ryan
9d8306a64b
- MQTT client with configurable broker connection - Periodic system stats publishing (30s interval) - Command listening on MQTT topic with logging - Systemd service configuration - NixOS module for declarative deployment 🤖 Generated with [Claude Code](https://claude.ai/code) Co-Authored-By: Claude <noreply@anthropic.com>
92 lines
2.7 KiB
Elixir
92 lines
2.7 KiB
Elixir
defmodule SystemStatsDaemon.MqttClient do
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use GenServer
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require Logger
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@moduledoc """
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MQTT client for publishing system stats and handling commands
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"""
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def start_link(opts) do
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GenServer.start_link(__MODULE__, opts, name: __MODULE__)
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end
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def init(_opts) do
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config = Application.get_env(:system_stats_daemon, __MODULE__)
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Logger.info("Starting MQTT client with config: #{inspect(config)}")
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# Use a unique client ID to avoid conflicts
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client_id = "#{config[:client_id]}_#{:rand.uniform(1000)}"
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connection_opts = [
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client_id: client_id,
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server: {Tortoise.Transport.Tcp, host: to_charlist(config[:host]), port: config[:port]},
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handler: {Tortoise.Handler.Logger, []},
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user_name: config[:username],
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password: config[:password],
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subscriptions: [{config[:command_topic], 0}]
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]
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case Tortoise.Connection.start_link(connection_opts) do
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{:ok, _pid} ->
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Logger.info("MQTT client connected successfully")
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# Send immediate hello message
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hello_msg = %{
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message: "Hello - system_stats_daemon started",
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timestamp: DateTime.utc_now() |> DateTime.to_iso8601(),
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hostname: get_hostname()
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}
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Tortoise.publish(client_id, config[:stats_topic], Jason.encode!(hello_msg), qos: 0)
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schedule_stats_publish(config[:publish_interval])
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{:ok, %{config: config, client_id: client_id}}
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{:error, reason} ->
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Logger.error("Failed to connect to MQTT broker: #{inspect(reason)}")
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{:stop, reason}
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end
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end
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def handle_info(:publish_stats, state) do
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publish_stats(state.config, state.client_id)
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schedule_stats_publish(state.config[:publish_interval])
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{:noreply, state}
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end
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def handle_info(_msg, state) do
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{:noreply, state}
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end
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def terminate(reason, state) do
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Logger.info("MQTT client terminating: #{inspect(reason)}")
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:ok
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end
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defp publish_stats(config, client_id) do
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stats = %{
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message: "Hello from system_stats_daemon",
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timestamp: DateTime.utc_now() |> DateTime.to_iso8601(),
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hostname: get_hostname()
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}
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payload = Jason.encode!(stats)
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case Tortoise.publish(client_id, config[:stats_topic], payload, qos: 0) do
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:ok ->
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Logger.info("Published stats: #{payload}")
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{:error, reason} ->
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Logger.error("Failed to publish stats: #{inspect(reason)}")
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end
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end
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defp schedule_stats_publish(interval) do
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Process.send_after(self(), :publish_stats, interval)
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end
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defp get_hostname do
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case :inet.gethostname() do
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{:ok, hostname} -> List.to_string(hostname)
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_ -> "unknown"
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end
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end
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end |