Json file, replace “/subscriptions/11111111-1111-1111-1111-111111111111” with your own subscription ID.

Save the Json file and run: az role definition create –role-definition filename.json

 {
      "Name": "Virtual Machine Stop/Start/Restart",
      "IsCustom": true,
      "Description": "Can stop, start  and restart virtual machines.",
      "Actions": [
        "Microsoft.Compute/*/read",
        "Microsoft.Compute/virtualMachines/start/action",
        "Microsoft.Compute/virtualMachines/restart/action",
        "Microsoft.Compute/virtualMachines/deallocate/action"
      ],
      "NotActions": [


      ],
      "AssignableScopes": [
        "/subscriptions/11111111-1111-1111-1111-111111111111"
      ]
    }