[SDK] Support for OTEL_SERVICE_NAME (#2577)

sdk/src/resource/resource_detector.cc

@@ -4,6 +4,7 @@
 #include "opentelemetry/sdk/resource/resource_detector.h"
 #include "opentelemetry/sdk/common/env_variables.h"
 #include "opentelemetry/sdk/resource/resource.h"
+#include "opentelemetry/sdk/resource/semantic_conventions.h"
 
 #include <sstream>
 #include <string>
@@ -15,28 +16,45 @@ namespace resource
 {
 
 const char *OTEL_RESOURCE_ATTRIBUTES = "OTEL_RESOURCE_ATTRIBUTES";
+const char *OTEL_SERVICE_NAME        = "OTEL_SERVICE_NAME";
 
 Resource OTELResourceDetector::Detect() noexcept
 {
-  std::string attributes_str;
-  bool exists;
+  std::string attributes_str, service_name;
 
-  exists = opentelemetry::sdk::common::GetStringEnvironmentVariable(OTEL_RESOURCE_ATTRIBUTES,
-                                                                    attributes_str);
-  if (!exists)
+  bool attributes_exists = opentelemetry::sdk::common::GetStringEnvironmentVariable(
+      OTEL_RESOURCE_ATTRIBUTES, attributes_str);
+  bool service_name_exists =
+      opentelemetry::sdk::common::GetStringEnvironmentVariable(OTEL_SERVICE_NAME, service_name);
+
+  if (!attributes_exists && !service_name_exists)
   {
     return Resource();
   }
+
   ResourceAttributes attributes;
-  std::istringstream iss(attributes_str);
-  std::string token;
-  while (std::getline(iss, token, ','))
+
+  if (attributes_exists)
   {
-    size_t pos        = token.find('=');
-    std::string key   = token.substr(0, pos);
-    std::string value = token.substr(pos + 1);
-    attributes[key]   = value;
+    std::istringstream iss(attributes_str);
+    std::string token;
+    while (std::getline(iss, token, ','))
+    {
+      size_t pos = token.find('=');
+      if (pos != std::string::npos)
+      {
+        std::string key   = token.substr(0, pos);
+        std::string value = token.substr(pos + 1);
+        attributes[key]   = value;
+      }
+    }
   }
+
+  if (service_name_exists)
+  {
+    attributes[SemanticConventions::kServiceName] = service_name;
+  }
+
   return Resource(attributes);
 }
 

sdk/test/resource/resource_test.cc

@@ -220,6 +220,30 @@ TEST(ResourceTest, OtelResourceDetector)
   unsetenv("OTEL_RESOURCE_ATTRIBUTES");
 }
 
+TEST(ResourceTest, OtelResourceDetectorServiceNameOverride)
+{
+  std::map<std::string, std::string> expected_attributes = {{"service.name", "new_name"}};
+
+  setenv("OTEL_RESOURCE_ATTRIBUTES", "service.name=old_name", 1);
+  setenv("OTEL_SERVICE_NAME", "new_name", 1);
+
+  OTELResourceDetector detector;
+  auto resource            = detector.Detect();
+  auto received_attributes = resource.GetAttributes();
+  for (auto &e : received_attributes)
+  {
+    EXPECT_TRUE(expected_attributes.find(e.first) != expected_attributes.end());
+    if (expected_attributes.find(e.first) != expected_attributes.end())
+    {
+      EXPECT_EQ(expected_attributes.find(e.first)->second, nostd::get<std::string>(e.second));
+    }
+  }
+  EXPECT_EQ(received_attributes.size(), expected_attributes.size());
+
+  unsetenv("OTEL_SERVICE_NAME");
+  unsetenv("OTEL_RESOURCE_ATTRIBUTES");
+}
+
 TEST(ResourceTest, OtelResourceDetectorEmptyEnv)
 {
   std::map<std::string, std::string> expected_attributes = {};