Terraform output variables as input - azure

Question

I'm new to Terraform and trying to wrap my head around the use of output variables. we are on AKS, and I'm deploying the following resources: resource group, log analytics workspace, Azure Kubernetes. When Log analytics is deployed, I capture the workspace ID into an output variable. Now, when Terraform deploys Kubernetes, it needs to know the workspace ID, how can I pass the output value to the addon_profile (last line in the code below)?
Error:
environment = "${log_analytics_workspace_id.value}"
A managed resource "log_analytics_workspace_id" "value" has not been declared in the root module.
Code:
resource "azurerm_resource_group" "test" {
name = "${var.log}"
location = "${var.location}"
}
resource "azurerm_log_analytics_workspace" "test" {
name = "${var.logname}"
location = "${azurerm_resource_group.loganalytics.location}"
resource_group_name = "${azurerm_resource_group.loganalytics.name}"
sku = "PerGB2018"
retention_in_days = 30
}
**output "log_analytics_workspace_id" {
value = "${azurerm_log_analytics_workspace.test.workspace_id}"
}**
....................................................
addon_profile {
oms_agent {
enabled = true
**log_analytics_workspace_id = "${log_analytics_workspace_id.value}"**
}
}

Answer 1

Terraform's output values are like the "return values" of a module. In order to declare and use the log_analytics_workspace_id output value, you would need to put all of the code for the creation of the resource group, log analytics workspace, and Azure Kubernetes infrastructure into a single Terraform module, and then reference the output value from outside of the module:
# declare your module here, which contains creation code for all your Azure infrastructure + the output variable
module "azure_analytics" {
source = "git::ssh://git#github.com..."
}
# now, you can reference the output variable in your addon_profile from outside the module:
addon_profile {
oms_agent {
enabled = true
log_analytics_workspace_id = "${module.azure_analytics.log_analytics_workspace_id}"
}
}
On the other hand, if you just want to use the workspace_id value from your azurerm_log_analytics_workspace within the same code, just reference it like azurerm_log_analytics_workspace.test.workspace_id.