feat: Add option to enable compression of event payloads (#291)

contract-tests/client_entity.rb

@@ -36,6 +36,7 @@ def initialize(log, config)
       opts[:private_attributes] = events[:globalPrivateAttributes]
       opts[:flush_interval] = (events[:flushIntervalMs] / 1_000) unless events[:flushIntervalMs].nil?
       opts[:omit_anonymous_contexts] = !!events[:omitAnonymousContexts]
+      opts[:compress_events] = !!events[:enableGzip]
     else
       opts[:send_events] = false
     end

contract-tests/service.rb

@@ -34,6 +34,8 @@
       'secure-mode-hash',
       'tags',
       'migrations',
+      'event-gzip',
+      'optional-event-gzip',
       'event-sampling',
       'context-comparison',
       'polling-gzip',

launchdarkly-server-sdk.gemspec

@@ -39,6 +39,7 @@ Gem::Specification.new do |spec|
   spec.add_runtime_dependency "concurrent-ruby", "~> 1.1"
   spec.add_runtime_dependency "ld-eventsource", "2.2.2"
   spec.add_runtime_dependency "observer", "~> 0.1.2"
+  spec.add_runtime_dependency "zlib", "~> 3.1" unless RUBY_PLATFORM == "java"
   # Please keep ld-eventsource dependency as an exact version so that bugfixes to
   # that LD library are always associated with a new SDK version.
 

lib/ldclient-rb/config.rb

@@ -65,6 +65,7 @@ def initialize(opts = {})
       @all_attributes_private = opts[:all_attributes_private] || false
       @private_attributes = opts[:private_attributes] || []
       @send_events = opts.has_key?(:send_events) ? opts[:send_events] : Config.default_send_events
+      @compress_events = opts.has_key?(:compress_events) ? opts[:compress_events] : Config.default_compress_events
       @context_keys_capacity = opts[:context_keys_capacity] || Config.default_context_keys_capacity
       @context_keys_flush_interval = opts[:context_keys_flush_interval] || Config.default_context_keys_flush_interval
       @data_source = opts[:data_source]
@@ -254,6 +255,17 @@ def offline?
     #
     attr_reader :send_events
 
+    #
+    # Should the event payload sent to LaunchDarkly use gzip compression. By default this is false to prevent backward
+    # breaking compatibility issues with older versions of the relay proxy.
+    #
+    # Customers not using the relay proxy are strongly encouraged to enable this feature to reduce egress bandwidth
+    # cost.
+    #
+    # @return [Boolean]
+    #
+    attr_reader :compress_events
+
     #
     # The number of context keys that the event processor can remember at any one time. This reduces the
     # amount of duplicate context details sent in analytics events.
@@ -539,6 +551,14 @@ def self.default_send_events
       true
     end
 
+    #
+    # The default value for {#compress_events}.
+    # @return [Boolean] false
+    #
+    def self.default_compress_events
+      false
+    end
+
     #
     # The default value for {#context_keys_capacity}.
     # @return [Integer] 1000

lib/ldclient-rb/impl/event_sender.rb

@@ -2,6 +2,8 @@
 
 require "securerandom"
 require "http"
+require "stringio"
+require "zlib"
 
 module LaunchDarkly
   module Impl
@@ -42,14 +44,24 @@ def send_event_data(event_data, description, is_diagnostic)
               @logger.debug { "[LDClient] sending #{description}: #{event_data}" }
               headers = {}
               headers["content-type"] = "application/json"
+              headers["content-encoding"] = "gzip" if @config.compress_events
               Impl::Util.default_http_headers(@sdk_key, @config).each { |k, v| headers[k] = v }
               unless is_diagnostic
                 headers["X-LaunchDarkly-Event-Schema"] = CURRENT_SCHEMA_VERSION.to_s
                 headers["X-LaunchDarkly-Payload-ID"] = payload_id
               end
+
+              body = event_data
+              if @config.compress_events
+                gzip = Zlib::GzipWriter.new(StringIO.new)
+                gzip << event_data
+
+                body = gzip.close.string
+              end
+
               response = http_client.request("POST", uri, {
                 headers: headers,
-                body: event_data,
+                body: body,
               })
             rescue StandardError => exn
               @logger.warn { "[LDClient] Error sending events: #{exn.inspect}." }

spec/http_util.rb

@@ -1,14 +1,17 @@
 require "webrick"
 require "webrick/httpproxy"
 require "webrick/https"
+require "stringio"
+require "zlib"
 
 class StubHTTPServer
   attr_reader :requests, :port
 
   @@next_port = 50000
 
-  def initialize
+  def initialize(enable_compression: false)
     @port = StubHTTPServer.next_port
+    @enable_compression = enable_compression
     begin
       base_opts = {
         BindAddress: '127.0.0.1',
@@ -73,14 +76,16 @@ def record_request(req, res)
     @requests_queue << [req, req.body]
   end
 
