Report Redix error messages through OTel status (#81)

Instead of custom attributes, leverage the status description as
described in Semantic Conventions. This approach is taken from current
`opentelemetry_ecto` implementation.

Small non-related change is a fix the license description in `mix.exs`.

instrumentation/opentelemetry_redix/CHANGELOG.md

@@ -1,5 +1,12 @@
 # Changelog
 
+## 0.1.1
+
+### Bug fixes
+
+* Report errors via OpenTelemetry SetStatus API instead of custom
+  attributes
+
 ## 0.1.0
 
 * Initial release

instrumentation/opentelemetry_redix/lib/opentelemetry_redix.ex

@@ -60,7 +60,6 @@ defmodule OpentelemetryRedix do
       }
       |> Map.merge(net_attributes(connection))
       |> Map.merge(redix_attributes(meta))
-      |> Map.merge(error_attributes(meta))
 
     s =
       OpenTelemetry.Tracer.start_span(operation, %{
@@ -69,8 +68,8 @@ defmodule OpentelemetryRedix do
         attributes: attributes
       })
 
-    if meta[:reason] do
-      OpenTelemetry.Span.set_status(s, OpenTelemetry.status(:error, ""))
+    if meta[:kind] == :error do
+      OpenTelemetry.Span.set_status(s, OpenTelemetry.status(:error, format_error(meta.reason)))
     end
 
     OpenTelemetry.Span.end_span(s)
@@ -87,6 +86,6 @@ defmodule OpentelemetryRedix do
   defp redix_attributes(%{connection_name: name}), do: %{"db.redix.connection_name": name}
   defp redix_attributes(_), do: %{}
 
-  defp error_attributes(%{reason: reason}), do: %{"db.redix.error": inspect(reason)}
-  defp error_attributes(_), do: %{}
+  defp format_error(%{__exception__: true} = exception), do: Exception.message(exception)
+  defp format_error(reason), do: inspect(reason)
 end

instrumentation/opentelemetry_redix/mix.exs

@@ -5,7 +5,7 @@ defmodule OpentelemetryRedix.MixProject do
     [
       app: :opentelemetry_redix,
       description: description(),
-      version: "0.1.0",
+      version: "0.1.1",
       elixir: "~> 1.10",
       start_permanent: Mix.env() == :prod,
       deps: deps(),
@@ -23,7 +23,7 @@ defmodule OpentelemetryRedix.MixProject do
   defp package do
     [
       files: ~w(lib .formatter.exs mix.exs README* LICENSE* CHANGELOG*),
-      licenses: ["Apache-2"],
+      licenses: ["Apache-2.0"],
       links: %{
         "GitHub" =>
           "https://github.com/open-telemetry/opentelemetry-erlang-contrib/tree/main/instrumentation/opentelemetry_redix",