Go app framework
This commit is contained in:
54
pkg/otel/ctx.go
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54
pkg/otel/ctx.go
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@ -0,0 +1,54 @@
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package otel
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import (
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"context"
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"errors"
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"go.opentelemetry.io/otel/metric"
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"go.opentelemetry.io/otel/trace"
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)
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type otelCtxKey uint8
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const (
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ctxKeyTracer otelCtxKey = iota
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ctxKeyMeter
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)
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func MustTracerFromCtx(ctx context.Context) trace.Tracer {
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ctxData := ctx.Value(ctxKeyTracer)
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if ctxData == nil {
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panic(errors.New("no tracer found in context"))
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}
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tracer, ok := ctxData.(trace.Tracer)
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if !ok {
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panic(errors.New("invalid tracer found in context"))
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}
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return tracer
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}
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func AddTracerToCtx(ctx context.Context, tracer trace.Tracer) context.Context {
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ctx = context.WithValue(ctx, ctxKeyTracer, tracer)
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return ctx
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}
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func MustMeterFromCtx(ctx context.Context) metric.Meter {
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ctxData := ctx.Value(ctxKeyMeter)
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if ctxData == nil {
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panic(errors.New("no meter found in context"))
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}
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meter, ok := ctxData.(metric.Meter)
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if !ok {
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panic(errors.New("invalid meter found in context"))
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}
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return meter
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}
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func AddMeterToCtx(ctx context.Context, meter metric.Meter) context.Context {
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ctx = context.WithValue(ctx, ctxKeyMeter, meter)
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return ctx
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}
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227
pkg/otel/otel.go
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227
pkg/otel/otel.go
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@ -0,0 +1,227 @@
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package otel
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import (
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"context"
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"errors"
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"fmt"
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"os"
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"time"
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opentelemetry "go.opentelemetry.io/otel"
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"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc"
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"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc"
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"go.opentelemetry.io/otel/exporters/prometheus"
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"go.opentelemetry.io/otel/exporters/stdout/stdoutmetric"
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"go.opentelemetry.io/otel/exporters/stdout/stdouttrace"
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"gitea.libretechconsulting.com/rmcguire/go-app/pkg/config"
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noopMetric "go.opentelemetry.io/otel/metric/noop"
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"go.opentelemetry.io/otel/propagation"
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"go.opentelemetry.io/otel/sdk/metric"
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"go.opentelemetry.io/otel/sdk/resource"
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traceSDK "go.opentelemetry.io/otel/sdk/trace"
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semconv "go.opentelemetry.io/otel/semconv/v1.24.0"
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trace "go.opentelemetry.io/otel/trace"
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"go.opentelemetry.io/otel/trace/noop"
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)
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// OTEL Options
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var (
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EnableStdoutExporter Option = enableStdoutExporter{}
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EnablePrometheusExporter Option = enablePrometheusExporter{}
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// Overide the default metric export interval
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WithMetricExportInterval = func(interval time.Duration) Option {
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return exportInterval{interval: interval}
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}
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)
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const defMetricInterval = 15 * time.Second
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// Context must carry config.AppConfig
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func Init(ctx context.Context) (context.Context, func(context.Context) error) {
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cfg := config.MustFromCtx(ctx)
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// Nothing to do here if not enabled
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if !cfg.OTEL.Enabled {
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opentelemetry.SetMeterProvider(noopMetric.NewMeterProvider())
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opentelemetry.SetTracerProvider(noop.NewTracerProvider())
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return ctx, func(context.Context) error {
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return nil
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}
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}
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var (
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metricInterval = defMetricInterval
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options = make([]Option, 0)
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s = &settings{}
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shutdownFuncs []func(context.Context) error
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)
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// Prepare settings for OTEL from configuration
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if cfg.OTEL.StdoutEnabled {
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options = append(options, EnableStdoutExporter)
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}
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if cfg.OTEL.MetricIntervalSecs > 0 {
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metricInterval = time.Duration(cfg.OTEL.MetricIntervalSecs) * time.Second
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}
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if cfg.OTEL.PrometheusEnabled {
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options = append(options, EnablePrometheusExporter)
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}
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options = append(options,
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WithMetricExportInterval(metricInterval))
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// Apply settings
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for _, opt := range options {
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opt.apply(s)
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}
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// shutdown calls cleanup functions registered via shutdownFuncs.
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// The errors from the calls are joined.
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// Each registered cleanup will be invoked once.
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shutdown := func(ctx context.Context) error {
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var err error
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for _, fn := range shutdownFuncs {
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err = errors.Join(err, fn(ctx))
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}
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shutdownFuncs = nil
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return err
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}
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// handleErr calls shutdown for cleanup and makes sure that all errors are returned.
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handleErr := func(inErr error) {
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if err := errors.Join(inErr, shutdown(ctx)); err != nil {
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fmt.Fprintln(os.Stderr, "OTEL Error:", err)
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}
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}
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// Set up meter provider.
