleSet_basicWindows_managedDisk_resize
--- PASS: TestAccAzureRMVirtualMachineScaleSet_basicWindows_managedDisk_resize (572.55s)
PASS
ok  	github.com/terraform-providers/terraform-provider-azurerm/azurerm	572.578s

[tombuildsstuff]

Hey @dominik-lekse

Thanks for this PR - I've taken a look and this LGTM :)

Thanks!

[tombuildsstuff]

Tests pass:

$ acctests azurerm TestAccAzureRMVirtualMachine_windowsMachineResize
=== RUN   TestAccAzureRMVirtualMachine_windowsMachineResize
--- PASS: TestAccAzureRMVirtualMachine_windowsMachineResize (675.31s)
PASS
ok  	github.com/terraform-providers/terraform-provider-azurerm/azurerm	675.331s

$ acctests azurerm TestAccAzureRMVirtualMachineScaleSet_basicWindows_managedDisk_resize
=== RUN   TestAccAzureRMVirtualMachineScaleSet_basicWindows_managedDisk_resize
--- PASS: TestAccAzureRMVirtualMachineScaleSet_basicWindows_managedDisk_resize (459.46s)
PASS
ok  	github.com/terraform-providers/terraform-provider-azurerm/azurerm	459.490s

[ghost]

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