provider/azurerm: Locking route table on subnet create/delete

[whiskeyjay]

This fix is very similar to #13637 by @tombuildsstuff - a similar error (429) can happen if the route table is being updated while trying to create/delete a subnet that uses the said route table.

Also, added a check in the resource id parser for empty string key or value (this can happen from Import command as users can manually type in a resource id).

The following script can repro the error intermittently:

resource "azurerm_resource_group" "rtTableTests" {
    name = "acctestRG"
    location = "West US"
}

resource "azurerm_virtual_network" "rtTable2" {
    name = "acctestvirtnet"
    address_space = ["10.0.0.0/16"]
    location = "West US"
    resource_group_name = "${azurerm_resource_group.rtTableTests.name}"
    tags {
        environment = "Testing"
    }
}

resource "azurerm_subnet" "rtTable2" {
    name = "acctestsubnet"
    resource_group_name = "${azurerm_resource_group.rtTableTests.name}"
    virtual_network_name = "${azurerm_virtual_network.rtTable2.name}"
    address_prefix = "10.0.2.0/24"
        route_table_id = "${azurerm_route_table.rtTable2.id}"
}

resource "azurerm_route_table" "rtTable2" {
  name                = "rtTable2-RT"
  location            = "West US"
  resource_group_name = "${azurerm_resource_group.rtTableTests.name}"
}

resource "azurerm_route" "route_a" {
  name                = "TestRouteA"
  resource_group_name = "${azurerm_resource_group.rtTableTests.name}"
  route_table_name    = "${azurerm_route_table.rtTable2.name}"

  address_prefix         = "10.100.0.0/14"
  next_hop_type          = "VirtualAppliance"
  next_hop_in_ip_address = "10.10.1.1"
}

Error message is:

Failure responding to request: StatusCode=429 -- Original Error: autorest/azure: Service returned an error. Status=429 Code="RetryableError" Message="A retryable error occured." Details=[{"code":"ReferencedResourceNotProvisioned","message":"Cannot proceed with operation because resource /subscriptions/c3adb315-00d7-4bd0-96be-c96210ced312/resourceGroups/acctestRG/providers/Microsoft.Network/routeTables/rtTable2-RT used by resource /subscriptions/c3adb315-00d7-4bd0-96be-c96210ced312/resourceGroups/acctestRG/providers/Microsoft.Network/virtualNetworks/acctestvirtnet/subnets/acctestsubnet is not in Succeeded state. Resource is in Updating state and the last operation that updated/is updating the resource is PutRouteOperation."}]

Acc test results:

make testacc TEST=./builtin/providers/azurerm/ TESTARGS='-run=TestAccAzureRMSubnet_basic'
==> Checking that code complies with gofmt requirements...
go generate $(go list ./... | grep -v /terraform/vendor/)
2017/04/19 16:19:50 Generated command/internal_plugin_list.go
TF_ACC=1 go test ./builtin/providers/azurerm/ -v -run=TestAccAzureRMSubnet_basic -timeout 120m
=== RUN   TestAccAzureRMSubnet_basic
--- PASS: TestAccAzureRMSubnet_basic (164.72s)
PASS
ok      github.com/hashicorp/terraform/builtin/providers/azurerm    164.735s

make testacc TEST=./builtin/providers/azurerm/ TESTARGS='-run=TestAccAzureRMSubnet_disappears'
==> Checking that code complies with gofmt requirements...
go generate $(go list ./... | grep -v /terraform/vendor/)
2017/04/19 16:24:25 Generated command/internal_plugin_list.go
TF_ACC=1 go test ./builtin/providers/azurerm/ -v -run=TestAccAzureRMSubnet_disappears -timeout 120m
=== RUN   TestAccAzureRMSubnet_disappears
--- PASS: TestAccAzureRMSubnet_disappears (165.17s)
PASS
ok      github.com/hashicorp/terraform/builtin/providers/azurerm    165.184s

[tombuildsstuff]

Hi @whiskeyjay

Thanks for this contribution - it LGTM :)

I noticed a minor issue when running the tests - where the TestAccAzureRMSubnet_importBasic test was failing due to the extra placeholders in the testAccAzureRMSubnet_basic string not being present; so I've pushed a commit to fix that, and now the tests pass as expected:

$ envchain azurerm make testacc TEST=./builtin/providers/azurerm/ TESTARGS='-run=TestAccAzureRMSubnet'
==> Checking that code complies with gofmt requirements...
go generate $(go list ./... | grep -v /terraform/vendor/)
2017/04/20 12:15:31 Generated command/internal_plugin_list.go
TF_ACC=1 go test ./builtin/providers/azurerm/ -v -run=TestAccAzureRMSubnet -timeout 120m
=== RUN   TestAccAzureRMSubnet_importBasic
--- PASS: TestAccAzureRMSubnet_importBasic (188.28s)
=== RUN   TestAccAzureRMSubnet_basic
--- PASS: TestAccAzureRMSubnet_basic (189.03s)
=== RUN   TestAccAzureRMSubnet_disappears
--- PASS: TestAccAzureRMSubnet_disappears (185.91s)
PASS
ok  	github.com/hashicorp/terraform/builtin/providers/azurerm	563.241s

$ make testacc TEST=./builtin/providers/azurerm/ TESTARGS='-run=TestParseAzureResourceID'
==> Checking that code complies with gofmt requirements...
go generate $(go list ./... | grep -v /terraform/vendor/)
2017/04/20 12:27:46 Generated command/internal_plugin_list.go
TF_ACC=1 go test ./builtin/providers/azurerm/ -v -run=TestParseAzureResourceID -timeout 120m
=== RUN   TestParseAzureResourceID
--- PASS: TestParseAzureResourceID (0.00s)
PASS
ok  	github.com/hashicorp/terraform/builtin/providers/azurerm	0.019s

Thanks!

[whiskeyjay]

@tombuildsstuff Good catch, thanks!

[ghost]

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