fix: instrument unit must be an atom not the number 1 (#950)

* fix: instrument unit must be an atom not the number 1

* fix: make description optional in metrics protobuf map

* chore: ignore eqwalizer complaining about matchspec

Author: tsloughter

apps/opentelemetry_api_experimental/src/otel_instrument.erl

@@ -41,9 +41,9 @@
 
 -type advisory_params() :: #{explicit_bucket_boundaries => [number(), ...]}.
 
--type opts() :: #{description => description(),
-                  unit => unit(),
-                  advisory_params => advisory_params()}.
+-type opts() :: #{description => description() | undefined,
+                  unit => unit() | undefined,
+                  advisory_params => advisory_params() | undefined}.
 
 -type t() :: #instrument{}.
 

apps/opentelemetry_experimental/include/otel_metrics.hrl

@@ -115,7 +115,7 @@
         {
          name :: otel_view:name(),
          scope :: opentelemetry:instrumentation_scope() | undefined,
-         description :: otel_instrument:description(),
-         unit :: otel_instrument:unit(),
+         description :: otel_instrument:description() | undefined,
+         unit :: otel_instrument:unit() | undefined,
          data :: #sum{} | #gauge{} | #histogram{}
         }).

apps/opentelemetry_experimental/src/otel_otlp_metrics.erl

@@ -63,11 +63,16 @@ to_proto(#metric{name=Name,
                  data=Data}) ->
     Metric =
         #{name => otel_otlp_common:to_binary(Name),
-          description => Description,
           data => to_data(Data)},
-    case Unit of
-        undefined -> Metric;
-        _ -> Metric#{unit => otel_otlp_common:to_binary(Unit)}
+
+    Metric1 = case Unit of
+                  undefined -> Metric;
+                  _ -> Metric#{unit => otel_otlp_common:to_binary(Unit)}
+              end,
+
+    case Description of
+        undefined -> Metric1;
+        _ -> Metric1#{description => Description}
     end.
 
 to_data(#sum{aggregation_temporality=Temporality,

apps/opentelemetry_experimental/src/otel_view.erl

@@ -49,8 +49,6 @@
               criteria/0,
               config/0]).
 
--eqwalizer({nowarn_function, maybe_init_meter/3}).
-
 -include_lib("opentelemetry_api/include/gradualizer.hrl").
 
 %% ignore dialyzer warnings in functions using matchspecs or related to those that do
@@ -182,6 +180,7 @@ criteria_to_instrument_matchspec(_) ->
     %% eqwalizer:ignore using ignore as an ets matchspec workaround
     ets:match_spec_compile([{#instrument{_='_'}, [], [true]}]).
 
+%% eqwalizer:ignore using ignore as an ets matchspec workaround
 maybe_init_meter(#instrument{meter='_'}) ->
     %% eqwalizer:ignore using ignore as an ets matchspec workaround
     {'_', #meter{instrumentation_scope=#instrumentation_scope{_='_'},

apps/opentelemetry_experimental/test/otel_metrics_SUITE.erl

@@ -1774,7 +1774,7 @@ async_cumulative_page_faults(_Config) ->
 
     CounterName = page_faults,
     CounterDesc = <<"number of page faults">>,
-    CounterUnit = 1,
+    CounterUnit = '1',
 
     ?assert(otel_meter_server:add_view(#{instrument_name => CounterName},
                                        #{aggregation_module => otel_aggregation_sum})),
@@ -1834,7 +1834,7 @@ async_delta_page_faults(_Config) ->
 
     CounterName = page_faults,
     CounterDesc = <<"number of page faults">>,
-    CounterUnit = 1,
+    CounterUnit = '1',
 
     ?assert(otel_meter_server:add_view(#{instrument_name => CounterName},
                                        #{aggregation_module => otel_aggregation_sum})),
@@ -1915,7 +1915,7 @@ async_attribute_removal(_Config) ->
 
     CounterName = page_faults,
     CounterDesc = <<"number of page faults">>,
-    CounterUnit = 1,
+    CounterUnit = '1',
 
     ?assert(otel_meter_server:add_view(#{instrument_name => CounterName},
                                        #{aggregation_module => otel_aggregation_sum,