Add automatic scrubber

lib/archive/schemas/page_view.ex

@@ -16,7 +16,7 @@ defmodule Tilastokeskus.Archive.Schemas.PageView do
     # Request path without query string
     field(:path_noq, :string)
 
-    # Request host header
+    # Request URL host (authority)
     field(:host, :string)
 
     # Full HTTP referrer

lib/archive/scrubinator.ex

+defmodule Tilastokeskus.Archive.Scrubinator do
+  @moduledoc """
+  Scrubinator is a timed assassin that periodically scrubs log data from too sensitive
+  information.
+  """
+
+  @how_often 24 * 60 * 60 * 1000
+
+  use GenServer
+  alias Tilastokeskus.Archive.Schemas.PageView
+  alias Tilastokeskus.Archive.Repo
+  import Ecto.Query, only: [from: 2]
+
+  def start_link(opts) do
+    GenServer.start_link(__MODULE__, opts)
+  end
+
+  def init(%{days: days} = state) do
+    :ok = scrub(days)
+
+    Process.send_after(self(), :scrub, @how_often)
+    {:ok, state}
+  end
+
+  def handle_info(:scrub, %{days: days} = state) do
+    :ok = scrub(days)
+
+    Process.send_after(self(), :scrub, @how_often)
+    {:noreply, state}
+  end
+
+  @doc """
+  Scrub hits older than `days` days of private data.
+  """
+  @spec scrub(integer) :: :ok
+  def scrub(days) do
+    now = DateTime.utc_now() |> DateTime.to_unix()
+    then = now - days * 24 * 60 * 60
+
+    case DateTime.from_unix(then) do
+      {:ok, then_dt} ->
+        from(
+          p in PageView,
+          where: p.at <= ^then_dt and p.scrubbed == false,
+          update: [
+            set: [
+              scrubbed: true,
+              addr: nil,
+              ua: nil,
+              loc_city: nil
+            ]
+          ]
+        )
+        |> Repo.update_all([])
+
+        :ok
+
+      {:error, _} ->
+        :ok
+    end
+  end
+end

lib/tilastokeskus/application.ex

@@ -10,10 +10,12 @@ defmodule Tilastokeskus.Application do
 
     port = (System.get_env("PORT") || "1971") |> String.to_integer()
     hosts = get_hosts()
+    days = get_days()
 
     # List all child processes to be supervised
     children = [
       {Tilastokeskus.Archive.Repo, []},
+      {Tilastokeskus.Archive.Scrubinator, %{days: days}},
       {Tilastokeskus.Reception.Router, [[hosts: hosts], [port: port]]}
     ]
 
@@ -29,4 +31,11 @@ defmodule Tilastokeskus.Application do
       hosts -> String.split(hosts, ",")
     end
   end
+
+  defp get_days() do
+    case System.get_env("TILASTOKESKUS_SCRUB_DAYS") do
+      nil -> 90
+      days -> String.to_integer(days)
+    end
+  end
 end