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meterProvider, err := s.newMeterProvider(ctx)
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if err != nil {
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handleErr(err)
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return ctx, shutdown
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}
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shutdownFuncs = append(shutdownFuncs, meterProvider.Shutdown)
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opentelemetry.SetMeterProvider(meterProvider)
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meter := opentelemetry.Meter(cfg.Name)
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ctx = AddMeterToCtx(ctx, meter)
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// Set up tracing
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opentelemetry.SetTextMapPropagator(newPropagator())
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var tracerProvider *traceSDK.TracerProvider
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tracerProvider, err = s.newTracerProvider(ctx)
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if err != nil {
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handleErr(err)
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return ctx, shutdown
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}
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shutdownFuncs = append(shutdownFuncs, tracerProvider.Shutdown)
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opentelemetry.SetTracerProvider(tracerProvider)
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tracer := opentelemetry.Tracer(cfg.Name)
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ctx = AddTracerToCtx(ctx, tracer)
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return ctx, shutdown
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}
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func newPropagator() propagation.TextMapPropagator {
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return propagation.NewCompositeTextMapPropagator(
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propagation.TraceContext{},
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propagation.Baggage{},
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)
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}
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func (s *settings) newTracerProvider(ctx context.Context) (traceProvider *traceSDK.TracerProvider, err error) {
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traceOpts := []traceSDK.TracerProviderOption{
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traceSDK.WithResource(newResource()),
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}
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host, set := os.LookupEnv("OTEL_EXPORTER_OTLP_ENDPOINT")
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if set && host != "" {
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exporter, err := otlptracegrpc.New(ctx)
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if err != nil {
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return nil, err
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}
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traceOpts = append(traceOpts, traceSDK.WithBatcher(exporter))
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}
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if s.EnableStdoutExporter {
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stdoutExporter, err := stdouttrace.New(stdouttrace.WithPrettyPrint())
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if err != nil {
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return nil, err
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}
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traceOpts = append(traceOpts, traceSDK.WithBatcher(stdoutExporter))
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}
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traceProvider = traceSDK.NewTracerProvider(traceOpts...)
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return
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}
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func newResource() *resource.Resource {
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return resource.NewWithAttributes(semconv.SchemaURL)
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}
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// Configures meter provider
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// Always provides a prometheus metrics exporter
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// Conditionally provides an OTLP metrics exporter
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func (s *settings) newMeterProvider(ctx context.Context) (*metric.MeterProvider, error) {
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// OTEL Prometheus Exporter
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exporter, err := prometheus.New()
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if err != nil {
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return nil, err
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}
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metricOptions := make([]metric.Option, 0, 5)
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if s.EnableStdoutExporter {
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stdoutMetricExporter, err := stdoutmetric.New()
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if err != nil {
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return nil, err
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}
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metricOptions = append(metricOptions,
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metric.WithReader(metric.NewPeriodicReader(stdoutMetricExporter)),
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)
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}
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host, set := os.LookupEnv("OTEL_EXPORTER_OTLP_ENDPOINT")
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var otlpExporter *otlpmetricgrpc.Exporter
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if set && host != "" {
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if exp, err := otlpmetricgrpc.New(ctx, otlpmetricgrpc.WithInsecure()); err != nil {
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return nil, fmt.Errorf("otlpmetricgrpc.New: %w", err)
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} else {
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otlpExporter = exp
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}
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}
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var meterProvider *metric.MeterProvider
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if otlpExporter != nil {
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metricOptions = append(metricOptions,
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metric.WithReader(exporter),
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metric.WithReader(
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metric.NewPeriodicReader(
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otlpExporter,
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metric.WithInterval(s.MetricExportInterval),
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),
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),
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metric.WithResource(newResource()),
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)
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} else {
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metricOptions = append(metricOptions,
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metric.WithReader(exporter),
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metric.WithResource(newResource()),
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)
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}
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meterProvider = metric.NewMeterProvider(metricOptions...)
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return meterProvider, nil
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}
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// Creates a new tracer from the global opentelemetry provider
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func NewTracer(options ...trace.TracerOption) trace.Tracer {
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return opentelemetry.GetTracerProvider().Tracer(
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os.Getenv("OTEL_SERVICE_NAME"),
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options...,
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)
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}
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38
pkg/otel/settings.go
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38
pkg/otel/settings.go
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@ -0,0 +1,38 @@
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package otel
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import "time"
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type settings struct {
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EnableStdoutExporter bool
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EnablePrometheusExporter bool
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MetricExportInterval time.Duration
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}
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type Option interface {
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apply(*settings)
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}
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type enableStdoutExporter struct {
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Option
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}
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func (setting enableStdoutExporter) apply(o *settings) {
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o.EnableStdoutExporter = true
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}
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type enablePrometheusExporter struct {
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Option
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}
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func (setting enablePrometheusExporter) apply(o *settings) {
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o.EnablePrometheusExporter = true
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}
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type exportInterval struct {
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Option
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interval time.Duration
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}
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func (setting exportInterval) apply(o *settings) {
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o.MetricExportInterval = setting.interval
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}
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30
pkg/otel/util.go
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30
pkg/otel/util.go
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@ -0,0 +1,30 @@
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package otel
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import (
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"context"
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"strings"
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"go.opentelemetry.io/otel"
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"go.opentelemetry.io/otel/metric"
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"go.opentelemetry.io/otel/trace"
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"gitea.libretechconsulting.com/rmcguire/go-app/pkg/config"
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)
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func GetTracer(ctx context.Context, components ...string) trace.Tracer {
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return otel.Tracer(getName(ctx, components...))
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}
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func GetMeter(ctx context.Context, components ...string) metric.Meter {
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return otel.Meter(getName(ctx, components...))
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}
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func getName(ctx context.Context, components ...string) string {
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cfg := config.MustFromCtx(ctx)
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path := make([]string, 0, len(components)+1)
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path = append(path, cfg.Name)
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path = append(path, components...)
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return strings.Join(path, ".")
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}
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