Fix currentStack is being reset when other site_config values are changed.

[KangDroid]

Background(Problem)

Few months ago, I've submitted PR that fixes current_stack is always being reset every time we update azure app service(windows) infrastructure.

After time passes, I've identified that whenever site_config's value changes - is resets site_config again.
Again, it turns out I had to double-apply all the time whenever I apply updates to Azure infrastructure.

Investigation & Possible Cause

With little golang knowledge and Terraform Azure RM Provider's architecture style, I've found that currentStack variable in internal/services/appservice/helpers/web_app_schema.go : func ExpandSiteConfigWindows is always being reset when site_config expansion starts. - But if metadata.ResourceData.HasChange("site_config.0.application_stack") is false, meaning user did not really intended to modify application_stack - it never expands application_stack and set to empty value and sent empty value to app service.

However, if user intended to change application_stack, it will update application_stack correctly.

Reproduce?

1. Create any windows app service(slot does not matter.)
2. Set site_config value(anything, i.e health_check)
3. Apply - provision infrastructure.
4. After provisioning, modify site_config's value(i.e remove health_check)
5. Apply - provision infrastructure.
6. After provisioning(updating) call terraform plan
7. Notice there is "current_stack" changes.

Solutions

• Get state's configuration
• if state contains ApplicationStack, set currentStack to previously-saved state's value.
• Otherwise, leave it empty string.
• if user really intended to modify application_stack -> https://github.com/uniquegood/terraform-provider-azurerm/blob/d52244c412b2f203cbf7483df6ed2f77559ccad0/internal/services/appservice/helpers/web_app_schema.go#L2919 code will be executed hence it will update application_stack properly.
• If not application_stack will be remained as - is.

Related Issues

• Entrypoint(Issue): Terraform detects and applies changes in azurerm_windows_web_app even though the configuration is not changed #16257
• Issue Reply: Terraform detects and applies changes in azurerm_windows_web_app even though the configuration is not changed #16257 (comment)

Others

Please let me know if I am doing something wrong. Feedbacks, other suggestions are always welcome!
Thanks 👍

[peterprumbach-telekom]

Mentioned the same problem when applying azurerm_windows_web_app
#18636

[sehgalnamit]

Hi, when can we get this PR merged?

[sehgalnamit]

@katbyte Can you please check this PR?

[sehgalnamit]

@jackofallops Can please help to review and merge?
Sorry to chase you but it is blocking our automation with current provider.

[gommo]

Yes, please try get this released. It's affecting us too, where we have to double apply each time

[jackofallops]

Thanks @KangDroid
This LGTM 👍

[github-actions]

This functionality has been released in v3.34.0 of the Terraform Provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

For further feature requests or bug reports with this functionality, please create a new GitHub issue following the template. Thank you!

[gommo]

I just ran 3.34 on our appservice and after applying once, and then rerunning a plan I still get a change showing it wants to turn dotnet 4.0 to dotnetcore core3.1 -
It's like it never sets dotnetcode core3.1 properly in terraform state. The actual appservice is set to 3.1 but terraform never seems to know that? Even after this fix??

https://app.screencast.com/SDKV950PZXVzQ?conversation=N0roBpGiXhD85fw3hJpBxG

Can anyone see what I'm missing?

[sehgalnamit]

I see the issue is with:-

2022-12-15 12:13:28 + application_stack {
2022-12-15 12:13:28 + php_version = "7.4"
2022-12-15 12:13:28 }
2022-12-15 12:13:28 }

application_stack is not getting applied for azurerm-windows-web-app but it is applied for azurerm-linux-web-app
@jackofallops @KangDroid possible to check this issue?

[sehgalnamit]

You can ignore it seems to work for me now.
application_stack = {
current_stack = "dotnet" << I was missing this.
dotnet_version = "v4.0"
}

2022-12-15 13:15:52 ~ site_config {
2022-12-15 13:15:52 # (23 unchanged attributes hidden)
2022-12-15 13:15:52
2022-12-15 13:15:52
2022-12-15 13:15:52 - virtual_application {
2022-12-15 13:15:52 - physical_path = "site\wwwroot" -> null
2022-12-15 13:15:52 - preload = false -> null
2022-12-15 13:15:52 - virtual_path = "/" -> null
2022-12-15 13:15:52 }
2022-12-15 13:15:52 # (1 unchanged block hidden)
2022-12-15 13:15:52 }
2022-12-15 13:15:52 # (2 unchanged blocks hidden)
2022-12-15 13:15:52 }
2022-12-15 13:15:52

Used
terraform {
required_version = ">= 0.14"
required_providers {
azurerm = {
source = "hashicorp/azurerm"
version = "= 3.34.0"
}
}
}

-- Tested
2022-12-15 13:15:51 ~ application_stack {
2022-12-15 13:15:51 ~ dotnet_version = "v7.0" -> "v4.0"
2022-12-15 13:15:51 # (1 unchanged attribute hidden)
2022-12-15 13:15:51 }

[github-actions]

I'm going to lock this pull request because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active contributions.
If you have found a problem that seems related to this change, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.