Did a refactor of some of our Bicep template code for our AKS clusters today.
Before, we were using a rather complicated line of code using string interpolation.
var vnetSubnetId = '${resourceId(vnetResourceGroupName, 'Microsoft.Network/virtualNetworks', vnetName)}/subnets/${vnetSubnetName}'
This was hard to read and the Bicep linter gave the following warning in my editor and during deployment:
WARNING: D:\a\1\a\drop\Generic-templates\containers\azure-kubernetes-service\v4.0\templates\aks.bicep(117,7) : Warning use-resource-id-functions: If property “vnetSubnetID” represents a resource ID, it must use a symbolic resource reference, be a parameter or start with one of these functions: extensionResourceId, guid, if, reference, resourceId, subscription, subscriptionResourceId, tenantResourceId. Found nonconforming expression at vnetSubnetID -> vnetSubnetId [https://aka.ms/bicep/linter/use-resource-id-functions]
Using Existing Resources
After some experimentation I managed to fix it as follows:
@description('Virtual Network name')
param vnetName string
@description('Virtual Network resource group name')
param vnetResourceGroupName string
@description('Virtual Network subnet name')
param vnetSubnetName string
// Import the existing vnet and subnet to get the subnet id for deployment
resource vnet 'Microsoft.Network/virtualNetworks@2022-11-01' existing = {
name: vnetName
scope: resourceGroup(vnetResourceGroupName)
}
resource subnet 'Microsoft.Network/virtualNetworks/subnets@2022-11-01' existing = {
name: vnetSubnetName
parent: vnet
}
Interestingly, subnets are not actually a resource in Azure. When you open a Resource Group, it will not be listed under resources. However, they do get a resource id. This posed a challenge, but I solved it by importing the existing VNet as well and setting it as the parent of the subnet.
Now I can access the subnet id by using subnet.id. I need this later when deploying the AKS cluster itself.
Links:
202306231206
https://learn.microsoft.com/en-us/azure/azure-resource-manager/bicep/existing-resource
[[bicep]] [[coding]] [[Azure]]