ddtrace/tracer: put hostname detection behind a compat environment va…

…riable (#2786)
DataDog · Jul 16, 2024 · 1c67ac3 · 1c67ac3
1 parent d3a6549
commit 1c67ac3
Show file tree

Hide file tree

Showing 3 changed files with 11 additions and 11 deletions.
diff --git a/ddtrace/tracer/option.go b/ddtrace/tracer/option.go
@@ -22,6 +22,7 @@ import (
 	"strings"
 	"time"
 
+	"golang.org/x/mod/semver"
 	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace"
 	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/ext"
 	"gopkg.in/DataDog/dd-trace-go.v1/internal"
@@ -384,7 +385,13 @@ func newConfig(opts ...StartOption) *config {
 	}
 	c.profilerEndpoints = internal.BoolEnv(traceprof.EndpointEnvVar, true)
 	c.profilerHotspots = internal.BoolEnv(traceprof.CodeHotspotsEnvVar, true)
-	c.enableHostnameDetection = internal.BoolEnv("DD_CLIENT_HOSTNAME_ENABLED", true)
+	if compatMode := os.Getenv("DD_TRACE_CLIENT_HOSTNAME_COMPAT"); compatMode != "" {
+		if semver.IsValid(compatMode) {
+			c.enableHostnameDetection = semver.Compare(semver.MajorMinor(compatMode), "v1.66") <= 0
+		} else {
+			log.Warn("ignoring DD_TRACE_CLIENT_HOSTNAME_COMPAT, invalid version %q", compatMode)
+		}
+	}
 	c.debugAbandonedSpans = internal.BoolEnv("DD_TRACE_DEBUG_ABANDONED_SPANS", false)
 	if c.debugAbandonedSpans {
 		c.spanTimeout = internal.DurationEnv("DD_TRACE_ABANDONED_SPAN_TIMEOUT", 10*time.Minute)
@@ -438,7 +445,6 @@ func newConfig(opts ...StartOption) *config {
 	if c.agentURL.Scheme == "unix" {
 		// If we're connecting over UDS we can just rely on the agent to provide the hostname
 		log.Debug("connecting to agent over unix, do not set hostname on any traces")
-		c.enableHostnameDetection = false
 		c.httpClient = udsClient(c.agentURL.Path, c.httpClientTimeout)
 		c.agentURL = &url.URL{
 			Scheme: "http",

diff --git a/ddtrace/tracer/option_test.go b/ddtrace/tracer/option_test.go
@@ -1438,20 +1438,15 @@ func TestWithHeaderTags(t *testing.T) {
 }
 
 func TestHostnameDisabled(t *testing.T) {
-	t.Run("DisabledWithUDS", func(t *testing.T) {
-		t.Setenv("DD_TRACE_AGENT_URL", "unix://somefakesocket")
+	t.Run("Default", func(t *testing.T) {
 		c := newConfig()
 		assert.False(t, c.enableHostnameDetection)
 	})
-	t.Run("Default", func(t *testing.T) {
+	t.Run("EnableViaEnv", func(t *testing.T) {
+		t.Setenv("DD_TRACE_CLIENT_HOSTNAME_COMPAT", "v1.66")
 		c := newConfig()
 		assert.True(t, c.enableHostnameDetection)
 	})
-	t.Run("DisableViaEnv", func(t *testing.T) {
-		t.Setenv("DD_CLIENT_HOSTNAME_ENABLED", "false")
-		c := newConfig()
-		assert.False(t, c.enableHostnameDetection)
-	})
 }
 
 func TestPartialFlushing(t *testing.T) {

diff --git a/ddtrace/tracer/span_test.go b/ddtrace/tracer/span_test.go
@@ -590,7 +590,6 @@ func TestSpanProfilingTags(t *testing.T) {
 }
 
 func TestSpanError(t *testing.T) {
-	t.Setenv("DD_CLIENT_HOSTNAME_ENABLED", "false") // the host name is inconsistently returning a value, causing the test to flake.
 	assert := assert.New(t)
 	tracer := newTracer(withTransport(newDefaultTransport()))
 	internal.SetGlobalTracer(tracer)