Be sure to add the following to finish setting up PromEx:

1. Update your configuration (config.exs, dev.exs, prod.exs, releases.exs, etc) to configure the necessary bit of PromEx. Be sure to check out PromEx.Config for more details regarding configuring PromEx:

   config :lightning, Lightning.PromEx,
     disabled: false,
     manual_metrics_start_delay: :no_delay,
     drop_metrics_groups: [],
     grafana: :disabled,
     metrics_server: :disabled

2. Add this module to your application supervision tree. It should be one of the first things that is started so that no Telemetry events are missed. For example, if PromEx is started after your Repo module, you will miss Ecto's init events and the dashboards will be missing some data points:

   def start(_type, _args) do
     children = [
       Lightning.PromEx,
   
       ...
     ]
   
     ...
   end

3. Update your endpoint.ex file to expose your metrics (or configure a standalone server using the :metrics_server config options). Be sure to put this plug before your Plug.Telemetry entry so that you can avoid having calls to your /metrics endpoint create their own metrics and logs which can pollute your logs/metrics given that Prometheus will scrape at a regular interval and that can get noisy:

   defmodule LightningWeb.Endpoint do
     use Phoenix.Endpoint, otp_app: :lightning
   
     ...
   
     plug PromEx.Plug, prom_ex_module: Lightning.PromEx
   
     ...
   end

4. Update the list of plugins in the plugins/0 function return list to reflect your application's dependencies. Also update the list of dashboards that are to be uploaded to Grafana in the dashboards/0 function.