From 466bf66d8bbe3c193784f7512f34b6e81027c8fa Mon Sep 17 00:00:00 2001
From: Baptiste Foy <baptiste.foy@datadoghq.com>
Date: Thu, 7 Nov 2024 17:58:31 +0100
Subject: [PATCH] fix(options): Don't override c.httpClient if it is set via
 the options

---
 ddtrace/tracer/option.go      | 20 +++++++++++---------
 ddtrace/tracer/option_test.go | 13 +++++++++++++
 2 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/ddtrace/tracer/option.go b/ddtrace/tracer/option.go
index 2e9b08c7cf..4f85dbc71f 100644
--- a/ddtrace/tracer/option.go
+++ b/ddtrace/tracer/option.go
@@ -454,16 +454,18 @@ func newConfig(opts ...StartOption) *config {
 	if c.agentURL == nil {
 		c.agentURL = internal.AgentURLFromEnv()
 	}
-	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.httpClient = udsClient(c.agentURL.Path, c.httpClientTimeout)
-		c.agentURL = &url.URL{
-			Scheme: "http",
-			Host:   fmt.Sprintf("UDS_%s", strings.NewReplacer(":", "_", "/", "_", `\`, "_").Replace(c.agentURL.Path)),
+	if c.httpClient == nil {
+		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.httpClient = udsClient(c.agentURL.Path, c.httpClientTimeout)
+			c.agentURL = &url.URL{
+				Scheme: "http",
+				Host:   fmt.Sprintf("UDS_%s", strings.NewReplacer(":", "_", "/", "_", `\`, "_").Replace(c.agentURL.Path)),
+			}
+		} else {
+			c.httpClient = defaultHTTPClient(c.httpClientTimeout)
 		}
-	} else if c.httpClient == nil {
-		c.httpClient = defaultHTTPClient(c.httpClientTimeout)
 	}
 	WithGlobalTag(ext.RuntimeID, globalconfig.RuntimeID())(c)
 	globalTags := c.globalTags.get()
diff --git a/ddtrace/tracer/option_test.go b/ddtrace/tracer/option_test.go
index 34ebc0a846..078c3ce243 100644
--- a/ddtrace/tracer/option_test.go
+++ b/ddtrace/tracer/option_test.go
@@ -1510,3 +1510,16 @@ func TestWithStatsComputation(t *testing.T) {
 		assert.True(c.statsComputationEnabled)
 	})
 }
+
+func TestNoHTTPClientOverride(t *testing.T) {
+	t.Run("default", func(t *testing.T) {
+		assert := assert.New(t)
+		client := http.DefaultClient
+		client.Timeout = 30 * time.Second // Default is 10s
+		c := newConfig(
+			WithHTTPClient(client),
+			WithUDS("/tmp/agent.sock"),
+		)
+		assert.Equal(30*time.Second, c.httpClient.Timeout)
+	})
+}