Migrate jaeger-agent implementation from internal repository

.gitignore

@@ -11,3 +11,4 @@ _site/
 env/
 Gemfile.lock
 vendor/
+examples/hotrod/hotrod

Makefile

@@ -60,7 +60,7 @@ fmt:
 lint:
 	$(GOVET) $(PACKAGES)
 	@cat /dev/null > $(LINT_LOG)
-	@$(foreach pkg, $(PACKAGES), $(GOLINT) $(pkg) | grep -v thrift-gen >> $(LINT_LOG) || true;)
+	@$(foreach pkg, $(PACKAGES), $(GOLINT) $(pkg) | grep -v -e thrift-gen -e thrift-0.9.2 >> $(LINT_LOG) || true;)
 	@[ ! -s "$(LINT_LOG)" ] || (echo "Lint Failures" | cat - $(LINT_LOG) && false)
 	@$(GOFMT) -e -s -l $(ALL_SRC) > $(FMT_LOG)
 	@./scripts/updateLicenses.sh >> $(FMT_LOG)

cmd/agent/README.md

@@ -0,0 +1,35 @@
+# Jaeger Agent
+
+`jaeger-agent` is a daemon program that runs on every host and receives
+tracing information submitted by applications via Jaeger client 
+libraries.
+
+## Structure
+
+* Agent
+    * processor as ThriftProcessor
+        * server as TBufferedServer
+            * Thrift UDP Transport
+        * reporter as TCollectorReporter
+    * sampling server
+        * sampling manager as sampling.TCollectorProxy
+
+### UDP Server
+
+Listens on UDP transport, reads data as `[]byte` and forwards to
+`processor` over channel. Processor has N workers that read from
+the channel, convert to thrift-generated object model, and pass on
+to the Reporter. `TCollectorReporter` submits the spans to remote
+`tcollector` service.
+
+### Sampling Server
+
+An HTTP server handling request in the form
+
+    http://localhost:port/sampling?service=xxxx`
+
+Delegates to `sampling.Manager` to get the sampling strategy.
+`sampling.TCollectorProxy` implements `sampling.Manager` by querying
+remote `tcollector` service. Then the server converts
+thrift response from sampling manager into JSON and responds to clients.
+

cmd/agent/app/agent.go

@@ -0,0 +1,83 @@
+// Copyright (c) 2017 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package app
+
+import (
+	"io"
+	"net"
+	"net/http"
+
+	"github.com/uber-go/zap"
+
+	"github.com/uber/jaeger/cmd/agent/app/processors"
+)
+
+// Agent is a composition of all services / components
+type Agent struct {
+	processors      []processors.Processor
+	samplingServer  *http.Server
+	discoveryClient interface{}
+	logger          zap.Logger
+	closer          io.Closer
+}
+
+// NewAgent creates the new Agent.
+func NewAgent(
+	processors []processors.Processor,
+	samplingServer *http.Server,
+	discoveryClient interface{},
+	logger zap.Logger,
+) *Agent {
+	return &Agent{
+		processors:      processors,
+		samplingServer:  samplingServer,
+		discoveryClient: discoveryClient,
+		logger:          logger,
+	}
+}
+
+// Run runs all of agent UDP and HTTP servers in separate go-routines.
+// It returns an error when it's immediately apparent on startup, but
+// any errors happening after starting the servers are only logged.
+func (a *Agent) Run() error {
+	listener, err := net.Listen("tcp", a.samplingServer.Addr)
+	if err != nil {
+		return err
+	}
+	a.closer = listener
+	go func() {
+		if err := a.samplingServer.Serve(listener); err != nil {
+			a.logger.Error("sampling server failure", zap.Error(err))
+		}
+	}()
+	for _, processor := range a.processors {
+		go processor.Serve()
+	}
+	return nil
+}
+
+// Stop forces all agent go routines to exit.
+func (a *Agent) Stop() {
+	for _, processor := range a.processors {
+		go processor.Stop()
+	}
+	a.closer.Close()
+}

cmd/agent/app/agent_test.go

@@ -0,0 +1,93 @@
+// Copyright (c) 2017 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package app
+
+import (
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"github.com/uber-go/zap"
+	"github.com/uber/jaeger-lib/metrics"
+)
+
+func TestAgentStartError(t *testing.T) {
+	cfg := &Builder{}
+	agent, err := cfg.CreateAgent(metrics.NullFactory, zap.New(zap.NullEncoder()))
+	require.NoError(t, err)
+	agent.samplingServer.Addr = "bad-address"
+	assert.Error(t, agent.Run())
+}
+
+func TestAgentStartStop(t *testing.T) {
+	cfg := Builder{
+		Processors: []ProcessorConfiguration{
+			{
+				Model:    jaegerModel,
+				Protocol: compactProtocol,
+				Server: ServerConfiguration{
+					HostPort: "127.0.0.1:0",
+				},
+			},
+		},
+	}
+	agent, err := cfg.CreateAgent(metrics.NullFactory, zap.New(zap.NullEncoder()))
+	require.NoError(t, err)
+	ch := make(chan error, 2)
+	go func() {
+		if err := agent.Run(); err != nil {
+			t.Errorf("error from agent.Run(): %s", err)
+			ch <- err
+		}
+		close(ch)
+	}()
+
+	url := fmt.Sprintf("http://%s/sampling?service=abc", agent.samplingServer.Addr)
+	httpClient := &http.Client{
+		Timeout: 100 * time.Millisecond,
+	}
+	for i := 0; i < 1000; i++ {
+		_, err := httpClient.Get(url)
+		if err == nil {
+			break
+		}
+		select {
+		case err := <-ch:
+			if err != nil {
+				t.Fatalf("error from agent: %s", err)
+			}
+			break
+		default:
+			time.Sleep(time.Millisecond)
+		}
+	}
+	resp, err := http.Get(url)
+	require.NoError(t, err)
+	body, err := ioutil.ReadAll(resp.Body)
+	assert.NoError(t, err)
+	assert.Equal(t, "tcollector error: no peers available\n", string(body))
+	agent.Stop()
+	assert.NoError(t, <-ch)
+}