{profiler,ddtrace/tracer}: add UDS client options (#788)

Allow the overriding the HTTP client and transport.
As a convenience, provide an option to create a custom client and
transport that accesses a Unix Domain Socket.

Modified upload tests to exercise both default and custom HTTP clients.

ddtrace/tracer/option.go

@@ -6,6 +6,7 @@
 package tracer
 
 import (
+	"context"
 	"math"
 	"net"
 	"net/http"
@@ -357,6 +358,18 @@ func WithHTTPClient(client *http.Client) StartOption {
 	}
 }
 
+// WithUDS configures the HTTP client to dial the Datadog Agent via the specified Unix Domain Socket path.
+func WithUDS(socketPath string) StartOption {
+	return WithHTTPClient(&http.Client{
+		Transport: &http.Transport{
+			DialContext: func(_ context.Context, _, _ string) (net.Conn, error) {
+				return net.Dial("unix", socketPath)
+			},
+		},
+		Timeout: defaultHTTPTimeout,
+	})
+}
+
 // WithAnalytics allows specifying whether Trace Search & Analytics should be enabled
 // for integrations.
 func WithAnalytics(on bool) StartOption {

ddtrace/tracer/transport_test.go

@@ -212,12 +212,17 @@ func TestTraceCountHeader(t *testing.T) {
 }
 
 type recordingRoundTripper struct {
-	reqs []*http.Request
+	reqs   []*http.Request
+	client *http.Client
+}
+
+func newRecordingRoundTripper(client *http.Client) *recordingRoundTripper {
+	return &recordingRoundTripper{client: client}
 }
 
 func (r *recordingRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
 	r.reqs = append(r.reqs, req)
-	return defaultClient.Transport.RoundTrip(req)
+	return r.client.Transport.RoundTrip(req)
 }
 
 func TestCustomTransport(t *testing.T) {
@@ -233,7 +238,7 @@ func TestCustomTransport(t *testing.T) {
 	assert.Nil(err)
 	assert.NotEmpty(port, "port should be given, as it's chosen randomly")
 
-	customRoundTripper := new(recordingRoundTripper)
+	customRoundTripper := newRecordingRoundTripper(defaultClient)
 	transport := newHTTPTransport(host, &http.Client{Transport: customRoundTripper})
 	p, err := encode(getTestTrace(1, 1))
 	assert.NoError(err)
@@ -253,7 +258,7 @@ func TestWithHTTPClient(t *testing.T) {
 
 	u, err := url.Parse(srv.URL)
 	assert.NoError(err)
-	rt := new(recordingRoundTripper)
+	rt := newRecordingRoundTripper(defaultClient)
 	trc := newTracer(WithAgentAddr(u.Host), WithHTTPClient(&http.Client{Transport: rt}))
 	defer trc.Stop()
 
@@ -264,6 +269,32 @@ func TestWithHTTPClient(t *testing.T) {
 	assert.Len(rt.reqs, 1)
 }
 
+func TestWithUDS(t *testing.T) {
+	os.Setenv("DD_TRACE_STARTUP_LOGS", "0")
+	defer os.Unsetenv("DD_TRACE_STARTUP_LOGS")
+	assert := assert.New(t)
+	udsPath := "/tmp/com.datadoghq.dd-trace-go.tracer.test.sock"
+	unixListener, err := net.Listen("unix", udsPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	srv := &http.Server{Handler: mockDatadogAPIHandler{t: t}}
+	go srv.Serve(unixListener)
+	defer srv.Close()
+
+	dummyCfg := new(config)
+	WithUDS(udsPath)(dummyCfg)
+	rt := newRecordingRoundTripper(dummyCfg.httpClient)
+	trc := newTracer(WithHTTPClient(&http.Client{Transport: rt}))
+	defer trc.Stop()
+
+	p, err := encode(getTestTrace(1, 1))
+	assert.NoError(err)
+	_, err = trc.config.transport.send(p)
+	assert.NoError(err)
+	assert.Len(rt.reqs, 1)
+}
+
 // TestTransportHTTPRace defines a regression tests where the request body was being
 // read even after http.Client.Do returns. See golang/go#33244
 func TestTransportHTTPRace(t *testing.T) {

