List Channels

Overview

Listing channels turns the broker into a discoverable inventory instead of a black box — instead of hardcoding channel names everywhere, you ask the server what actually exists right now. That's exactly what monitoring dashboards, cleanup scripts, and "did my deployment create the channels it should have" checks need. It's read-only and has no effect on message flow, so it's safe to run against production at any time.

Under the hood, KubeMQ.Client.list_channels/3 queries channels of a given type and returns {:ok, [%ChannelInfo{}]} on success; convenience functions like list_queues_channels/2 wrap the same call with an optional filter string applied server-side. Each ChannelInfo struct carries name, is_active, and incoming/outgoing message counts.

Gotchas: the filter is a prefix/substring match, not a glob or regex — there's no wildcard syntax to anchor or exclude. Every call returns a tagged tuple ({:ok, _} or {:error, _}) rather than raising, so pattern-match on the result instead of wrapping calls in try/rescue. And is_active plus the traffic counters are a snapshot at query time, so a channel can go idle immediately after.

Prerequisites

• KubeMQ server running on localhost:50000
• Elixir SDK installed ({:kubemq, "~> 1.0"} in mix.exs)

Code

{:ok, client} = KubeMQ.Client.start_link(address: "localhost:50000", client_id: "elixir-mgmt-list")

for type <- [:events, :events_store, :commands, :queries, :queues] do
  case KubeMQ.Client.list_channels(client, type) do
    {:ok, channels} ->
      IO.puts("\n#{type} channels (#{length(channels)}):")

      Enum.each(channels, fn ch ->
        IO.puts("  - #{ch.name} (active: #{ch.is_active}, in: #{ch.incoming}, out: #{ch.outgoing})")
      end)

    {:error, err} ->
      IO.puts("\n#{type}: #{err.message}")
  end
end

IO.puts("\n--- Filtered search ---")

case KubeMQ.Client.list_queues_channels(client, "elixir-mgmt") do
  {:ok, channels} ->
    IO.puts("Queue channels matching 'elixir-mgmt': #{length(channels)}")

  {:error, err} ->
    IO.puts("Search failed: #{err.message}")
end

KubeMQ.Client.close(client)

How It Works

• list_channels/3 returns {:ok, [%ChannelInfo{}]} with channel metadata
• Each ChannelInfo includes name, is_active, incoming, and outgoing message counts
• Convenience functions like list_queues_channels/2 accept an optional filter string

Related

• Create Channel
• Delete Channel