gzip otel payload

lib/braintrust/config.rb

@@ -5,17 +5,18 @@ module Braintrust
   # and allows overriding with explicit options
   class Config
     attr_reader :api_key, :org_name, :default_project, :app_url, :api_url,
-      :filter_ai_spans, :span_filter_funcs
+      :filter_ai_spans, :span_filter_funcs, :compress_otel_payload
 
     def initialize(api_key: nil, org_name: nil, default_project: nil, app_url: nil, api_url: nil,
-      filter_ai_spans: nil, span_filter_funcs: nil)
+      filter_ai_spans: nil, span_filter_funcs: nil, compress_otel_payload: true)
       @api_key = api_key
       @org_name = org_name
       @default_project = default_project
       @app_url = app_url
       @api_url = api_url
       @filter_ai_spans = filter_ai_spans
       @span_filter_funcs = span_filter_funcs || []
+      @compress_otel_payload = compress_otel_payload
     end
 
     # Create a Config from environment variables, with option overrides
@@ -27,9 +28,10 @@ def initialize(api_key: nil, org_name: nil, default_project: nil, app_url: nil,
     # @param api_url [String, nil] API URL (overrides BRAINTRUST_API_URL env var)
     # @param filter_ai_spans [Boolean, nil] Enable AI span filtering (overrides BRAINTRUST_OTEL_FILTER_AI_SPANS env var)
     # @param span_filter_funcs [Array<Proc>, nil] Custom span filter functions
+    # @param compress_otel_payload [Boolean, nil] Gzip OTEL export payloads (overrides BRAINTRUST_COMPRESS_OTEL_PAYLOAD env var). Default: true
     # @return [Config] the created config
     def self.from_env(api_key: nil, org_name: nil, default_project: nil, app_url: nil, api_url: nil,
-      filter_ai_spans: nil, span_filter_funcs: nil)
+      filter_ai_spans: nil, span_filter_funcs: nil, compress_otel_payload: nil)
       # Parse filter_ai_spans from ENV if not explicitly provided
       env_filter_ai_spans = ENV["BRAINTRUST_OTEL_FILTER_AI_SPANS"]
       filter_ai_spans_value = if filter_ai_spans.nil?
@@ -38,15 +40,31 @@ def self.from_env(api_key: nil, org_name: nil, default_project: nil, app_url: ni
         filter_ai_spans
       end
 
+      # Gzip OTEL payloads by default; disable via env var if not explicitly provided
+      compress_otel_payload_value = if compress_otel_payload.nil?
+        parse_bool(ENV["BRAINTRUST_COMPRESS_OTEL_PAYLOAD"], default: true)
+      else
+        compress_otel_payload
+      end
+
       new(
         api_key: api_key || ((ENV["BRAINTRUST_API_KEY"] && ENV["BRAINTRUST_API_KEY"].empty?) ? nil : ENV["BRAINTRUST_API_KEY"]),
         org_name: org_name || ENV["BRAINTRUST_ORG_NAME"],
         default_project: default_project || ENV["BRAINTRUST_DEFAULT_PROJECT"],
         app_url: app_url || ENV["BRAINTRUST_APP_URL"] || "https://www.braintrust.dev",
         api_url: api_url || ENV["BRAINTRUST_API_URL"] || "https://api.braintrust.dev",
         filter_ai_spans: filter_ai_spans_value,
-        span_filter_funcs: span_filter_funcs
+        span_filter_funcs: span_filter_funcs,
+        compress_otel_payload: compress_otel_payload_value
       )
     end
+
+    # Parse a boolean-ish env var value. Falsy values: "false", "0", "no", "off"
+    # (case-insensitive). nil/empty falls back to the default.
+    def self.parse_bool(value, default:)
+      return default if value.nil? || value.empty?
+
+      !%w[false 0 no off].include?(value.strip.downcase)
+    end
   end
 end

lib/braintrust/trace.rb

@@ -89,9 +89,11 @@ def self.enable(tracer_provider, state: nil, exporter: nil, config: nil)
       config ||= state.respond_to?(:config) ? state.config : nil
 