profiler/options.go

@@ -6,8 +6,10 @@
 package profiler
 
 import (
+	"context"
 	"fmt"
 	"net"
+	"net/http"
 	"net/url"
 	"os"
 	"path/filepath"
@@ -40,12 +42,32 @@ const (
 )
 
 const (
-	defaultAPIURL    = "https://intake.profile.datadoghq.com/v1/input"
-	defaultAgentHost = "localhost"
-	defaultAgentPort = "8126"
-	defaultEnv       = "none"
+	defaultAPIURL      = "https://intake.profile.datadoghq.com/v1/input"
+	defaultAgentHost   = "localhost"
+	defaultAgentPort   = "8126"
+	defaultEnv         = "none"
+	defaultHTTPTimeout = 10 * time.Second // defines the current timeout before giving up with the send process
 )
 
+var defaultClient = &http.Client{
+	// We copy the transport to avoid using the default one, as it might be
+	// augmented with tracing and we don't want these calls to be recorded.
+	// See https://golang.org/pkg/net/http/#DefaultTransport .
+	Transport: &http.Transport{
+		Proxy: http.ProxyFromEnvironment,
+		DialContext: (&net.Dialer{
+			Timeout:   30 * time.Second,
+			KeepAlive: 30 * time.Second,
+			DualStack: true,
+		}).DialContext,
+		MaxIdleConns:          100,
+		IdleConnTimeout:       90 * time.Second,
+		TLSHandshakeTimeout:   10 * time.Second,
+		ExpectContinueTimeout: 1 * time.Second,
+	},
+	Timeout: defaultHTTPTimeout,
+}
+
 var defaultProfileTypes = []ProfileType{CPUProfile, HeapProfile}
 
 type config struct {
@@ -58,6 +80,7 @@ type config struct {
 	service, env  string
 	hostname      string
 	statsd        StatsdClient
+	httpClient    *http.Client
 	tags          []string
 	types         map[ProfileType]struct{}
 	period        time.Duration
@@ -98,6 +121,7 @@ func defaultConfig() *config {
 		apiURL:        defaultAPIURL,
 		service:       filepath.Base(os.Args[0]),
 		statsd:        &statsd.NoOpClient{},
+		httpClient:    defaultClient,
 		period:        DefaultPeriod,
 		cpuDuration:   DefaultDuration,
 		blockRate:     DefaultBlockRate,
@@ -253,3 +277,24 @@ func WithSite(site string) Option {
 		cfg.apiURL = u
 	}
 }
+
+// WithHTTPClient specifies the HTTP client to use when submitting profiles to Site.
+// In general, using this method is only necessary if you have need to customize the
+// transport layer, for instance when using a unix domain socket.
+func WithHTTPClient(client *http.Client) Option {
+	return func(cfg *config) {
+		cfg.httpClient = client
+	}
+}
+
+// WithUDS configures the HTTP client to dial the Datadog Agent via the specified Unix Domain Socket path.
+func WithUDS(socketPath string) Option {
+	return WithHTTPClient(&http.Client{
+		Transport: &http.Transport{
+			DialContext: func(_ context.Context, _, _ string) (net.Conn, error) {
+				return net.Dial("unix", socketPath)
+			},
+		},
+		Timeout: defaultHTTPTimeout,
+	})
+}

profiler/upload.go

@@ -26,10 +26,6 @@ const maxRetries = 2
 var errOldAgent = errors.New("Datadog Agent is not accepting profiles. Agent-based profiling deployments " +
 	"require Datadog Agent >= 7.20")
 
-var httpClient = &http.Client{
-	Timeout: 10 * time.Second,
-}
-
 // backoffDuration calculates the backoff duration given an attempt number and max duration
 func backoffDuration(attempt int, max time.Duration) time.Duration {
 	// https://aws.amazon.com/blogs/architecture/exponential-backoff-and-jitter/
@@ -99,7 +95,7 @@ func (p *profiler) doRequest(bat batch) error {
 	}
 	req.Header.Set("Content-Type", contentType)
 
-	resp, err := httpClient.Do(req)
+	resp, err := p.cfg.httpClient.Do(req)
 	if err != nil {
 		return &retriableError{err}
 	}