Create container web app without setting linux_fx_version - terraform-provider-azure

Question

I would like to create a container web using terraform. I also would like to deploy it from github. So I need to manage the linux_fx_version property there. When I dont set this in terrraform, I get an error when deploying a container
Error: Deployment Failed with Error: Error: This is not a container web app. Please remove inputs like images and configuration-file which are only relevant for container deployment.
When I set the property in terraform, terraform would apply this setting when I change my infrastructur.
Is there any way to mark a web app container based, or setting this property only when it is not set?

Answer 1

If you want to set the linux_fx_version property after the Azure app service provisioned. you could configure a custom container for Azure App Service with az webapp config container set. Also, you could use a local-exec Provisioner to invoke a process on the machine running Terraform.
For example, you can provision a Linux App Service which runs multiple Docker Containers from Docker Compose file.
provisioner "local-exec" {
command =<<EOT
az webapp config set \
--resource-group ${azurerm_resource_group.main.name} \
--name ${azurerm_app_service.main.name} \
--linux-fx-version "COMPOSE|${filebase64("./compose.yml")}"
EOT
}
Otherwise, to create a web app for containers with terraform, you need to use linux_fx_version to define the container to load on start.
If you're not using App Service Slots and Deployments are handled outside of Terraform - it's possible to ignore changes to specific fields in the configuration using ignore_changes within Terraform's lifecycle block, for example:
resource "azurerm_app_service" "test" {
# ...
site_config = {
# ...
linux_fx_version = "DOCKER|appsvcsample/python-helloworld:0.1.2"
}
lifecycle {
ignore_changes = [
"site_config.0.linux_fx_version", # deployments are made outside of Terraform
]
}
}
For more information, read examples of deploying Web App for Containers (Azure App Service) with terraform and examples of using the App Service Resources.