How to use Cribl Aggregate function

Question

I'm using Cribl Stream version 4.2.2 and don't understand how to use the Aggregate function to group data by a unique key.

I get the below data sets streamed into Cribl:

{
  "fields": {
    "a_node": "device1",
    "carrier_transitions": 1,
    "description": "Device description",
    "out_bps": 0,
    "out_broadcast_pkts": 123,
    "out_multicast_pkts": 222,
    "out_octets": 333,
    "out_pkts": 111
  },
  "name": "interfaces",
  "tags": {
    "device": "device1.mgt.net",
    "interface_name": "et-2/3/3",
  },
  "timestamp": 1710777509
}

{
  "fields": {
    "in_bps": 0,
    "in_broadcast_pkts": 36,
    "in_multicast_pkts": 123,
    "in_octets": 12,
    "in_pkts": 123,
    "in_unicast_pkts": 122
  },
  "name": "interfaces",
  "tags": {
    "device": "device1.mgt.net",
    "interface_name": "et-2/3/3",
  },
  "timestamp": 1710777509
}

I want to aggregate them based on device and inteface_name so that I can get a resulting data set that looks like this:

{
  "fields": {
    "a_node": "device1",
    "carrier_transitions": 1,
    "description": "Device description",
    "out_bps": 0,
    "out_broadcast_pkts": 123,
    "out_multicast_pkts": 222,
    "out_octets": 333,
    "out_pkts": 111,
    "in_bps": 0,
    "in_broadcast_pkts": 36,
    "in_multicast_pkts": 123,
    "in_octets": 12,
    "in_pkts": 123,
    "in_unicast_pkts": 122
  },
  "name": "interfaces",
  "tags": {
    "device": "device1.mgt.net",
    "interface_name": "et-2/3/3",
  },
  "timestamp": 1710777509
}