feat: use iodata for metrics export

This prevents memory bloat form creating all intermediate binaries that
are later dropped. Instead we try to reuse as much of binaries as
possible and then let the VM do the concatenation if needed.

VERSION

@@ -1 +1 @@
-2.1.6
+2.1.7

lib/supavisor/monitoring/prom_ex.ex

@@ -58,7 +58,7 @@ defmodule Supavisor.Monitoring.PromEx do
     end
   end
 
-  @spec get_metrics() :: String.t()
+  @spec get_metrics() :: iodata()
   def get_metrics do
     metrics_tags =
       case Application.fetch_env(:supavisor, :metrics_tags) do
@@ -71,7 +71,7 @@ defmodule Supavisor.Monitoring.PromEx do
     metrics =
       PromEx.get_metrics(__MODULE__)
       |> String.split("\n")
-      |> Enum.map_join("\n", &parse_and_add_tags(&1, def_tags))
+      |> Enum.map(&parse_and_add_tags(&1, def_tags))
 
     Supavisor.Monitoring.PromEx.ETSCronFlusher
     |> PromEx.ETSCronFlusher.defer_ets_flush()
@@ -81,7 +81,7 @@ defmodule Supavisor.Monitoring.PromEx do
 
   @spec do_cache_tenants_metrics() :: list
   def do_cache_tenants_metrics do
-    metrics = get_metrics() |> String.split("\n")
+    metrics = get_metrics() |> IO.iodata_to_binary() |> String.split("\n")
 
     pools =
       Registry.select(Supavisor.Registry.TenantClients, [{{:"$1", :_, :_}, [], [:"$1"]}])
@@ -109,43 +109,21 @@ defmodule Supavisor.Monitoring.PromEx do
     end
   end
 
-  @spec parse_and_add_tags(String.t(), String.t()) :: String.t()
+  @spec parse_and_add_tags(String.t(), String.t()) :: iodata()
   defp parse_and_add_tags(line, def_tags) do
     case Regex.run(~r/(?!\#)^(\w+)(?:{(.*?)})?\s*(.+)$/, line) do
       nil ->
-        line
+        [line, "\n"]
 
       [_, key, tags, value] ->
-        tags = clean_string(tags)
-
         tags =
           if tags == "" do
             def_tags
           else
-            "#{tags},#{def_tags}"
+            [tags, ",", def_tags]
           end
 
-        "#{key}{#{tags}} #{value}"
+        [key, "{", tags, "}", value, "\n"]
     end
   end
-
-  @spec clean_string(String.t()) :: String.t()
-  def clean_string(metric_string) do
-    regex = ~r/=\s*"([^"]*?)"/
-
-    String.replace(metric_string, regex, fn match ->
-      [_, value] = Regex.run(regex, match)
-
-      cleaned =
-        value
-        |> String.replace(~r/\n+/, "")
-        |> String.trim()
-
-      if value != cleaned do
-        Logger.warning("Tag validation: #{inspect(value)} / #{inspect(cleaned)}")
-      end
-
-      "=\"#{cleaned}\""
-    end)
-  end
 end

lib/supavisor_web/controllers/metrics_controller.ex

@@ -56,6 +56,6 @@ defmodule SupavisorWeb.MetricsController do
   end
 
   def merge_node_metrics({_, {_node, metrics}}, acc) do
-    [metrics <> "\n" | acc]
+    [metrics, "\n" | acc]
   end
 end

mix.exs

@@ -52,8 +52,7 @@ defmodule Supavisor.MixProject do
       {:phoenix_live_view, "~> 1.0"},
       {:phoenix_live_dashboard, "~> 0.7"},
       {:telemetry_poller, "~> 1.0"},
-      {:peep, "~> 3.1",
-       github: "hauleth/peep", ref: "94dd35d2c98a858ef20983f2b3da2ab112a07238", override: true},
+      {:peep, "~> 3.4"},
       {:jason, "~> 1.2"},
       {:plug_cowboy, "~> 2.5"},
       {:joken, "~> 2.6.0"},
@@ -83,7 +82,8 @@ defmodule Supavisor.MixProject do
 
       # Test utilities
       {:excoveralls, ">= 0.0.0", only: [:dev, :test]},
-      {:stream_data, "~> 1.0", only: [:dev, :test]}
+      {:stream_data, "~> 1.0", only: [:dev, :test]},
+      {:req, "~> 0.5"}
     ]
   end
 

