curl --request GET \
  --url https://drb.coinbase.com/api/v2/public/get_order_book \
  --header 'Content-Type: application/json' \
  --data '
{
  "id": 8772,
  "jsonrpc": "2.0",
  "method": "public/get_order_book",
  "params": {
    "depth": 5,
    "instrument_name": "BTC-PERPETUAL"
  }
}
'

{
  "id": 8772,
  "jsonrpc": "2.0",
  "result": {
    "asks": [],
    "best_ask_amount": 0,
    "best_ask_price": 0,
    "best_bid_amount": 30,
    "best_bid_price": 3955.75,
    "bids": [
      [
        3955.75,
        30
      ],
      [
        3940.75,
        102020
      ],
      [
        3423,
        42840
      ]
    ],
    "change_id": 474988,
    "current_funding": 0.00500063,
    "funding_8h": 0.00455263,
    "index_price": 3910.46,
    "instrument_name": "BTC-PERPETUAL",
    "last_price": 3955.75,
    "mark_price": 3931.97,
    "max_price": 3971.74,
    "min_price": 3932.22,
    "open_interest": 45.27600333464605,
    "settlement_price": 3925.85,
    "state": "open",
    "stats": {
      "high": 3976.25,
      "low": 3940.75,
      "price_change": 0.6913,
      "volume": 93.35589552
    },
    "timestamp": 1550757626706
  }
}