feat: allow payload compression in POST requests

- only done if custom_http_headers config includes {'Content-Encoding' => 'gzip'}
- only allow gzip.
- 'Content-Encoding' header will get dropped in GET requests.
- undocumented feature.

lib/unleash/util/http.rb

@@ -1,5 +1,7 @@
 require 'net/http'
 require 'uri'
+require 'zlib'
+require 'stringio'
 
 module Unleash
   module Util
@@ -8,6 +10,7 @@ def self.get(uri, etag = nil, headers_override = nil)
         http = http_connection(uri)
 
         request = Net::HTTP::Get.new(uri.request_uri, http_headers(etag, headers_override))
+        request.delete('Content-Encoding')
 
         http.request(request)
       end
@@ -16,7 +19,15 @@ def self.post(uri, body)
         http = http_connection(uri)
 
         request = Net::HTTP::Post.new(uri.request_uri, http_headers)
-        request.body = body
+        request_body =
+          if request['Content-Encoding'] == 'gzip'
+            request_body_writer = Zlib::GzipWriter.new(StringIO.new)
+            request_body_writer << body
+            request_body_writer.close.string
+          else
+            body
+          end
+        request.body = request_body
 
         http.request(request)
       end
@@ -32,6 +43,7 @@ def self.http_connection(uri)
 
       # @param etag [String, nil]
       # @param headers_override [Hash, nil]
+      # @return [Hash]
       def self.http_headers(etag = nil, headers_override = nil)
         Unleash.logger.debug "ETag: #{etag}" unless etag.nil?
 

spec/unleash/client_spec.rb

@@ -1,3 +1,6 @@
+require 'stringio'
+require 'zlib'
+
 RSpec.describe Unleash::Client do
   after do
     WebMock.reset!
@@ -108,6 +111,107 @@
     ).to have_been_made.once
   end
 
+  it "The compress http header compresses post requests when initializing client" do
+    WebMock.stub_request(:post, "http://test-url/client/register")
+      .with(
+        headers: {
+          'Accept' => '*/*',
+          'Content-Type' => 'application/json',
+          'Content-Encoding' => 'gzip',
+          'Accept-Encoding' => 'gzip;q=1.0,deflate;q=0.6,identity;q=0.3',
+          'User-Agent' => 'Ruby',
+          'X-Api-Key' => '123'
+        }
+      )
+      .to_return(status: 200, body: "", headers: {})
+    WebMock.stub_request(:post, "http://test-url/client/metrics")
+      .with(
+        headers: {
+          'Accept' => '*/*',
+          'Accept-Encoding' => 'gzip;q=1.0,deflate;q=0.6,identity;q=0.3',
+          'Content-Type' => 'application/json',
+          'Content-Encoding' => 'gzip',
+          'User-Agent' => 'Ruby'
+        }
+      )
+      .to_return(status: 200, body: "", headers: {})
+
+    simple_features = {
+      "version": 1,
+      "features": [
+        {
+          "name": "Feature.A",
+          "description": "Enabled toggle",
+          "enabled": true,
+          "strategies": [{ "name": "default" }]
+        }
+      ]
+    }
+    WebMock.stub_request(:get, "http://test-url/client/features")
+      .with(
+        headers: {
+          'Accept' => '*/*',
+          'Accept-Encoding' => 'gzip;q=1.0,deflate;q=0.6,identity;q=0.3',
+          'Content-Type' => 'application/json',
+          'Unleash-Appname' => 'my-test-app',
+          'Unleash-Instanceid' => 'rspec/test',
+          'User-Agent' => 'Ruby',
+          'X-Api-Key' => '123'
+        }
+      )
+      .to_return(status: 200, body: simple_features.to_json, headers: {})
+
+    unleash_client = Unleash::Client.new(
+      url: 'http://test-url/',
+      app_name: 'my-test-app',
+      instance_id: 'rspec/test',
+      custom_http_headers: { 'X-API-KEY' => '123', 'Content-Encoding' => 'gzip' }
+    )
+
+    expect(unleash_client).to be_a(Unleash::Client)
+
+    expect(
+      a_request(:post, "http://test-url/client/register")
+        .with(headers: {
+          'Content-Type': 'application/json',
+          'Content-Encoding': 'gzip',
+          'X-API-KEY': '123',
+          'UNLEASH-APPNAME': 'my-test-app',
+          'UNLEASH-INSTANCEID': 'rspec/test'
+        })
+    ).to have_been_made.once
+
+    expect(
+      a_request(:get, "http://test-url/client/features")
+        .with(headers: {
+          'Content-Type': 'application/json',
+          'X-API-KEY': '123',
+          'UNLEASH-APPNAME': 'my-test-app',
+          'UNLEASH-INSTANCEID': 'rspec/test'
+        })
+    ).to have_been_made.once
+
+    # Test now sending of metrics
+    # Sending metrics, if they have been evaluated:
+    unleash_client.is_enabled?("Feature.A")
+    unleash_client.get_variant("Feature.A")
+    Unleash.reporter.post
+    expect(
+      a_request(:post, "http://test-url/client/metrics")
+        .with(headers: {
+          'Content-Type': 'application/json',
+          'Content-Encoding': 'gzip',
+          'X-API-KEY': '123',
+          'UNLEASH-APPNAME': 'my-test-app',
+          'UNLEASH-INSTANCEID': 'rspec/test'
+        })
+        .with do |request|
+          uncompressed_request_body = Zlib::GzipReader.wrap(StringIO.new(request.body), &:read)
+          JSON.parse(uncompressed_request_body)['bucket']['toggles']['Feature.A']['yes'] == 2
+        end
+    ).to have_been_made.once
+  end
+
   it "should load/use correct variants from the unleash server" do
     WebMock.stub_request(:post, "http://test-url/client/register")
       .with(