Retrieve existing clusters

Example response

[
  {
    "name": "cluster0",
    "dse_version": "5.0.8",
    "data_centers": [
      {
        "name": "dc0",
        "nodes": [
          {
            "name": "node0",
            "peer_info": {
              "rack": "rack0"
            }
          },
          {
            "name": "node1",
            "peer_info": {
              "rack": "rack1"
            }
          },
          {
            "name": "node2",
            "peer_info": {
              "rack": "rack2"
            }
          }
        ]
      },
      {
        "name": "dc1",
        "nodes": [
          {
            "name": "node0"
          },
          {
            "name": "node1"
          }
        ]
      }
    ]
  }
]