Verified Commit 55a90e9c authored by Hercules Merscher's avatar Hercules Merscher 🌴
Browse files

fix: Sets OTel's default sampler to probabilistic (0.1%)

parent 3d81966c

lib/labkit/tracing/README.md

+5 −0
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@@ -84,6 +84,8 @@ The following connection string formats and query parameters are supported: 


### Sampling



**Default Behavior:** When no sampler is specified, probabilistic sampling is used with a **0.1% sample rate** (1 in 1000 traces).



- **`sampler`** - Sampling strategy (`probabilistic` or `const`)

  - `probabilistic` - Sample a percentage of traces (default: 0.1%)

  - `const` - Sample all traces (when `sampler_param=1`) or none (when `sampler_param=0`)
@@ -416,6 +418,9 @@ The tracing module includes built-in sanitization: 
Use sampling to control overhead:



```bash

# Default: 0.1% sampling (no sampler specified)

export GITLAB_TRACING="otlp://localhost:4318"



# Trace 1% of requests

export GITLAB_TRACING="otlp://localhost:4318?sampler=probabilistic&sampler_param=0.01"

lib/labkit/tracing/factory.rb

+3 −0
Original line number Diff line number Diff line
@@ -6,6 +6,9 @@ module Labkit 
    # distributed tracing system within the process, given the

    # tracing connection string

    class Factory

      # When the probabilistic sampler is used, by default 0.1% of requests will be traced

      DEFAULT_PROBABILISTIC_RATE = 0.001



      # @param service_name [String] The service name for the tracer

      # @param connection_string [String] The connection string (e.g., "otlp://localhost:4318")

      # @yield [config] Optional configuration block for OpenTelemetry SDK customization (OTLP only)

lib/labkit/tracing/jaeger_factory.rb

+1 −4
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@@ -10,9 +10,6 @@ module Labkit 
  module Tracing

    # JaegerFactory will configure Jaeger distributed tracing

    class JaegerFactory

      # When the probabilistic sampler is used, by default 0.1% of requests will be traced

      DEFAULT_PROBABILISTIC_RATE = 0.001



      # The default port for the Jaeger agent UDP listener

      DEFAULT_UDP_PORT = 6831
@@ -73,7 +70,7 @@ module Labkit 
      def self.get_sampler(sampler_type, sampler_param)

        case sampler_type

        when "probabilistic"

          sampler_rate = sampler_param ? sampler_param.to_f : DEFAULT_PROBABILISTIC_RATE

          sampler_rate = sampler_param ? sampler_param.to_f : Factory::DEFAULT_PROBABILISTIC_RATE

          Jaeger::Samplers::Probabilistic.new(rate: sampler_rate)

        when "const"

          const_value = sampler_param == "1"

lib/labkit/tracing/open_telemetry_factory.rb

+2 −5
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@@ -14,9 +14,6 @@ module Labkit 
    class OpenTelemetryFactory

      OTLP_SCHEME = "otlp"



      # When the probabilistic sampler is used, by default 0.1% of requests will be traced

      DEFAULT_PROBABILISTIC_RATE = 0.001



      # The default endpoint for OTLP HTTP exporter

      DEFAULT_HTTP_ENDPOINT = "http://localhost:4318/v1/traces"
@@ -174,7 +171,7 @@ module Labkit 
        def get_sampler(sampler_type, sampler_param)

          case sampler_type

          when "probabilistic"

            sampler_rate = sampler_param ? sampler_param.to_f : DEFAULT_PROBABILISTIC_RATE

            sampler_rate = sampler_param ? sampler_param.to_f : Factory::DEFAULT_PROBABILISTIC_RATE

            OpenTelemetry::SDK::Trace::Samplers::TraceIdRatioBased.new(sampler_rate)

          when "const"

            if sampler_param == "1"
@@ -183,7 +180,7 @@ module Labkit 
              OpenTelemetry::SDK::Trace::Samplers::ALWAYS_OFF

            end

          else

            OpenTelemetry::SDK::Trace::Samplers::ALWAYS_ON

            OpenTelemetry::SDK::Trace::Samplers::TraceIdRatioBased.new(Factory::DEFAULT_PROBABILISTIC_RATE)

          end

        end

spec/labkit/tracing/open_telemetry_factory_spec.rb

+2 −2
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@@ -326,9 +326,9 @@ describe Labkit::Tracing::OpenTelemetryFactory do 
  end



  describe ".get_sampler" do

    it "returns ALWAYS_ON for unknown sampler type" do

    it "returns probabilistic sampler with default rate for unknown sampler type" do

      sampler = described_class.send(:get_sampler, "unknown", nil)

      expect(sampler).to eq(OpenTelemetry::SDK::Trace::Samplers::ALWAYS_ON)

      expect(sampler).to be_a(OpenTelemetry::SDK::Trace::Samplers::TraceIdRatioBased)

    end



    it "returns ALWAYS_ON for const sampler with param 1" do