Allow to configure EctoLogger through :telemetry.attach/4

README.md

@@ -6,7 +6,7 @@
 [![Hex pm](http://img.shields.io/hexpm/v/spandex_ecto.svg?style=flat)](https://hex.pm/packages/spandex_ecto)
 [![SourceLevel](https://sourcelevel.io/github/spandex-project/spandex_ecto.svg)](https://sourcelevel.io/github/spandex-project/spandex_ecto)
 
-Tools for integrating Ecto with Spandex
+Tools for integrating Ecto with Spandex.
 
 ## Limitations
 
@@ -30,30 +30,70 @@ end
 
 ## Configuration
 
+Configure `SpandexEcto` globally in your application config:
+
 ```elixir
+# config/config.exs
+
 config :spandex_ecto, SpandexEcto.EctoLogger,
   service: :ecto, # Optional
   tracer: MyApp.Tracer, # Required
 ```
 
-### For Ecto 2
+Then attach it to your repository's telemetry events:
 
 ```elixir
-# Be aware that this is a *compile* time configuration. As such, if you change this you
-# may need to `mix compile --force` and/or `mix deps.compile --force ecto`
-config :my_app, MyApp.Repo,
-  loggers: [{Ecto.LogEntry, :log, [:info]}, {SpandexEcto.EctoLogger, :trace, ["database_name"]}]
+# lib/my_app/application.ex
 
+:ok = :telemetry.attach(
+  "spandex-query-tracer",
+  # this should match your repo's telemetry prefix
+  [:my_app, :repo, :query],
+  &SpandexEcto.TelemetryAdapter.handle_event/4,
+  nil
+)
 ```
 
-### For Ecto 3
+You can override the global configuration by passing overrides to `:telemetry.attach/4` (useful for projects with multiple Ecto repos):
 
 ```elixir
-# in application.ex
-# If your repo is called `MyApp.Repo`, use `[:my_app, :repo, :query]`
-# If your repo is called `Foo.Bar.Baz`, use `[:foo, :bar, :baz, :query]`
-:ok = :telemetry.attach("spandex-query-tracer-repo_name", [:my_app, :repo, :query], &SpandexEcto.TelemetryAdapter.handle_event/4, nil)
+# lib/my_app/application.ex
+
+:ok = :telemetry.attach(
+  "spandex-query-tracer-other-repo",
+  [:my_app, :other_repo, :query],
+  &SpandexEcto.TelemetryAdapter.handle_event/4,
+  # this config will override the global config
+  service: :other_db,
+  tracer: MyApp.OtherRepoTracer
+)
 ```
 
 > NOTE: **If you are upgrading from Ecto 2**, make sure to **remove** the `loggers`
-> entry from your configuration after adding the `:telemetry.attach`.
+> entry from your configuration after adding `:telemetry.attach/4`.
+
+### Options
+
+The following configuration options are supported:
+
+|Option|Description|Default|
+|-|-|-|
+|`tracer`|Tracer instance to use for reporting traces (*required*)||
+|`service`|Service name for Ecto traces|`ecto`|
+|`truncate`|Maximum length of a query (excess will be truncated)|5000|
+
+### Ecto 2
+
+To integrate `SpandexEcto` with pre-`:telemetry` versions of Ecto you need to add `SpandexEcto.EctoLogger` as a logger to your repository.
+
+Be aware that this is a *compile* time configuration. As such, if you change this you may need to `mix compile --force` and/or `mix deps.compile --force ecto`.
+
+```elixir
+# config/config.exs
+
+config :my_app, MyApp.Repo,
+  loggers: [
+    {Ecto.LogEntry, :log, [:info]},
+    {SpandexEcto.EctoLogger, :trace, ["database_name"]}
+  ]
+```

lib/spandex_ecto/ecto_logger.ex

@@ -11,9 +11,13 @@ defmodule SpandexEcto.EctoLogger do
 
   @empty_query_placeholder "unknown (unsupported ecto adapter?)"
 
-  def trace(log_entry, database) do
+  def trace(log_entry, database, config \\ []) do
     # Put in your own configuration here
-    config = Application.get_env(:spandex_ecto, __MODULE__)
+    config =
+      :spandex_ecto
+      |> Application.get_env(__MODULE__)
+      |> Keyword.merge(config || [])
+
     tracer = config[:tracer] || raise "tracer is a required option for #{inspect(__MODULE__)}"
     service = config[:service] || :ecto
     truncate = config[:truncate] || 5000

lib/spandex_ecto/telemetry_adapter.ex

@@ -6,12 +6,12 @@ defmodule SpandexEcto.TelemetryAdapter do
   alias SpandexEcto.EctoLogger
 
   #  this is for ecto_sql 3.0.x
-  def handle_event([_app_name, repo_name, :query], total_time, log_entry, _config) when is_integer(total_time) do
-    EctoLogger.trace(log_entry, "#{repo_name}_database")
+  def handle_event([_app_name, repo_name, :query], total_time, log_entry, config) when is_integer(total_time) do
+    EctoLogger.trace(log_entry, "#{repo_name}_database", config)
   end
 
   # This is for ecto_sql >= 3.1
-  def handle_event([_app_name, repo_name, :query], measurements, metadata, _config) when is_map(measurements) do
+  def handle_event([_app_name, repo_name, :query], measurements, metadata, config) when is_map(measurements) do
     log_entry = %{
       query: metadata.query,
       source: metadata.source,
@@ -22,7 +22,7 @@ defmodule SpandexEcto.TelemetryAdapter do
       result: wrap_result(metadata.result)
     }
 
-    EctoLogger.trace(log_entry, "#{repo_name}_database")
+    EctoLogger.trace(log_entry, "#{repo_name}_database", config)
   end
 
   def handle_event(event_name, measurements, log_entry, config) when is_list(event_name) do