       # Create OTLP HTTP exporter unless override provided
+      compress = config.nil? || config.compress_otel_payload
       exporter ||= SpanExporter.new(
         endpoint: "#{state.api_url}/otel/v1/traces",
-        api_key: state.api_key
+        api_key: state.api_key,
+        compress: compress
       )
 
       # Use SimpleSpanProcessor for InMemorySpanExporter (testing), BatchSpanProcessor for production

lib/braintrust/trace/span_exporter.rb

@@ -17,8 +17,12 @@ class SpanExporter < OpenTelemetry::Exporter::OTLP::Exporter
       SUCCESS = OpenTelemetry::SDK::Trace::Export::SUCCESS
       FAILURE = OpenTelemetry::SDK::Trace::Export::FAILURE
 
-      def initialize(endpoint:, api_key:)
-        super(endpoint: endpoint, headers: {"Authorization" => "Bearer #{api_key}"})
+      def initialize(endpoint:, api_key:, compress: true)
+        super(
+          endpoint: endpoint,
+          headers: {"Authorization" => "Bearer #{api_key}"},
+          compression: compress ? "gzip" : "none"
+        )
       end
 
       def export(span_data, timeout: nil)

test/braintrust/config_test.rb

@@ -6,7 +6,8 @@
   "BRAINTRUST_API_KEY" => ENV["BRAINTRUST_API_KEY"],
   "BRAINTRUST_ORG_NAME" => ENV["BRAINTRUST_ORG_NAME"],
   "BRAINTRUST_APP_URL" => ENV["BRAINTRUST_APP_URL"],
-  "BRAINTRUST_API_URL" => ENV["BRAINTRUST_API_URL"]
+  "BRAINTRUST_API_URL" => ENV["BRAINTRUST_API_URL"],
+  "BRAINTRUST_COMPRESS_OTEL_PAYLOAD" => ENV["BRAINTRUST_COMPRESS_OTEL_PAYLOAD"]
 }.freeze
 
 class Braintrust::ConfigTest < Minitest::Test
@@ -61,4 +62,37 @@ def test_env_vars_override_defaults
 
     assert_equal "https://custom.braintrust.dev", config.app_url
   end
+
+  def test_compress_otel_payload_defaults_to_true
+    config = Braintrust::Config.from_env
+
+    assert_equal true, config.compress_otel_payload
+  end
+
+  def test_compress_otel_payload_disabled_by_env_var
+    %w[false 0 no off FALSE Off].each do |val|
+      ENV["BRAINTRUST_COMPRESS_OTEL_PAYLOAD"] = val
+
+      config = Braintrust::Config.from_env
+
+      assert_equal false, config.compress_otel_payload,
+        "expected #{val.inspect} to disable compression"
+    end
+  end
+
+  def test_compress_otel_payload_truthy_env_var
+    ENV["BRAINTRUST_COMPRESS_OTEL_PAYLOAD"] = "true"
+
+    config = Braintrust::Config.from_env
+
+    assert_equal true, config.compress_otel_payload
+  end
+
+  def test_compress_otel_payload_explicit_overrides_env_var
+    ENV["BRAINTRUST_COMPRESS_OTEL_PAYLOAD"] = "false"
+
+    config = Braintrust::Config.from_env(compress_otel_payload: true)
+
+    assert_equal true, config.compress_otel_payload
+  end
 end

test/braintrust/trace/span_exporter_test.rb

@@ -163,6 +163,25 @@ def test_empty_span_data
     assert_equal 0, exporter.calls.length
   end
 
+  def test_uses_gzip_compression_by_default
+    exporter = Braintrust::Trace::SpanExporter.new(
+      endpoint: "https://example.com/otel/v1/traces",
+      api_key: "test-key"
+    )
+
+    assert_equal "gzip", exporter.instance_variable_get(:@compression)
+  end
+
+  def test_compression_disabled_when_compress_false
+    exporter = Braintrust::Trace::SpanExporter.new(
+      endpoint: "https://example.com/otel/v1/traces",
+      api_key: "test-key",
+      compress: false
+    )
+
+    assert_equal "none", exporter.instance_variable_get(:@compression)
+  end
+
   def test_header_cleaned_up_even_on_error
     exporter = RecordingExporter.new
     exporter.define_singleton_method(:send_bytes) do |data, timeout:|