mix.lock

@@ -44,7 +44,7 @@
   "octo_fetch": {:hex, :octo_fetch, "0.4.0", "074b5ecbc08be10b05b27e9db08bc20a3060142769436242702931c418695b19", [:mix], [{:castore, "~> 0.1 or ~> 1.0", [hex: :castore, repo: "hexpm", optional: false]}, {:ssl_verify_fun, "~> 1.1", [hex: :ssl_verify_fun, repo: "hexpm", optional: false]}], "hexpm", "cf8be6f40cd519d7000bb4e84adcf661c32e59369ca2827c4e20042eda7a7fc6"},
   "open_api_spex": {:hex, :open_api_spex, "3.21.2", "6a704f3777761feeb5657340250d6d7332c545755116ca98f33d4b875777e1e5", [:mix], [{:decimal, "~> 1.0 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: true]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}, {:plug, "~> 1.7", [hex: :plug, repo: "hexpm", optional: false]}, {:poison, "~> 3.0 or ~> 4.0 or ~> 5.0 or ~> 6.0", [hex: :poison, repo: "hexpm", optional: true]}, {:ymlr, "~> 2.0 or ~> 3.0 or ~> 4.0 or ~> 5.0", [hex: :ymlr, repo: "hexpm", optional: true]}], "hexpm", "f42ae6ed668b895ebba3e02773cfb4b41050df26f803f2ef634c72a7687dc387"},
   "opentelemetry_api": {:hex, :opentelemetry_api, "1.4.0", "63ca1742f92f00059298f478048dfb826f4b20d49534493d6919a0db39b6db04", [:mix, :rebar3], [], "hexpm", "3dfbbfaa2c2ed3121c5c483162836c4f9027def469c41578af5ef32589fcfc58"},
-  "peep": {:git, "https://github.com/hauleth/peep.git", "94dd35d2c98a858ef20983f2b3da2ab112a07238", [ref: "94dd35d2c98a858ef20983f2b3da2ab112a07238"]},
+  "peep": {:hex, :peep, "3.4.2", "49d4ca116d994779351959dfee971fb2c7d6506f1821374f3cc4fd39a3d3fadb", [:mix], [{:nimble_options, "~> 1.1", [hex: :nimble_options, repo: "hexpm", optional: false]}, {:plug, "~> 1.16", [hex: :plug, repo: "hexpm", optional: true]}, {:telemetry_metrics, "~> 1.0", [hex: :telemetry_metrics, repo: "hexpm", optional: false]}], "hexpm", "cae224b09e224bf5584f5375108becf71e2288572a099a122e66735289cd33f4"},
   "pg_types": {:hex, :pg_types, "0.4.0", "3ce365c92903c5bb59c0d56382d842c8c610c1b6f165e20c4b652c96fa7e9c14", [:rebar3], [], "hexpm", "b02efa785caececf9702c681c80a9ca12a39f9161a846ce17b01fb20aeeed7eb"},
   "pgo": {:hex, :pgo, "0.14.0", "f53711d103d7565db6fc6061fcf4ff1007ab39892439be1bb02d9f686d7e6663", [:rebar3], [{:backoff, "~> 1.1.6", [hex: :backoff, repo: "hexpm", optional: false]}, {:opentelemetry_api, "~> 1.0", [hex: :opentelemetry_api, repo: "hexpm", optional: false]}, {:pg_types, "~> 0.4.0", [hex: :pg_types, repo: "hexpm", optional: false]}], "hexpm", "71016c22599936e042dc0012ee4589d24c71427d266292f775ebf201d97df9c9"},
   "phoenix": {:hex, :phoenix, "1.7.18", "5310c21443514be44ed93c422e15870aef254cf1b3619e4f91538e7529d2b2e4", [:mix], [{:castore, ">= 0.0.0", [hex: :castore, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}, {:phoenix_pubsub, "~> 2.1", [hex: :phoenix_pubsub, repo: "hexpm", optional: false]}, {:phoenix_template, "~> 1.0", [hex: :phoenix_template, repo: "hexpm", optional: false]}, {:phoenix_view, "~> 2.0", [hex: :phoenix_view, repo: "hexpm", optional: true]}, {:plug, "~> 1.14", [hex: :plug, repo: "hexpm", optional: false]}, {:plug_cowboy, "~> 2.7", [hex: :plug_cowboy, repo: "hexpm", optional: true]}, {:plug_crypto, "~> 1.2 or ~> 2.0", [hex: :plug_crypto, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}, {:websock_adapter, "~> 0.5.3", [hex: :websock_adapter, repo: "hexpm", optional: false]}], "hexpm", "1797fcc82108442a66f2c77a643a62980f342bfeb63d6c9a515ab8294870004e"},

