Changing an application gateway's subnet fails.

[wimpienortje]

Terraform Version

Terraform v0.11.2

• provider.azurerm v1.0.1

Affected Resource(s)

azurerm_application_gateway

Terraform Configuration Files

Use the application gateway example from the documentation. Here (https://www.terraform.io/docs/providers/azurerm/r/application_gateway.html#example-usage)

Output

An execution plan has been generated and is shown below.
Resource actions are indicated with the following symbols:
  ~ update in-place

Terraform will perform the following actions:

  ~ azurerm_application_gateway.network
      gateway_ip_configuration.0.subnet_id: "/subscriptions/....../subnets/my-subnet-1" => "/subscriptions/......./subnets/my-subnet-2"


Plan: 0 to add, 1 to change, 0 to destroy.

Do you want to perform these actions?
  Terraform will perform the actions described above.
  Only 'yes' will be accepted to approve.

  Enter a value: yes

azurerm_application_gateway.network: Modifying... (ID: /subscriptions/...nGateways/my-application-gateway-12345)
  gateway_ip_configuration.0.subnet_id: "/subscriptions/......./subnets/my-subnet-1" => "/subscriptions/........./subnets/my-subnet-2"

Error: Error applying plan:

1 error(s) occurred:

* azurerm_application_gateway.network: 1 error(s) occurred:

* azurerm_application_gateway.network: Error Creating/Updating ApplicationGateway network.ApplicationGatewaysClient#CreateOrUpdate: Failure responding to request: StatusCode=400 -- Original Error: autorest/azure: Service returned an error. Status=400 Code="ApplicationGatewayIpCofigSubnetCannotBeChanged" Message="Subnet referenced by GatewayIpConfiguration /subscriptions/......../providers/Microsoft.Network/applicationGateways/my-application-gateway-12345/gatewayIPConfigurations/my-gateway-ip-configuration cannot be changed. Gateway has to be in Stopped state." Details=[]

Expected Behavior

The application gateway should be stopped, moved to the new subnet and then restarted.

Actual Behavior

Got an error from Azure that says the application gateway must be stopped before its subnet can be changed. Terraform does not provide the functionality to do so, had to resort to az network application-gateway stop to stop the gateway and then terraform apply again.

Steps to Reproduce

1. Create a configuration from the the application gateway example (https://www.terraform.io/docs/providers/azurerm/r/application_gateway.html#example-usage)
2. terraform apply
3. Update configuration to move gateway from subnet-1 to subnet-2.
4. terraform apply

[achandmsft]

@tombuildsstuff could be related to the other app-gateway issue around subnet deletion? #608

[tombuildsstuff]

@achandmsft kind of, but not really - the field needs to become ForceNew, unless this functionality is available in the Portal. That said, we're unable to add a test case for any fix for this until #608 is resolved unfortunately - (since it causes subnet 'leaks' where they can't be deleted until an unspecified period after the Application Gateway's been deleted) - which is why we can't really add a fix this until #608 is resolved.

[tombuildsstuff]

👋

To give an update here: we're still waiting for the Application Gateway API to be fixed before proceeding with any enhancements or bug fixes for this resource; once the API is fixed (I've just requested an update). As such I've de-prioritised this issue for the moment, but we'll circle around and take another look once the API's in a usable state - sorry for the inconvenience here!

Thanks!

[tombuildsstuff]

hi @wimpienortje

Given this issue is blocked on an upstream issue in the Azure API rather than keeping multiple issues open and trying to ensure they all remain up to date - I'm going to close this in favour of #1576 which is the Meta-Issue tracking the Bugs and Enhancements for the Application Gateway Resource. Once the bug in the API is fixed we should be able to take a look into this, but we'll keep track of the status of this issue there for the moment.

Thanks!

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. If you feel I made an error 🤖 🙉 , please reach out to my human friends 👉 hashibot-feedback@hashicorp.com. Thanks!