Use cache for storing monitors

lib/uplink/application.ex

@@ -22,7 +22,6 @@ defmodule Uplink.Application do
       {Cluster.Supervisor, [topologies, [name: Uplink.ClusterSupervisor]]},
       {Task.Supervisor, name: Uplink.TaskSupervisor},
       {Plug.Cowboy, plug: Uplink.Internal, scheme: :http, port: internal_port},
-      {Uplink.Pipelines.Context, [name: :metrics, monitors: []]},
       {Pogo.DynamicSupervisor,
        [name: Uplink.PipelineSupervisor, scope: :uplink]},
       {Uplink.Monitors, []},

lib/uplink/monitors.ex

@@ -1,6 +1,7 @@
 defmodule Uplink.Monitors do
   use Task
 
+  alias Uplink.Cache
   alias Uplink.Pipelines
   alias Uplink.Clients.Instellar
 
@@ -15,10 +16,14 @@ defmodule Uplink.Monitors do
   end
 
   def run(_options) do
+    Cache.put_new({:monitors, :metrics}, [])
+
     Instellar.list_monitors()
     |> case do
       {:ok, monitors} ->
-        start_pipeline(monitors, :metrics)
+        Cache.transaction([keys: [{:monitors, :metrics}]], fn ->
+          start_pipeline(monitors, :metrics)
+        end)
 
       error ->
         {:error, error}

lib/uplink/pipelines.ex

@@ -1,11 +1,15 @@
 defmodule Uplink.Pipelines do
-  defdelegate get_monitors(context),
-    to: __MODULE__.Context,
-    as: :get
+  alias Uplink.Cache
 
-  defdelegate append_monitors(context, monitors),
-    to: __MODULE__.Context,
-    as: :append
+  def get_monitors(context) do
+    Cache.get({:monitors, context}) || []
+  end
+
+  def append_monitors(context, monitors) do
+    Cache.get_and_update({:monitors, context}, fn existing_monitors ->
+      {existing_monitors, existing_monitors ++ monitors}
+    end)
+  end
 
   def start(module) do
     spec = %{