Create an option to stop ignoring weights. By default weights will still be ignored.

lib/synapse/haproxy.rb

@@ -742,6 +742,14 @@ def generate_backend_stanza(watcher, config)
           b = "\tserver #{backend_name} #{backend['host']}:#{backend['port']}"
           b = "#{b} cookie #{backend_name}" unless config.include?('mode tcp')
           b = "#{b} #{watcher.haproxy['server_options']}" if watcher.haproxy['server_options']
+          if backend.has_key?('weight')
+            # Check if server_options already contains weight, is so log a warning
+            if watcher.haproxy['server_options'].include? 'weight'
+              log.warn "synapse: weight is defined by server_options and by nerve"
+            end
+            weight = backend['weight'].to_i
+            b = "#{b} weight #{weight}"
+          end
           b = "#{b} #{backend['haproxy_server_options']}" if backend['haproxy_server_options']
           b = "#{b} disabled" unless backend['enabled']
           b }

spec/lib/synapse/haproxy_spec.rb

@@ -5,15 +5,18 @@ class MockWatcher; end;
 describe Synapse::Haproxy do
   subject { Synapse::Haproxy.new(config['haproxy']) }
 
-  let(:mockwatcher) do
+  def createmockwatcher(backends)
     mockWatcher = double(Synapse::ServiceWatcher)
     allow(mockWatcher).to receive(:name).and_return('example_service')
-    backends = [{ 'host' => 'somehost', 'port' => 5555}]
     allow(mockWatcher).to receive(:backends).and_return(backends)
     allow(mockWatcher).to receive(:haproxy).and_return({'server_options' => "check inter 2000 rise 3 fall 2"})
     mockWatcher
   end
 
+  let(:mockwatcher) do
+    createmockwatcher [{ 'host' => 'somehost', 'port' => '5555'}]
+  end
+
   let(:mockwatcher_with_server_options) do
     mockWatcher = double(Synapse::ServiceWatcher)
     allow(mockWatcher).to receive(:name).and_return('example_service')
@@ -96,4 +99,24 @@ class MockWatcher; end;
     expect(subject.generate_frontend_stanza(mockwatcher_frontend_with_bind_address, mockConfig)).to eql(["\nfrontend example_service", [], "\tbind 127.0.0.3:2200", "\tdefault_backend example_service"])
   end
 
+  it 'generates backend stanza with weight' do
+    mockConfig = []
+    expect(subject.generate_backend_stanza(createmockwatcher([{ 'weight' => 1, 'host' => 'somehost', 'port' => '5555'}]), mockConfig)).to eql(["\nbackend example_service", [], ["\tserver somehost:5555 somehost:5555 cookie somehost:5555 check inter 2000 rise 3 fall 2 weight 1"]])
+  end
+
+  it 'generates backend stanza with bad weight = 0' do
+    mockConfig = []
+    expect(subject.generate_backend_stanza(createmockwatcher([{ 'weight' => 'hi', 'host' => 'somehost', 'port' => '5555'}]), mockConfig)).to eql(["\nbackend example_service", [], ["\tserver somehost:5555 somehost:5555 cookie somehost:5555 check inter 2000 rise 3 fall 2 weight 0"]])
+  end
+
+  it 'generates backend stanza with nil weight = 0' do
+    mockConfig = []
+    expect(subject.generate_backend_stanza(createmockwatcher([{ 'weight' => nil, 'host' => 'somehost', 'port' => '5555'}]), mockConfig)).to eql(["\nbackend example_service", [], ["\tserver somehost:5555 somehost:5555 cookie somehost:5555 check inter 2000 rise 3 fall 2 weight 0"]])
+  end
+
+  it 'generates backend stanza without weight' do
+    mockConfig = []
+    expect(subject.generate_backend_stanza(createmockwatcher([{ 'host' => 'somehost', 'port' => '5555'}]), mockConfig)).to eql(["\nbackend example_service", [], ["\tserver somehost:5555 somehost:5555 cookie somehost:5555 check inter 2000 rise 3 fall 2"]])
+  end
+
 end

spec/lib/synapse/service_watcher_base_spec.rb

@@ -135,5 +135,37 @@ def remove_arg(name)
         expect(subject.backends).to eq(matching_labeled_backends)
       end
     end
+
+    context 'with weights defined' do
+      let(:backends_with_weight)  { [
+        { 'name' => 'server1', 'host' => 'server1', 'port' => 1111, 'weight' => 11 },
+        { 'name' => 'server2', 'host' => 'server2', 'port' => 2222, 'weight' => 22 },
+      ] }
+      let(:non_matching_weight_backends) { [
+        { 'name' => 'server1', 'host' => 'server1', 'port' => 1111, 'weight' => 33 },
+        { 'name' => 'server2', 'host' => 'server2', 'port' => 2222, 'weight' => 22 },
+      ] }
+      let(:backends_with_non_matching_weight_duplicates) { [
+        { 'name' => 'server1', 'host' => 'server1', 'port' => 1111, 'weight' => 11 },
+        { 'name' => 'server1', 'host' => 'server1', 'port' => 1111, 'weight' => 33 },
+        { 'name' => 'server2', 'host' => 'server2', 'port' => 2222, 'weight' => 22 },
+      ] }
+      it 'updates backends only when weights change' do
+        expect(subject).to receive(:'reconfigure!').exactly(:twice)
+        expect(subject.send(:set_backends, backends_with_weight)).to equal(true)
+        expect(subject.backends).to eq(backends_with_weight)
+        expect(subject.send(:set_backends, non_matching_weight_backends)).to equal(true)
+        expect(subject.backends).to eq(non_matching_weight_backends)
+        expect(subject.send(:set_backends, non_matching_weight_backends)).to equal(false)
+        expect(subject.backends).to eq(non_matching_weight_backends)
+      end
+      it 'ignores duplicates even with non-matching weights' do
+        expect(subject).to receive(:'reconfigure!').exactly(:once)
+        expect(subject.send(:set_backends, backends_with_weight)).to equal(true)
+        expect(subject.backends).to eq(backends_with_weight)
+        expect(subject.send(:set_backends, backends_with_non_matching_weight_duplicates)).to equal(false)
+        expect(subject.backends).to eq(backends_with_weight)
+      end
+    end
   end
 end