-  def await_request
-    r = @requests_queue.pop
-    r[0]
-  end
-
   def await_request_with_body
     r = @requests_queue.pop
-    [r[0], r[1]]
+    request = r[0]
+    body = r[1]
+
+    return [request, body.to_s] unless @enable_compression
+
+    gz = Zlib::GzipReader.new(StringIO.new(body.to_s))
+
+    [request, gz.read]
   end
 end
 
@@ -90,8 +95,8 @@ def method_missing(*)
   end
 end
 
-def with_server(server = nil)
-  server = StubHTTPServer.new if server.nil?
+def with_server(enable_compression: false)
+  server = StubHTTPServer.new(enable_compression: enable_compression)
   begin
     server.start
     yield server

spec/impl/event_sender_spec.rb

@@ -11,24 +11,48 @@ module Impl
       subject { EventSender }
 
       let(:sdk_key) { "sdk_key" }
-      let(:fake_data) { '{"things":[]}' }
+      let(:fake_data) { '{"things":[],"stuff":false,"other examples":["you", "me", "us", "we"]}' }
 
-      def make_sender(server)
-        make_sender_with_events_uri(server.base_uri.to_s)
+      def make_sender(config_options = {})
+        config_options = {logger: $null_log}.merge(config_options)
+        subject.new(sdk_key, Config.new(config_options), nil, 0.1)
       end
 
-      def make_sender_with_events_uri(events_uri)
-        subject.new(sdk_key, Config.new(events_uri: events_uri, logger: $null_log, application: {id: "id", version: "version"}), nil, 0.1)
+      def with_sender_and_server(config_options = {})
+        enable_compression = config_options[:compress_events] || false
+        with_server(enable_compression: enable_compression) do |server|
+          config_options[:events_uri] = server.base_uri.to_s
+          yield make_sender(config_options), server
+        end
       end
 
-      def with_sender_and_server
-        with_server do |server|
-          yield make_sender(server), server
+      it "sends analytics event data without compression enabled" do
+        with_sender_and_server(compress_events: false) do |es, server|
+          server.setup_ok_response("/bulk", "")
+
+          result = es.send_event_data(fake_data, "", false)
+
+          expect(result.success).to be true
+          expect(result.must_shutdown).to be false
+          expect(result.time_from_server).not_to be_nil
+
+          req, body = server.await_request_with_body
+          expect(body).to eq fake_data
+          expect(req.header).to include({
+            "authorization" => [ sdk_key ],
+            "content-type" => [ "application/json" ],
+            "user-agent" => [ "RubyClient/" + LaunchDarkly::VERSION ],
+            "x-launchdarkly-event-schema" => [ "4" ],
+            "connection" => [ "Keep-Alive" ],
+          })
+          expect(req.header['x-launchdarkly-payload-id']).not_to eq []
+          expect(req.header['content-encoding']).to eq []
+          expect(req.header['content-length'][0].to_i).to eq fake_data.length
         end
       end
 
-      it "sends analytics event data" do
-        with_sender_and_server do |es, server|
+      it "sends analytics event data with compression enabled" do
+        with_sender_and_server(compress_events: true) do |es, server|
           server.setup_ok_response("/bulk", "")
 
           result = es.send_event_data(fake_data, "", false)
@@ -37,17 +61,18 @@ def with_sender_and_server
           expect(result.must_shutdown).to be false
           expect(result.time_from_server).not_to be_nil
 
-          req = server.await_request
-          expect(req.body).to eq fake_data
+          req, body = server.await_request_with_body
+          expect(body).to eq fake_data
           expect(req.header).to include({
             "authorization" => [ sdk_key ],
+            "content-encoding" => [ "gzip" ],
             "content-type" => [ "application/json" ],
             "user-agent" => [ "RubyClient/" + LaunchDarkly::VERSION ],
             "x-launchdarkly-event-schema" => [ "4" ],
-            "x-launchdarkly-tags" => [ "application-id/id application-version/version" ],
             "connection" => [ "Keep-Alive" ],
           })
           expect(req.header['x-launchdarkly-payload-id']).not_to eq []
+          expect(req.header['content-length'][0].to_i).to be > fake_data.length
         end
       end
 
@@ -63,8 +88,8 @@ def with_sender_and_server
           result = es.send_event_data(fake_data, "", false)
 
           expect(result.success).to be true
-          req = server.await_request
-          expect(req.body).to eq fake_data
+          req, body = server.await_request_with_body
+          expect(body).to eq fake_data
           expect(req.host).to eq "fake-event-server"
         end
       end
@@ -123,7 +148,7 @@ def with_sender_and_server
           begin
             ENV["http_proxy"] = proxy.base_uri.to_s
 
-            es = make_sender_with_events_uri(fake_target_uri)
+            es = make_sender(events_uri: fake_target_uri)
 
             result = es.send_event_data(fake_data, "", false)