While using the below code, I was able to successfully create a resource when the tfvars list has only one resource. It fails to create a plan when it has more than one resource.
During the testing, I also noticed that if both the resources has similar configuration (keys) under settings, then plan is getting generated.

In the following example, plan is failing because of “always_on” is added to the second resource. Is there any way to solve this issue?

Providers: AzureRM 3.98.0, terraform version – 1.7.5

Error: The given value is not valid for variable “appservicelist”: collection elements cannot be unified.

env.auto.tfvars
appservicelist = {
    appsvc1 = {
        appsvcname = "appsvctest01"
        rgname = "appsvcrg01"
        settings = {
            site_config = {
                minimum_tls_version = "1.2"
                http2_enabled       = true
                application_stack = {
                    java_version = "17"
                }
            }
        }
    },
    appsvc2 = {
        appsvcname = "appsvctest02"
        rgname = "appsvcrg02"
        settings = {
            site_config = {
                minimum_tls_version = "1.2"
                http2_enabled       = true
                always_on           = true
                application_stack = {
                    java_version = "17"
                }
            }
        }
    }
}

main.tf

module "appservice" {
    for_each = var.appservicelist
    source = "./modules/appservice"
    appsvcname  = each.value.appsvcname
    rgname      = each.value.rgname
    settings    = each.value.settings
}

variables.tf

variables "appservicelist" {
    type = map(object({
        appsvcname = string
        rgname = string
        settings = any
    }) )
}

./modules/appservice/main.tf

resource "azurerm_linux_web_app" "appservice" {
    name = var.appsvcname
    rgname = var.rgname

    dynamic "site_config" {
        for_each = lookup(var.settings, "site_config", {}) != {} ? [1] : []
        content {
            always_on = lookup(var.settings.site_config, "always_on", false)
            http2_enabled = lookup(var.settings.site_config, "http2_enabled", false)
            minimum_tls_version = lookup(var.settings.site_config, "http2_enabled", null)
            ...
            ...
        }

        dynamic "application_stack" {
            for_each = lookup(var.settings.site_config, "application_stack" {}) != {} ? [1] : []
            content {
                java_version = lookup(var.settings.site_config.application_stack, "java_version", null)
            }
        }
    }
}

./modules/appservice/variables.tf

variables "appsvcname" {}
variables "rgname" {}
variables "settings" {
    type = any
    default = {}
}