[RESOURCE DETECTOR] Add the service resource detector and builder

CHANGELOG.md

@@ -30,6 +30,8 @@ Increment the:
 
 * [RESOURCE DETECTOR] Add the host resource detector
   [#4413](https://github.com/open-telemetry/opentelemetry-cpp/issues/4413)
+* [RESOURCE DETECTOR] Add the service resource detector and builder
+  [#4414](https://github.com/open-telemetry/opentelemetry-cpp/issues/4414)
 * [CONFIGURATION] deprecate config builder cmake components
   [#4428](https://github.com/open-telemetry/opentelemetry-cpp/pull/4428)
 

examples/configuration/kitchen-sink.yaml

@@ -1067,8 +1067,8 @@ resource:
         host:
       - # Enable the process resource detector, which populates process.* attributes.
         process:
-      # - # Enable the service detector, which populates service.name based on the OTEL_SERVICE_NAME environment variable and service.instance.id.
-      #   service:
+      - # Enable the service resource detector, which populates service.name based on the OTEL_SERVICE_NAME environment variable and service.instance.id.
+        service:
       # - # Enable an extension resource detector registered by name.
       #   my_custom_detector:
   # Configure resource schema URL.

examples/configuration/main.cc

@@ -60,6 +60,7 @@
 #  include "opentelemetry/resource_detectors/container_detector_builder.h"
 #  include "opentelemetry/resource_detectors/host_detector_builder.h"
 #  include "opentelemetry/resource_detectors/process_detector_builder.h"
+#  include "opentelemetry/resource_detectors/service_detector_builder.h"
 #endif
 
 static bool opt_help        = false;
@@ -226,6 +227,7 @@ void InitOtel(const std::string &config_file)
     opentelemetry::resource_detector::ContainerDetectorBuilder::Register(registry.get());
     opentelemetry::resource_detector::HostDetectorBuilder::Register(registry.get());
     opentelemetry::resource_detector::ProcessDetectorBuilder::Register(registry.get());
+    opentelemetry::resource_detector::ServiceDetectorBuilder::Register(registry.get());
 #endif
   }
 

install/test/cmake/component_tests/resource_detectors/CMakeLists.txt

@@ -22,6 +22,8 @@ target_link_libraries(
           opentelemetry-cpp::host_resource_detector_builder
           opentelemetry-cpp::process_resource_detector
           opentelemetry-cpp::process_resource_detector_builder
+          opentelemetry-cpp::service_resource_detector
+          opentelemetry-cpp::service_resource_detector_builder
           GTest::gtest
           GTest::gtest_main)
 

install/test/cmake/fetch_content_test/CMakeLists.txt

@@ -112,6 +112,8 @@ target_link_libraries(
           opentelemetry-cpp::host_resource_detector_builder
           opentelemetry-cpp::process_resource_detector
           opentelemetry-cpp::process_resource_detector_builder
+          opentelemetry-cpp::service_resource_detector
+          opentelemetry-cpp::service_resource_detector_builder
           opentelemetry-cpp::http_client
           opentelemetry-cpp::http_client_curl
           opentelemetry-cpp::in_memory_span_exporter

install/test/src/test_resource_detectors.cc

@@ -3,14 +3,21 @@
 
 #include <gtest/gtest.h>
 
+#include <opentelemetry/nostd/variant.h>
 #include <opentelemetry/resource_detectors/container_detector.h>
 #include <opentelemetry/resource_detectors/container_detector_builder.h>
 #include <opentelemetry/resource_detectors/env_entity_detector.h>
 #include <opentelemetry/resource_detectors/host_detector.h>
 #include <opentelemetry/resource_detectors/host_detector_builder.h>
 #include <opentelemetry/resource_detectors/process_detector.h>
 #include <opentelemetry/resource_detectors/process_detector_builder.h>
+#include <opentelemetry/resource_detectors/service_detector.h>
+#include <opentelemetry/resource_detectors/service_detector_builder.h>
+#include <opentelemetry/semconv/service_attributes.h>
 #include <memory>
+#include <string>
+
+namespace semconv = opentelemetry::semconv;
 
 TEST(ResourceDetectorsInstall, ContainerResourceDetector)
 {
@@ -44,6 +51,24 @@ TEST(ResourceDetectorsInstall, ProcessResourceDetector)
   ASSERT_NO_THROW(auto resource = detector->Detect());
 }
 
+TEST(ResourceDetectorsInstall, ServiceResourceDetector)
+{
+  std::unique_ptr<opentelemetry::sdk::resource::ResourceDetector> detector =
+      std::make_unique<opentelemetry::resource_detector::ServiceResourceDetector>();
+  ASSERT_TRUE(detector != nullptr);
+
+  auto resource     = detector->Detect();
+  const auto &attrs = resource.GetAttributes();
+
+  auto name_it = attrs.find(semconv::service::kServiceName);
+  ASSERT_NE(name_it, attrs.end());
+  EXPECT_FALSE(opentelemetry::nostd::get<std::string>(name_it->second).empty());
+
+  auto instance_id_it = attrs.find(semconv::service::kServiceInstanceId);
+  ASSERT_NE(instance_id_it, attrs.end());
+  EXPECT_FALSE(opentelemetry::nostd::get<std::string>(instance_id_it->second).empty());
+}
+
 TEST(ResourceDetectorsInstall, ContainerDetectorBuilder)
 {
   auto builder = std::make_unique<opentelemetry::resource_detector::ContainerDetectorBuilder>();
@@ -73,3 +98,14 @@ TEST(ResourceDetectorsInstall, ProcessDetectorBuilder)
   auto detector = builder->Build(&model);
   ASSERT_TRUE(detector != nullptr);
 }
+
+TEST(ResourceDetectorsInstall, ServiceDetectorBuilder)
+{
+  auto builder = std::make_unique<opentelemetry::resource_detector::ServiceDetectorBuilder>();
+  ASSERT_TRUE(builder != nullptr);
+
+  opentelemetry::sdk::configuration::ServiceResourceDetectorConfiguration model;
+  auto detector = builder->Build(&model);
+  ASSERT_TRUE(detector != nullptr);
+  ASSERT_NO_THROW(auto resource = detector->Detect());
+}

resource_detectors/BUILD

@@ -95,6 +95,43 @@ cc_library(
     ],
 )
 
