azure-vmss-empty-unattached: Azure Virtual Machine Scale Sets Empty and Unattached

id: azure-vmss-empty-unattached
info:
  name: Azure Virtual Machine Scale Sets Empty and Unattached
  author: princechaddha
  severity: low
  description: |
    Identify any empty virtual machine scale sets available within your Microsoft Azure cloud account and delete them in order to eliminate unnecessary costs and meet compliance requirements when it comes to unused resources. A Microsoft Azure virtual machine scale set is considered empty when it doesn't have any VM instances attached anymore and is no longer associated with a load balancer.
  impact: |
    Maintaining empty VM scale sets can incur unnecessary costs and occupy valuable resources that could be utilized elsewhere.
  remediation: |
    Regularly check and remove any VM scale sets that do not contain any VM instances and are not associated with any load balancers.
  reference:
    - https://docs.microsoft.com/en-us/azure/virtual-machine-scale-sets/
  tags: cloud,devops,azure,microsoft,vmss,azure-cloud-config

flow: |
  code(1);
  for (let ScaleSetData of iterate(template.scaleSetList)) {
    ScaleSetData = JSON.parse(ScaleSetData);
    set("name", ScaleSetData.Name);
    set("resourceGroup", ScaleSetData.ResourceGroup);
    code(2);
  }

self-contained: true
code:
  - engine:
      - sh
      - bash
    source: |
      az vmss list --output json --query '[*].{"Name":name,"ResourceGroup":resourceGroup}'

    extractors:
      - type: json
        name: scaleSetList
        internal: true
        json:
          - '.[]'

  - engine:
      - sh
      - bash
    source: |
      az vmss list-instances --name "$name" --resource-group "$resourceGroup" --query '[*].id'

    matchers-condition: and
    matchers:
      - type: word
        words:
          - '[]'

    extractors:
      - type: dsl
        dsl:
          - 'name + " in " + resourceGroup + " is empty and unattached"'
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