Enable storage account encryption in install-config
------------------
platform:
  azure:
    region: centralus
    baseDomainResourceGroupName: os4-common
    customerManagedKey:
      keyVault:
        keyName: ci-op-5cg5phi0-4ab29-key
        name: ci-op-5cg5phi0-4ab29-kv
        resourceGroup: ci-op-5cg5phi0-4ab29-rg
      userAssignedIdentityKey: ci-op-5cg5phi0-4ab29-identity

Installer failed with below error:
----------------------
time="2023-12-10T12:31:36Z" level=error msg="Error: Reference to undeclared input variable"
time="2023-12-10T12:31:36Z" level=error
time="2023-12-10T12:31:36Z" level=error msg="  on storage.tf line 26, in resource \"azurerm_storage_account\" \"cluster\":"
time="2023-12-10T12:31:36Z" level=error msg="  26:       key_vault_key_id          = var.key_vault_key_id"
time="2023-12-10T12:31:36Z" level=error
time="2023-12-10T12:31:36Z" level=error msg="An input variable with the name \"key_vault_key_id\" has not been declared."
time="2023-12-10T12:31:36Z" level=error msg="This variable can be declared with a variable \"key_vault_key_id\" {} block."
time="2023-12-10T12:31:36Z" level=error
time="2023-12-10T12:31:36Z" level=error msg="Error: Invalid reference"
time="2023-12-10T12:31:36Z" level=error
time="2023-12-10T12:31:36Z" level=error msg="  on storage.tf line 27, in resource \"azurerm_storage_account\" \"cluster\":"
time="2023-12-10T12:31:36Z" level=error msg="  27:       user_assigned_identity_id = user_assigned_identity_id"
time="2023-12-10T12:31:36Z" level=error
time="2023-12-10T12:31:36Z" level=error msg="A reference to a resource type must be followed by at least one attribute"
time="2023-12-10T12:31:36Z" level=error msg="access, specifying the resource name."
time="2023-12-10T12:31:36Z" level=error
time="2023-12-10T12:31:36Z" level=error msg="Error: Invalid reference"
time="2023-12-10T12:31:36Z" level=error
time="2023-12-10T12:31:36Z" level=error msg="  on storage.tf line 35, in resource \"azurerm_storage_account\" \"cluster\":"
time="2023-12-10T12:31:36Z" level=error msg="  35:       identity_ids = [user_assigned_identity_id]"
time="2023-12-10T12:31:36Z" level=error
time="2023-12-10T12:31:36Z" level=error msg="A reference to a resource type must be followed by at least one attribute"
time="2023-12-10T12:31:36Z" level=error msg="access, specifying the resource name."
time="2023-12-10T12:31:36Z" level=error msg="failed to fetch Cluster: failed to generate asset \"Cluster\": failed to create cluster: failure applying terraform for \"bootstrap\" stage: error applying Terraform configs: failed to apply Terraform: exit status 1\n\nError: Reference to undeclared input variable\n\n  on storage.tf line 26, in resource \"azurerm_storage_account\" \"cluster\":\n  26:       key_vault_key_id          = var.key_vault_key_id\n\nAn input variable with the name \"key_vault_key_id\" has not been declared.\nThis variable can be declared with a variable \"key_vault_key_id\" {} block.\n\nError: Invalid reference\n\n  on storage.tf line 27, in resource \"azurerm_storage_account\" \"cluster\":\n  27:       user_assigned_identity_id = user_assigned_identity_id\n\nA reference to a resource type must be followed by at least one attribute\naccess, specifying the resource name.\n\nError: Invalid reference\n\n  on storage.tf line 35, in resource \"azurerm_storage_account\" \"cluster\":\n  35:       identity_ids = [user_assigned_identity_id]\n\nA reference to a resource type must be followed by at least one attribute\naccess, specifying the resource name.\n"


seems that issue is introduced by https://github.com/openshift/installer/pull/7642/

4.15.0-0.nightly-2023-12-09-012410    

Always

    1. Configure customerManagedKey for installer storage account in install-config
    2. Continue the installation
    3.
    

    Installer failed 

    Installation is successful

    It works on 4.15.0-0.nightly-2023-12-04-162702