lib/ha_handler.ex

@@ -13,7 +13,6 @@ defmodule HAHandler do
   def haproxy_socket, do: Application.get_env(@otp_app, :haproxy_socket)
   def pgsql_instances, do: Application.get_env(@otp_app, :pgsql_instances, [])
   def drbd_instances, do: Application.get_env(@otp_app, :drbd_instances, [])
-  def handler_instances, do: Application.get_env(@otp_app, :handler_instances, [])
 
   def acme_challenge_path, do: Application.get_env(@otp_app, :acme_challenge_path)
   def static_path(), do: Application.app_dir(@otp_app, "priv/static/")

lib/ha_handler/application.ex

@@ -14,7 +14,6 @@ defmodule HAHandler.Application do
        scheme: :http, plug: HAHandler.Web.Router, options: [port: HAHandler.http_port()]},
       {HAHandler.PGSQL.Supervisor, HAHandler.pgsql_instances()},
       {HAHandler.DRBD.Supervisor, HAHandler.drbd_instances()},
-      {HAHandler.Cluster, HAHandler.handler_instances()},
       {HAHandler.Control, []}
     ]
 

lib/ha_handler/cluster.ex

@@ -1,108 +0,0 @@
-defmodule HAHandler.Cluster do
-  use GenServer
-  require Logger
-
-  # How much do we wait (ms) between each check/decision-making round?
-  @refresh 30_000
-
-  def start_link(opts) do
-    GenServer.start_link(__MODULE__, opts, name: __MODULE__)
-  end
-
-  @impl true
-  def init(instances) do
-    if Node.alive?() do
-      Logger.info("Distribution/clustering is ENABLED.")
-      Logger.info("Current handler instance is: #{Node.self()}")
-      Logger.info("Configured handler instances: #{inspect(instances)}")
-      :net_kernel.monitor_nodes(true)
-
-      send(self(), :sync)
-    else
-      Logger.warning("Distribution is DISABLED - skipping clustering logic")
-    end
-
-    {:ok, instances}
-  end
-
-  @impl true
-  def handle_info(:sync, instances) do
-    current_network = Node.list() ++ [Node.self()]
-
-    for node_name <- instances do
-      # Nothing to do if the node is already in our network/cluster.
-      if node_name not in current_network do
-        case Node.connect(node_name) do
-          true ->
-            Logger.info("Connected to handler instance #{node_name}")
-          _ ->
-            Logger.warning("Could not connect to handler instance #{node_name}")
-        end
-      end
-    end
-
-    Process.send_after(self(), :sync, @refresh)
-
-    {:noreply, instances}
-  end
-
-  @impl true
-  def handle_info({:nodedown, node}, instances) do
-    Logger.warning("Node #{node} went down.")
-
-    {:noreply, instances}
-  end
-
-  @impl true
-  def handle_info({:nodeup, node}, instances) do
-    Logger.info("Node #{node} came up.")
-
-    send(self(), :sync)
-
-    {:noreply, instances}
-  end
-
-  @impl true
-  def handle_call(:get_details, _from, instances) do
-    {uptime_ms, _} = :erlang.statistics(:wall_clock)
-
-    local_details = %{
-      node: Node.self(),
-      otp_app: HAHandler.otp_app,
-      version: HAHandler.version,
-      uptime: round(uptime_ms / 1_000 / 60),
-      env: HAHandler.env
-    }
-
-    {:reply, local_details, instances}
-  end
-
-  @impl true
-  def handle_call(:get_instances, _from, instances) do
-    {:reply, instances, instances}
-  end
-
-  def get_instance_details() do
-    known_instances = [Node.self()] ++ Node.list() ++ GenServer.call(__MODULE__, :get_instances)
-
-    known_instances
-    |> Enum.uniq()
-    |> Enum.map(fn node ->
-      try do
-        # FIXME: remote node coud return garbage/another structure!
-        GenServer.call({__MODULE__, node}, :get_details)
-        |> Map.put(:status, :up)
-      catch
-        :exit, _err ->
-          %{
-            node: node,
-            otp_app: :unknown,
-            version: :unknown,
-            uptime: :unknown,
-            env: :unknown,
-            status: :down
-          }
-      end
-    end)
-  end
-end

lib/ha_handler/control.ex

@@ -173,13 +173,8 @@ defmodule HAHandler.Control do
   def handle_info(:sync, state) do
     Logger.debug("Executing control logic.")
 
-    case HAProxy.get_stats() do
-      %{} ->
-        process_pgsql()
-        process_drbd()
-      {:error, err} ->
-        Logger.error("Unable to fetch HAProxy state (#{inspect(err)}) - skipping control loop.")
-    end
+    process_pgsql()
+    process_drbd()
 
     # Schedule next round.
     Process.send_after(self(), :sync, @refresh)

lib/ha_handler/web/controller.ex

@@ -1,7 +1,7 @@
 defmodule HAHandler.Web.Controller do
   import Plug.Conn
 
-  alias HAHandler.{HAProxy, PGSQL, DRBD, Cluster}
+  alias HAHandler.{HAProxy, PGSQL, DRBD}
 
   @template_dir "lib/ha_handler/web/templates"
   @index_template EEx.compile_file(Path.join(@template_dir, "index.html.eex"))
@@ -20,13 +20,11 @@ defmodule HAHandler.Web.Controller do
     haproxy_stats = HAProxy.get_stats(hide_error: true)
     pgsql_stats = PGSQL.get_stats()
     drbd_stats = DRBD.get_stats()
-    handler_stats = Cluster.get_instance_details()
 
     assigns = [
       haproxy_stats: haproxy_stats,
       pgsql_status: pgsql_stats,
       drbd_status: drbd_stats,
-      handler_status: handler_stats,
       hostname: hostname,
       otp_app: HAHandler.otp_app(),
       version: HAHandler.version(),

lib/ha_handler/web/templates/index.html.eex

@@ -25,32 +25,7 @@
 
       <h2>Handler</h2>
 
-      <p>
-        <b>Local instance:</b> <%= otp_app %> <b>v<%= version %></b> (<%= env %>) running on <b><%= hostname %></b>
-      </p>
-
-      <table>
-        <thead>
-          <tr>
-            <th>Instance</th>
-            <th>Version</th>
-            <th>Env</th>
-            <th>Status</th>
-            <th>Uptime</th>
-          </tr>
-        </thead>
-        <tbody>
-          <%= for instance <- handler_status do %>
-            <tr>
-              <td><%= instance.node %></td>
-              <td><%= instance.version %></td>
-              <td><%= instance.env %></td>
-              <td><%= instance.status %></td>
-              <td><%= instance.uptime %>m</td>
-            </tr>
-          <% end %>
-        </tbody>
-      </table>
+      <%= otp_app %> <b>v<%= version %></b> (<%= env %>) running on <b><%= hostname %></b>
 
       <hr />
 

mix.exs

@@ -4,7 +4,7 @@ defmodule HAHandler.MixProject do
   def project do
     [
       app: :ha_handler,
-      version: "0.4.0",
+      version: "0.3.0",
       elixir: "~> 1.12",
       start_permanent: Mix.env() == :prod,
       deps: deps(),