test/supavisor/monitoring/prom_ex_test.exs

@@ -0,0 +1,126 @@
+defmodule Supavisor.Monitoring.PromExTest do
+  use Supavisor.DataCase, async: true
+  use ExUnitProperties
+
+  @subject Supavisor.Monitoring.PromEx
+
+  @tenant "prom_tenant"
+
+  setup do
+    db_conf = Application.get_env(:supavisor, Repo)
+
+    {:ok, proxy} =
+      Postgrex.start_link(
+        hostname: db_conf[:hostname],
+        port: Application.get_env(:supavisor, :proxy_port_transaction),
+        database: db_conf[:database],
+        password: db_conf[:password],
+        username: db_conf[:username] <> "." <> @tenant,
+        socket_dir: nil,
+        show_sensitive_data_on_connection_error: true
+      )
+
+    assert :idle == DBConnection.status(proxy)
+
+    %{proxy: proxy, user: db_conf[:username], db_name: db_conf[:database]}
+  end
+
+  describe "get_metrics/1" do
+    @sources %{
+      {:darwin, :aarch64} => {
+        "https://github.com/prometheus/prom2json/releases/download/v1.4.1/prom2json-1.4.1.darwin-arm64.tar.gz",
+        "prom2json-1.4.1.darwin-arm64/prom2json"
+      }
+    }
+    setup do
+      {:ok, prom2json: Supavisor.Downloader.ensure("prom2json", @sources)}
+    end
+
+    @tag :tmp_dir
+    test "returned metrics are parseable", %{tmp_dir: dir, prom2json: exe} do
+      metrics = @subject.get_metrics()
+      file = Path.join(dir, "prom.out")
+      File.write!(file, metrics)
+
+      assert {_, 0} = System.cmd(exe, [file])
+    end
+
+    @tag :tmp_dir
+    property "non-standard DB names do not cause parsing issues", %{tmp_dir: dir, prom2json: exe} do
+      tenant = "tenant"
+      user = "user"
+
+      check all db_name <- string(:printable, min_length: 1, max_length: 63) do
+        Supavisor.Monitoring.Telem.client_join(
+          :ok,
+          {{:single, tenant}, user, :session, db_name, nil}
+        )
+
+        metrics = @subject.get_metrics()
+        file = Path.join(dir, "prom.out")
+        File.write!(file, metrics)
+
+        assert {out, 0} = System.cmd(exe, [file])
+        assert {:ok, measurements} = Jason.decode(out)
+
+        assert %{"metrics" => metrics} =
+                 Enum.find(measurements, &(&1["name"] == "supavisor_client_joins_ok"))
+
+        assert Enum.find(metrics, &(&1["labels"]["db_name"] == db_name))
+      end
+    end
+
+    @tag :tmp_dir
+    property "non-standard user names do not cause parsing issues", %{
+      tmp_dir: dir,
+      prom2json: exe
+    } do
+      tenant = "tenant"
+      db_name = "db_name"
+
+      check all user <- string(:printable, min_length: 1, max_length: 63) do
+        Supavisor.Monitoring.Telem.client_join(
+          :ok,
+          {{:single, tenant}, user, :session, db_name, nil}
+        )
+
+        metrics = @subject.get_metrics()
+        file = Path.join(dir, "prom.out")
+        File.write!(file, metrics)
+
+        assert {out, 0} = System.cmd(exe, [file])
+        assert {:ok, measurements} = Jason.decode(out)
+
+        assert %{"metrics" => metrics} =
+                 Enum.find(measurements, &(&1["name"] == "supavisor_client_joins_ok"))
+
+        assert Enum.find(metrics, &(&1["labels"]["db_name"] == db_name))
+      end
+    end
+
+    @tag :tmp_dir
+    property "non-standard tenant names do not cause parsing issues", %{tmp_dir: dir} do
+      db_name = "db_name"
+      user = "user"
+
+      check all tenant <- string(:printable, min_length: 1) do
+        Supavisor.Monitoring.Telem.client_join(
+          :ok,
+          {{:single, tenant}, user, :session, db_name, nil}
+        )
+
+        metrics = @subject.get_metrics()
+        file = Path.join(dir, "prom.out")
+        File.write!(file, metrics)
+
+        assert {out, 0} = System.cmd("prom2json", [file])
+        assert {:ok, measurements} = Jason.decode(out)
+
+        assert %{"metrics" => metrics} =
+                 Enum.find(measurements, &(&1["name"] == "supavisor_client_joins_ok"))
+
+        assert Enum.find(metrics, &(&1["labels"]["db_name"] == db_name))
+      end
+    end
+  end
+end

test/support/downloader.ex

@@ -0,0 +1,53 @@
+defmodule Supavisor.Downloader do
+  def ensure(name, sources) do
+    case System.find_executable(name) do
+      nil -> do_download(name, sources)
+      path -> path
+    end
+  end
+
+  def do_download(name, sources) do
+    path = System.tmp_dir!()
+    arch = os_arch()
+
+    source =
+      case Map.fetch(sources, arch) do
+        {:ok, src} -> src
+        :error -> raise "Cannot find source for #{inspect(arch)}"
+      end
+
+    {url, file} =
+      case source do
+        {url, file} -> {url, file}
+        url when is_binary(url) -> {url, name}
+      end
+
+    out = Path.join(path, file)
+
+    if not File.exists?(out) do
+      %Req.Response{status: 200, body: body} = Req.get!(url)
+
+      :ok =
+        :erl_tar.extract({:binary, body}, [
+          :compressed,
+          cwd: to_charlist(path),
+          files: [to_charlist(file)]
+        ])
+    end
+
+    out
+  end
+
+  defp os_arch do
+    {_, name} = :os.type()
+
+    arch =
+      :erlang.system_info(:system_architecture)
+      |> List.to_string()
+      |> String.split("-", parts: 2)
+      |> hd()
+      |> String.to_atom()
+
+    {name, arch}
+  end
+end