chore: fix config tests; make noop global meter

Signed-off-by: Mark Phelps <[email protected]>

internal/cmd/grpc.go

@@ -43,7 +43,7 @@ import (
 	"go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc"
 	"go.opentelemetry.io/otel"
 	metric "go.opentelemetry.io/otel/metric"
-	metricsnoop "go.opentelemetry.io/otel/metric/noop"
+	metricnoop "go.opentelemetry.io/otel/metric/noop"
 	metricsdk "go.opentelemetry.io/otel/sdk/metric"
 	tracesdk "go.opentelemetry.io/otel/sdk/trace"
 	"go.uber.org/zap"
@@ -155,7 +155,7 @@ func NewGRPCServer(
 	logger.Debug("store enabled", zap.Stringer("store", store))
 
 	// Default to a no-op OTEL meter provider
-	var meterProvider metric.MeterProvider = metricsnoop.NewMeterProvider()
+	var meterProvider metric.MeterProvider = metricnoop.NewMeterProvider()
 
 	// Initialize metrics exporter if enabled
 	if cfg.Metrics.Enabled {

internal/config/config.go

@@ -556,6 +556,11 @@ func Default() *Config {
 			GRPCPort:  9000,
 		},
 
+		Metrics: MetricsConfig{
+			Enabled:  true,
+			Exporter: MetricsPrometheus,
+		},
+
 		Tracing: TracingConfig{
 			Enabled:       false,
 			Exporter:      TracingJaeger,

internal/config/config_test.go

@@ -323,6 +323,15 @@ func TestLoad(t *testing.T) {
 				return cfg
 			},
 		},
+		{
+			name: "metrics disabled",
+			path: "./testdata/metrics/disabled.yml",
+			expected: func() *Config {
+				cfg := Default()
+				cfg.Metrics.Enabled = false
+				return cfg
+			},
+		},
 		{
 			name: "tracing zipkin",
 			path: "./testdata/tracing/zipkin.yml",

internal/config/metrics.go

@@ -16,22 +16,19 @@ const (
 )
 
 type MetricsConfig struct {
-	Enabled  bool            `json:"enabled" mapstructure:"enabled" yaml:"enabled"`
-	Exporter MetricsExporter `json:"exporter,omitempty" mapstructure:"exporter" yaml:"exporter,omitempty"`
-	OTLP     *OTLPConfig     `json:"otlp,omitempty" mapstructure:"otlp" yaml:"otlp,omitempty"`
+	Enabled  bool               `json:"enabled" mapstructure:"enabled" yaml:"enabled"`
+	Exporter MetricsExporter    `json:"exporter,omitempty" mapstructure:"exporter" yaml:"exporter,omitempty"`
+	OTLP     *OTLPMetricsConfig `json:"otlp,omitempty" mapstructure:"otlp" yaml:"otlp,omitempty"`
 }
 
-type OTLPConfig struct {
+type OTLPMetricsConfig struct {
 	Endpoint string `json:"endpoint,omitempty" mapstructure:"endpoint" yaml:"endpoint,omitempty"`
 }
 
 func (c *MetricsConfig) setDefaults(v *viper.Viper) error {
 	v.SetDefault("metrics", map[string]interface{}{
 		"enabled":  true,
 		"exporter": MetricsPrometheus,
-		"otlp": map[string]interface{}{
-			"endpoint": "localhost:4317",
-		},
 	})
 
 	return nil

internal/config/testdata/marshal/yaml/default.yml

@@ -24,6 +24,9 @@ server:
   http_port: 8080
   https_port: 443
   grpc_port: 9000
+metrics:
+  enabled: true
+  exporter: prometheus
 storage:
   type: database
 diagnostics:

internal/config/testdata/metrics/disabled.yml

@@ -0,0 +1,3 @@
+metrics:
+  enabled: false
+  exporter: prometheus

internal/metrics/metrics.go

@@ -11,12 +11,22 @@ import (
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp"
 	"go.opentelemetry.io/otel/exporters/prometheus"
 	"go.opentelemetry.io/otel/metric"
+	metricnoop "go.opentelemetry.io/otel/metric/noop"
 	sdkmetric "go.opentelemetry.io/otel/sdk/metric"
 )
 
 // Meter is the default Flipt-wide otel metric Meter.
 var Meter metric.Meter
 
+func init() {
+	// If the global Meter is nil, create a new noop Meter.
+	// Useful for testing.
+	if Meter == nil {
+		meterProvider := metricnoop.NewMeterProvider()
+		Meter = meterProvider.Meter("github.com/flipt-io/flipt")
+	}
+}
+
 // MustInt64 returns an instrument provider based on the global Meter.
 // The returns provider panics instead of returning an error when it cannot build
 // a required counter, upDownCounter or histogram.