Set up telemetry and prometheus

lib/pleroma/application.ex

@@ -25,6 +25,7 @@ defmodule Pleroma.Application do
     import Cachex.Spec
 
     Pleroma.Config.DeprecationWarnings.warn()
+    setup_instrumenters()
 
     # Define workers and child supervisors to be supervised
     children =
@@ -140,6 +141,13 @@ defmodule Pleroma.Application do
       end
   end
 
+  defp setup_instrumenters() do
+    Pleroma.Web.Endpoint.MetricsExporter.setup()
+    Pleroma.Web.Endpoint.PipelineInstrumenter.setup()
+    Pleroma.Web.Endpoint.Instrumenter.setup()
+    Pleroma.Repo.Instrumenter.setup()
+  end
+
   if Mix.env() == :test do
     defp streamer_child, do: []
     defp chat_child, do: []

lib/pleroma/repo.ex

@@ -8,6 +8,10 @@ defmodule Pleroma.Repo do
     adapter: Ecto.Adapters.Postgres,
     migration_timestamps: [type: :naive_datetime_usec]
 
+  defmodule Instrumenter do
+    use Prometheus.EctoInstrumenter
+  end
+
   @doc """
   Dynamically loads the repository url from the
   DATABASE_URL environment variable.

lib/pleroma/web/endpoint.ex

@@ -70,6 +70,26 @@ defmodule Pleroma.Web.Endpoint do
     extra: "SameSite=Strict"
   )
 
+  # Note: the plug and its configuration is compile-time this can't be upstreamed yet
+  if proxies = Pleroma.Config.get([__MODULE__, :reverse_proxies]) do
+    plug(RemoteIp, proxies: proxies)
+  end
+
+  defmodule Instrumenter do
+    use Prometheus.PhoenixInstrumenter
+  end
+
+  defmodule PipelineInstrumenter do
+    use Prometheus.PlugPipelineInstrumenter
+  end
+
+  defmodule MetricsExporter do
+    use Prometheus.PlugExporter
+  end
+
+  plug(PipelineInstrumenter)
+  plug(MetricsExporter)
+
   plug(Pleroma.Web.Router)
 
   @doc """