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chore(style): Error always comes as last return value #5

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merged 1 commit into from Sep 28, 2022
Merged

chore(style): Error always comes as last return value #5

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35 changes: 18 additions & 17 deletions observability/metrics.go
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Expand Up @@ -27,16 +27,16 @@ type MeterConfig struct {
ServiceVersion string
}

// OtelMeter takes a grpc connection to an otel collector, a collectPeriod time.Duration (more than a second), and
// sets the meter collector up and assigns it to a global meter. If the function returns nil, assume that the global
// meter is now set and ready to be used.
// OtelMeter takes a grpc connection to an otel collector, a MeterConfig that holds important data like collection
// period, service and namespace names, and the version of the application we're attaching the meter to. It then
// configures the meter provider, and returns a shutdown function and nil error if successful.
//
// This function merely sets up the scaffolding to ship collected metered data to the opentelemetry collector. It does
// not set up the specific meters for the applications.
func OtelMeter(ctx context.Context, conn *grpc.ClientConn, meterConfig MeterConfig) (error, func(context.Context) error) {
func OtelMeter(ctx context.Context, conn *grpc.ClientConn, meterConfig MeterConfig) (func(context.Context) error, error) {
if meterConfig.CollectPeriod < time.Second {
return errors.New("collect period is shorter than a second, please choose a longer period to avoid" +
" overloading the collector"), nil
return nil, errors.New("collect period is shorter than a second, please choose a longer period to avoid" +
" overloading the collector")
}

// exporter is the thing that will send the data from the app to wherever else it needs to go.
Expand All @@ -45,7 +45,7 @@ func OtelMeter(ctx context.Context, conn *grpc.ClientConn, meterConfig MeterConf
otlpmetricgrpc.WithGRPCConn(conn),
)
if err != nil {
return errors.Wrap(err, "otlpmetricgrpc.New"), nil
return nil, errors.Wrap(err, "otlpmetricgrpc.New")
}

// periodicReader is the thing that collects the data every cycle, and then uses the exporter above to send it
Expand All @@ -59,15 +59,16 @@ func OtelMeter(ctx context.Context, conn *grpc.ClientConn, meterConfig MeterConf
)

// resource configures the very basic attributes of every measurement taken.
r := resource.NewWithAttributes(
semconv.SchemaURL,
semconv.ServiceNameKey.String(meterConfig.ServiceName),
semconv.TelemetrySDKLanguageGo,
semconv.ServiceNamespaceKey.String(meterConfig.ServiceNamespace),
semconv.ServiceVersionKey.String(meterConfig.ServiceVersion),
semconv.DBSystemPostgreSQL,
attribute.String("exporter", "grpc"),
)
r, err := resource.Merge(
resource.Default(),
resource.NewWithAttributes(
semconv.SchemaURL,
semconv.ServiceNameKey.String(meterConfig.ServiceName),
semconv.ServiceNamespaceKey.String(meterConfig.ServiceNamespace),
semconv.ServiceVersionKey.String(meterConfig.ServiceVersion),
semconv.DBSystemPostgreSQL,
attribute.String("exporter", "grpc"),
))

// meterProvider takes the resource, and the reader, to provide a thing that we can create actual instruments out
// of, so we can start measuring things.
Expand All @@ -77,5 +78,5 @@ func OtelMeter(ctx context.Context, conn *grpc.ClientConn, meterConfig MeterConf
)

global.SetMeterProvider(meterProvider)
return nil, meterProvider.Shutdown
return meterProvider.Shutdown, nil
}