cli: Add JSON and Pretty Print formatting for consul snapshot inspect

[schristoff]

Previous functionality still available unchanged:

consul snapshot inspect backup.snap
 ID           2-13-1603221729747
 Size         5141
 Index        13
 Term         2
 Version      1

 Type                        Count      Size
 ----                        ----       ----
 Register                    3          1.7KB
 ConnectCA                   1          1.2KB
 ConnectCAProviderState      1          1.1KB
 Index                       12         344B
 Autopilot                   1          199B
 ConnectCAConfig             1          197B
 FederationState             1          139B
 SystemMetadata              1          68B
 ChunkingState               1          12B
 ----                        ----       ----
 Total                                  5KB

However the addition of JSON output with specified flag is available:

$ consul snapshot inspect -format=json backup.snap
{
   "Meta": {
      "ID": "2-13-1603221729747",
      "Size": 5141,
      "Index": 13,
      "Term": 2,
      "Version": 1
   },
   "Stats": {
      "0": {
         "Name": "Register",
         "Sum": 1750,
         "Count": 3
      },
      "13": {
         "Name": "ConnectCA",
         "Sum": 1258,
         "Count": 1
      },
      "14": {
         "Name": "ConnectCAProviderState",
         "Sum": 1174,
         "Count": 1
      },
      "15": {
         "Name": "ConnectCAConfig",
         "Sum": 197,
         "Count": 1
      },
      "16": {
         "Name": "Index",
         "Sum": 344,
         "Count": 12
      },
      "29": {
         "Name": "ChunkingState",
         "Sum": 12,
         "Count": 1
      },
      "30": {
         "Name": "FederationState",
         "Sum": 139,
         "Count": 1
      },
      "31": {
         "Name": "SystemMetadata",
         "Sum": 68,
         "Count": 1
      },
      "9": {
         "Name": "Autopilot",
         "Sum": 199,
         "Count": 1
      }
   },
   "Offset": 5141
}

[mkeeler]

The code looks great. I just have the one question about the JSON formats structure.

[mkeeler]

I wonder whether this field should be Stats []typeStats. In the pretty output I see that you are creating a slice of these and then sorting. For the JSON output I wonder whether it would be better to see:

"Stats": [
   {
      "Name": "Register",
      "Count": 20,
      "Sum": 1537,
   }
]

Having the MessageType (int) as a map key in JSON doesn't seem that useful. Also having it in an array would more easily allow us to aggregate stats for namespaces without having the map keys conflict.

[schristoff]

Oh I didn't even notice that, good catch.

[mkeeler]