Connect

Overview

Every KubeMQ application starts the same way: open a connection to the broker and prove it actually works before building anything on top of it. This tutorial is that first lesson — start a client process, give it a stable identity, and confirm connectivity with a state check, so the pattern is muscle memory before you move on to real messaging.

KubeMQ.Client.start_link/1 takes an address and a client_id — the ID tags this connection in broker logs, subscriptions, and management views — and starts a supervised GenServer process that opens the gRPC connection. connection_state/1 and connected?/1 verify the connection cheaply, reflecting the process's live state rather than just whether it was created. close/1 shuts the GenServer down and releases the underlying gRPC resources.

Gotchas: {:ok, client} from start_link/1 doesn't always mean the broker is reachable — the GenServer can start before the connection settles, so checking connected?/1 is the only reliable proof; reusing the same client ID across running instances causes routing confusion on the broker; and forgetting to call close/1 in quick scripts is a common source of leaked processes and connections under load.

Prerequisites

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

Code

IO.puts("Connecting to KubeMQ server...")

case KubeMQ.Client.start_link(address: "localhost:50000", client_id: "elixir-connect-example") do
  {:ok, client} ->
    IO.puts("Connected successfully!")
    IO.puts("Connection state: #{KubeMQ.Client.connection_state(client)}")
    IO.puts("Connected? #{KubeMQ.Client.connected?(client)}")
    KubeMQ.Client.close(client)
    IO.puts("Done.")

  {:error, reason} ->
    IO.puts("Connection failed: #{inspect(reason)}")
end

How It Works

• KubeMQ.Client.start_link/1 starts a GenServer and establishes a gRPC connection
• connection_state/1 returns the current connection state atom
• connected?/1 returns a boolean indicating active connectivity
• close/1 gracefully shuts down the GenServer and releases resources

Related

• Elixir SDK Reference
• Close
• Ping