|
| 1 | +package tracing |
| 2 | + |
| 3 | +import ( |
| 4 | + "context" |
| 5 | + "os" |
| 6 | + "strconv" |
| 7 | + |
| 8 | + "go.opentelemetry.io/otel" |
| 9 | + "go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc" |
| 10 | + "go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp" |
| 11 | + "go.opentelemetry.io/otel/propagation" |
| 12 | + "go.opentelemetry.io/otel/sdk/resource" |
| 13 | + sdktrace "go.opentelemetry.io/otel/sdk/trace" |
| 14 | + semconv "go.opentelemetry.io/otel/semconv/v1.40.0" |
| 15 | + "go.uber.org/zap" |
| 16 | +) |
| 17 | + |
| 18 | +const ( |
| 19 | + EnvOTLPEndpoint = "OTEL_EXPORTER_OTLP_ENDPOINT" |
| 20 | + EnvOTLPProtocol = "OTEL_EXPORTER_OTLP_PROTOCOL" |
| 21 | + EnvOTLPTracesProtocol = "OTEL_EXPORTER_OTLP_TRACES_PROTOCOL" |
| 22 | + EnvTracesSampler = "OTEL_TRACES_SAMPLER" |
| 23 | + EnvTracesSamplerArg = "OTEL_TRACES_SAMPLER_ARG" |
| 24 | + |
| 25 | + protocolGRPC = "grpc" |
| 26 | + protocolHTTP = "http/protobuf" |
| 27 | +) |
| 28 | + |
| 29 | +type TracerProvider struct { |
| 30 | + shutdown func(context.Context) error |
| 31 | +} |
| 32 | + |
| 33 | +func New(logger *zap.SugaredLogger) *TracerProvider { |
| 34 | + if os.Getenv(EnvOTLPEndpoint) == "" { |
| 35 | + logger.Info("OTLP endpoint not configured, using noop tracer provider") |
| 36 | + return noopProvider() |
| 37 | + } |
| 38 | + if os.Getenv(EnvTracesSampler) == "" { |
| 39 | + logger.Info("OTEL_TRACES_SAMPLER not set, tracing disabled (set explicitly to opt in)") |
| 40 | + return noopProvider() |
| 41 | + } |
| 42 | + |
| 43 | + proto := protocolFromEnv() |
| 44 | + exporter, err := newExporter(context.Background(), logger, proto) |
| 45 | + if err != nil { |
| 46 | + logger.Errorw("failed to create OTLP exporter, using noop tracer provider", "error", err) |
| 47 | + return noopProvider() |
| 48 | + } |
| 49 | + |
| 50 | + res, err := resource.Merge( |
| 51 | + resource.Default(), |
| 52 | + resource.NewWithAttributes( |
| 53 | + semconv.SchemaURL, |
| 54 | + semconv.ServiceName(TracerName), |
| 55 | + ), |
| 56 | + ) |
| 57 | + if err != nil { |
| 58 | + logger.Errorw("failed to create resource", "error", err) |
| 59 | + res = resource.Default() |
| 60 | + } |
| 61 | + |
| 62 | + tp := sdktrace.NewTracerProvider( |
| 63 | + sdktrace.WithBatcher(exporter), |
| 64 | + sdktrace.WithResource(res), |
| 65 | + sdktrace.WithSampler(samplerFromEnv(logger)), |
| 66 | + ) |
| 67 | + |
| 68 | + otel.SetTracerProvider(tp) |
| 69 | + otel.SetTextMapPropagator(propagation.TraceContext{}) |
| 70 | + |
| 71 | + logger.Infow("tracing initialized", "endpoint", os.Getenv(EnvOTLPEndpoint), "protocol", proto) |
| 72 | + |
| 73 | + return &TracerProvider{shutdown: tp.Shutdown} |
| 74 | +} |
| 75 | + |
| 76 | +func noopProvider() *TracerProvider { |
| 77 | + return &TracerProvider{shutdown: func(context.Context) error { return nil }} |
| 78 | +} |
| 79 | + |
| 80 | +func protocolFromEnv() string { |
| 81 | + if v := os.Getenv(EnvOTLPTracesProtocol); v != "" { |
| 82 | + return v |
| 83 | + } |
| 84 | + if v := os.Getenv(EnvOTLPProtocol); v != "" { |
| 85 | + return v |
| 86 | + } |
| 87 | + return protocolGRPC |
| 88 | +} |
| 89 | + |
| 90 | +func newExporter(ctx context.Context, logger *zap.SugaredLogger, proto string) (sdktrace.SpanExporter, error) { |
| 91 | + endpoint := os.Getenv(EnvOTLPEndpoint) |
| 92 | + switch proto { |
| 93 | + case protocolHTTP: |
| 94 | + return otlptracehttp.New(ctx, otlptracehttp.WithEndpointURL(endpoint)) |
| 95 | + case protocolGRPC: |
| 96 | + return otlptracegrpc.New(ctx, otlptracegrpc.WithEndpointURL(endpoint)) |
| 97 | + default: |
| 98 | + logger.Errorw("unsupported OTLP protocol; falling back to grpc", "protocol", proto) |
| 99 | + return otlptracegrpc.New(ctx, otlptracegrpc.WithEndpointURL(endpoint)) |
| 100 | + } |
| 101 | +} |
| 102 | + |
| 103 | +func (tp *TracerProvider) Shutdown(ctx context.Context) error { |
| 104 | + if tp.shutdown != nil { |
| 105 | + return tp.shutdown(ctx) |
| 106 | + } |
| 107 | + return nil |
| 108 | +} |
| 109 | + |
| 110 | +func samplerFromEnv(logger *zap.SugaredLogger) sdktrace.Sampler { |
| 111 | + name := os.Getenv(EnvTracesSampler) |
| 112 | + argStr := os.Getenv(EnvTracesSamplerArg) |
| 113 | + arg, err := strconv.ParseFloat(argStr, 64) |
| 114 | + if err != nil && argStr != "" { |
| 115 | + logger.Errorw("ignoring malformed sampler argument", "env", EnvTracesSamplerArg, "value", argStr) |
| 116 | + } |
| 117 | + if argStr == "" && (name == "traceidratio" || name == "parentbased_traceidratio") { |
| 118 | + logger.Infow("ratio sampler selected without "+EnvTracesSamplerArg+"; defaulting to 0% sampling", "env", EnvTracesSampler, "value", name) |
| 119 | + } |
| 120 | + switch name { |
| 121 | + case "always_on": |
| 122 | + return sdktrace.AlwaysSample() |
| 123 | + case "always_off": |
| 124 | + return sdktrace.NeverSample() |
| 125 | + case "traceidratio": |
| 126 | + return sdktrace.TraceIDRatioBased(arg) |
| 127 | + case "parentbased_always_on": |
| 128 | + return sdktrace.ParentBased(sdktrace.AlwaysSample()) |
| 129 | + case "parentbased_always_off": |
| 130 | + return sdktrace.ParentBased(sdktrace.NeverSample()) |
| 131 | + case "parentbased_traceidratio": |
| 132 | + return sdktrace.ParentBased(sdktrace.TraceIDRatioBased(arg)) |
| 133 | + } |
| 134 | + logger.Warnw("unrecognized OTEL_TRACES_SAMPLER value; falling back to never sample", "value", name) |
| 135 | + return sdktrace.NeverSample() |
| 136 | +} |
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