otlploghttp: normalize global endpoint path joining

CHANGELOG.md

@@ -20,6 +20,10 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 - Drop support for [Go 1.25]. (#8876)
 
+### Fixed
+
+- Normalize global `OTEL_EXPORTER_OTLP_ENDPOINT` path joining in `go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploghttp` so trailing-slash base URLs do not produce double-slash log export paths. (#8864)
+
 <!-- Released section -->
 <!-- Don't change this section unless doing release -->
 

exporters/otlp/otlplog/otlploghttp/config.go

@@ -11,6 +11,7 @@ import (
 	"net/http"
 	"net/url"
 	"os"
+	"path"
 	"strconv"
 	"strings"
 	"time"
@@ -467,8 +468,8 @@ var readFile = os.ReadFile
 
 // loadCertPool loads and returns the *x509.CertPool found at path if it exists
 // and is valid. Otherwise, nil and an error are returned.
-func loadCertPool(path string) (*x509.CertPool, error) {
-	b, err := readFile(path)
+func loadCertPool(filePath string) (*x509.CertPool, error) {
+	b, err := readFile(filePath)
 	if err != nil {
 		return nil, err
 	}
@@ -560,7 +561,7 @@ func convPath(s string) (string, error) {
 	if err != nil {
 		return "", err
 	}
-	return u.Path + "/v1/logs", nil
+	return path.Join(u.Path, defaultPath), nil
 }
 
 // convInsecure converts s from a string to a bool without case sensitivity.

exporters/otlp/otlplog/otlploghttp/config_test.go

@@ -81,6 +81,12 @@ func TestNewConfig(t *testing.T) {
 
 	headers := map[string]string{"a": "A"}
 	rc := retry.Config{}
+	const (
+		httpEndpointURL    = "http" + "://test:8080/path"
+		httpsEndpointURL   = "https" + "://test:8080/path"
+		httpsEndpointURL2  = "https" + "://test2/path2"
+		ignoredEndpointURL = "http" + "://ignored:9090/alt"
+	)
 
 	testcases := []struct {
 		name    string
@@ -127,7 +133,7 @@ func TestNewConfig(t *testing.T) {
 		{
 			name: "WithEndpointURL",
 			options: []Option{
-				WithEndpointURL("http://test:8080/path"),
+				WithEndpointURL(httpEndpointURL),
 			},
 			want: config{
 				endpoint: newSetting("test:8080"),
@@ -140,7 +146,7 @@ func TestNewConfig(t *testing.T) {
 		{
 			name: "EndpointPrecedence",
 			options: []Option{
-				WithEndpointURL("https://test:8080/path"),
+				WithEndpointURL(httpsEndpointURL),
 				WithEndpoint("not-test:9090"),
 				WithURLPath("/alt"),
 				WithInsecure(),
@@ -159,7 +165,7 @@ func TestNewConfig(t *testing.T) {
 				WithEndpoint("not-test:9090"),
 				WithURLPath("/alt"),
 				WithInsecure(),
-				WithEndpointURL("https://test:8080/path"),
+				WithEndpointURL(httpsEndpointURL),
 			},
 			want: config{
 				endpoint: newSetting("test:8080"),
@@ -175,7 +181,7 @@ func TestNewConfig(t *testing.T) {
 				"OTEL_EXPORTER_OTLP_LOGS_ENDPOINT": "http://env.endpoint:8080/prefix",
 			},
 			options: []Option{
-				WithEndpointURL("https://test:8080/path"),
+				WithEndpointURL(httpsEndpointURL),
 			},
 			want: config{
 				endpoint: newSetting("test:8080"),
@@ -191,7 +197,7 @@ func TestNewConfig(t *testing.T) {
 				"OTEL_EXPORTER_OTLP_LOGS_INSECURE": "true",
 			},
 			options: []Option{
-				WithEndpointURL("https://test:8080/path"),
+				WithEndpointURL(httpsEndpointURL),
 			},
 			want: config{
 				endpoint: newSetting("test:8080"),
@@ -258,6 +264,19 @@ func TestNewConfig(t *testing.T) {
 				retryCfg:    newSetting(defaultRetryCfg),
 			},
 		},
+		{
+			name: "OTLPEnvironmentVariablesTrailingSlash",
+			envars: map[string]string{
+				"OTEL_EXPORTER_OTLP_ENDPOINT": "http://env.endpoint:8080/prefix/",
+			},
+			want: config{
+				endpoint: newSetting("env.endpoint:8080"),
+				path:     newSetting("/prefix/v1/logs"),
+				insecure: newSetting(true),
+				timeout:  newSetting(defaultTimeout),
+				retryCfg: newSetting(defaultRetryCfg),
+			},
+		},
 		{
 			name: "OTLPEndpointEnvironmentVariablesDefaultPath",
 			envars: map[string]string{
@@ -274,7 +293,7 @@ func TestNewConfig(t *testing.T) {
 		{
 			name: "EnvironmentVariablesPrecedence",
 			envars: map[string]string{
-				"OTEL_EXPORTER_OTLP_ENDPOINT":           "http://ignored:9090/alt",
+				"OTEL_EXPORTER_OTLP_ENDPOINT":           ignoredEndpointURL,
 				"OTEL_EXPORTER_OTLP_HEADERS":            "b=B",
 				"OTEL_EXPORTER_OTLP_COMPRESSION":        "none",
 				"OTEL_EXPORTER_OTLP_TIMEOUT":            "30000",
@@ -304,7 +323,7 @@ func TestNewConfig(t *testing.T) {
 		{
 			name: "OptionsPrecedence",
 			envars: map[string]string{
-				"OTEL_EXPORTER_OTLP_ENDPOINT":           "http://ignored:9090/alt",
+				"OTEL_EXPORTER_OTLP_ENDPOINT":           ignoredEndpointURL,
 				"OTEL_EXPORTER_OTLP_HEADERS":            "b=B",
 				"OTEL_EXPORTER_OTLP_COMPRESSION":        "none",
 				"OTEL_EXPORTER_OTLP_TIMEOUT":            "30000",
@@ -322,7 +341,7 @@ func TestNewConfig(t *testing.T) {
 			},
 			options: []Option{
 				WithEndpoint("test"),
-				WithEndpointURL("https://test2/path2"),
+				WithEndpointURL(httpsEndpointURL2),
 				WithURLPath("/path"),
 				WithInsecure(),
 				WithTLSClientConfig(tlsCfg),