rpk: add rpk command to show decommission progress

[daisukebe]

Who is this for and what problem do they have today?

#8167 has added a new endpoint /v1/brokers/<id>/decommission that reports a progress of a node decommissioning (aka partition reconfiguration), example below. We should add a handy rpk sub command that hooks up the endpoint and shows insights for operators.

Example raw output:

daisuke@dev-redpanda/ (dev) $ curl -s http://localhost:9644/v1/brokers/3/decommission | jq .
{
  "finished": false,
  "replicas_left": 3,
  "partitions": [
    {
      "ns": "kafka",
      "topic": "test2",
      "partition": 5,
      "moving_to": {
        "node_id": 3,
        "core": 1
      },
      "bytes_left_to_move": 99992645,
      "bytes_moved": 11796340,
      "partition_size": 111788985
    },
    {
      "ns": "kafka",
      "topic": "test2",
      "partition": 1,
      "moving_to": {
        "node_id": 3,
        "core": 1
      },
      "bytes_left_to_move": 100992922,
      "bytes_moved": 10796433,
      "partition_size": 111789355
    },
    {
      "ns": "kafka",
      "topic": "test2",
      "partition": 7,
      "moving_to": {
        "node_id": 3,
        "core": 1
      },
      "bytes_left_to_move": 100992989,
      "bytes_moved": 11211171,
      "partition_size": 112204160
    }
  ]
}

What are the success criteria?

I'm going to propose a new status command under brokers that reports something like below (just a handwritten example).

$ rpk redpanda brokers decommission-status 3
NAMESPACE-TOPIC PARTITION MOVING_TO PARTITION_SIZE COMPLETION
kafka/test2     7         3         112204160      70%
kafka/test      1         2         111788985      68%

Is the decommission-status sub-command appropriate? @r-vasquez @twmb
@masapanda @JFlath @jason-da-redpanda , I wanted to see how supporters feel. Does the example output above make sense?

Why is solving this problem impactful?

Improving supportability and usability

Additional notes

[r-vasquez]

+1 to decommission-status

I guess it should be next to the decommission command so it will be rpk redpanda admin brokers decommission-status 3

[twmb]

🚲🏠

• Why not --status?
• I'd probably drop NAMESPACE -- do we ever show non-kafka namespace?
• I'd add BYTES-MOVED and BYTES-REMAINING (unless it looks ugly / potentially rename these)

[daisukebe]

Why not --status?

Do you mean something like this, rpk redpanda admin brokers decommission 3 --status? If no option it's making change to the system, but with option it's going to be just fetching the system status. If it's the way to go, I'm fine :)

do we ever show non-kafka namespace?

Yea, under kafka_internal there will be at least tx and id_allocator

I'd add BYTES-MOVED and BYTES-REMAINING (unless it looks ugly / potentially rename these)

+1

[daisukebe]

My 2 cents:
Given the decommission command is a mutation request, I'd suppose it shouldn’t change the basic intention of the command with flags, correct? So that introducing a new status command sounds better to me. Wdyt @twmb @r-vasquez ?

[r-vasquez]

@daisukebe A new command sounds better to me as well.

[daisukebe]

Thank you!