windows_web_app_(slot)_resource: Fix currentStack is not fetched from state when updating infrastructure using terraform.

[KangDroid]

Background(Problem)

I had some problem with Azure App Service(Windows) that - every time I apply updates to our Azure infrastructure, 'Stack Settings' always being reset.

After being reset, whenever I type terraform plan or terraform apply those plans shows me that I have to add 'Stack Settings' should be applied again. - Even though I already declared 'Stack Settings' in initial updates.

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 variable called currentStack in internal/services/appservice/windows_web_app_resource.go : func update is always set to empty string if site_config is not changed.

By this, I came to personal conclusion: 'Whenever app service resource being updated without site_config, currentStack always set to empty string and applies to actual Azure App Service.' -> and it really did applied 'empty currentStack' to Azure App Service.

Solutions

• Get state's configuration
• if state contains ApplicationStack, set currentStack to previously-saved state's value.
• Otherwise, leave it empty string.

Confirmation

• With provider's version 3.12.0 I've confirmed issue I mentioned above still exists.
• With custom-built version, where my commits are applied, I've confirmed there is no current_stack issue with updating resources.

Related Issues

Best entrypoint I could find was #16257 , but most relevant thread reply would be #16257 (comment) .

Others

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

[katbyte]

Thanks @KangDroid ! LGTM 💯

[github-actions]

This functionality has been released in v3.14.0 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!

[github-actions]

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