Find Route Tables With A Specific Subnet

Returns all route tables that route to the subnet named subnetname in the virtual network named vnetname. Since the relationship between route tables and subnets is one-to-many, there will only ever be 0 or 1 route tables associated with a given subnet.

policies:
  - name: routes-to-specific-subnet
    resource: azure.routetable
    filters:
      - type: value
        key: properties.subnets[?ends_with(id, 'vnetname/subnets/subnetname')] | [0]
        value: not-null