+cc_library(
+    name = "service_resource_detector_utils",
+    srcs = ["src/service_detector_utils.cc"],
+    copts = ["-fexceptions"],
+    deps = [
+        ":process_resource_detector",
+        "//api",
+        "//resource_detectors:headers",
+        "//sdk:headers",
+        "//sdk/src/common:env_variables",
+        "//sdk/src/common:random",
+        "//sdk/src/resource",
+    ],
+)
+
+cc_library(
+    name = "service_resource_detector",
+    srcs = ["src/service_detector.cc"],
+    copts = ["-fexceptions"],
+    deps = [
+        ":service_resource_detector_utils",
+        "//api",
+        "//resource_detectors:headers",
+        "//sdk:headers",
+        "//sdk/src/resource",
+    ],
+)
+
+cc_library(
+    name = "service_resource_detector_builder",
+    srcs = ["src/service_detector_builder.cc"],
+    deps = [
+        ":service_resource_detector",
+        "//sdk/src/configuration:configuration_core",
+    ],
+)
+
 # Convenience target linking all resource detectors.
 cc_library(
     name = "resource_detectors",
@@ -103,6 +140,7 @@ cc_library(
         ":env_entity_resource_detector",
         ":host_resource_detector",
         ":process_resource_detector",
+        ":service_resource_detector",
     ],
 )
 
@@ -113,5 +151,6 @@ cc_library(
         ":container_resource_detector_builder",
         ":host_resource_detector_builder",
         ":process_resource_detector_builder",
+        ":service_resource_detector_builder",
     ],
 )

resource_detectors/CMakeLists.txt

@@ -136,6 +136,64 @@ target_link_libraries(
   PRIVATE opentelemetry_process_resource_detector
           opentelemetry_configuration_core)
 
+#
+# opentelemetry_service_resource_detector_utils
+#
+
+add_library(opentelemetry_service_resource_detector_utils
+            src/service_detector_utils.cc)
+
+set_target_properties(opentelemetry_service_resource_detector_utils
+                      PROPERTIES EXPORT_NAME service_resource_detector_utils)
+set_target_version(opentelemetry_service_resource_detector_utils)
+
+target_link_libraries(
+  opentelemetry_service_resource_detector_utils
+  PUBLIC opentelemetry_resources
+  PRIVATE opentelemetry_process_resource_detector)
+target_include_directories(
+  opentelemetry_service_resource_detector_utils
+  PUBLIC "$<BUILD_INTERFACE:${CMAKE_CURRENT_LIST_DIR}/include>"
+         "$<INSTALL_INTERFACE:include>")
+
+#
+# opentelemetry_service_resource_detector
+#
+
+add_library(opentelemetry_service_resource_detector src/service_detector.cc)
+
+set_target_properties(opentelemetry_service_resource_detector
+                      PROPERTIES EXPORT_NAME service_resource_detector)
+set_target_version(opentelemetry_service_resource_detector)
+
+target_link_libraries(opentelemetry_service_resource_detector
+                      PUBLIC opentelemetry_service_resource_detector_utils)
+target_include_directories(
+  opentelemetry_service_resource_detector
+  PUBLIC "$<BUILD_INTERFACE:${CMAKE_CURRENT_LIST_DIR}/include>"
+         "$<INSTALL_INTERFACE:include>")
+
+#
+# opentelemetry_service_resource_detector_builder
+#
+
+add_library(opentelemetry_service_resource_detector_builder
+            src/service_detector_builder.cc)
+
+set_target_properties(opentelemetry_service_resource_detector_builder
+                      PROPERTIES EXPORT_NAME service_resource_detector_builder)
+set_target_version(opentelemetry_service_resource_detector_builder)
+
+target_include_directories(
+  opentelemetry_service_resource_detector_builder
+  PUBLIC "$<BUILD_INTERFACE:${CMAKE_CURRENT_LIST_DIR}/include>"
+         "$<INSTALL_INTERFACE:include>")
+
+target_link_libraries(
+  opentelemetry_service_resource_detector_builder
+  PRIVATE opentelemetry_service_resource_detector
+          opentelemetry_configuration_core)
+
 #
 # opentelemetry_resource_detectors (interface to all detectors)
 #
@@ -150,7 +208,8 @@ target_link_libraries(
   INTERFACE opentelemetry_container_resource_detector
             opentelemetry_env_entity_resource_detector
             opentelemetry_host_resource_detector
-            opentelemetry_process_resource_detector)
+            opentelemetry_process_resource_detector
+            opentelemetry_service_resource_detector)
 
 #
 # opentelemetry_resource_detectors_builders (interface to all builders)
@@ -165,7 +224,8 @@ target_link_libraries(
   opentelemetry_resource_detectors_builders
   INTERFACE opentelemetry_container_resource_detector_builder
             opentelemetry_host_resource_detector_builder
-            opentelemetry_process_resource_detector_builder)
+            opentelemetry_process_resource_detector_builder
+            opentelemetry_service_resource_detector_builder)
 
 otel_add_component(
   COMPONENT
@@ -180,6 +240,9 @@ otel_add_component(
   opentelemetry_host_resource_detector_builder
   opentelemetry_process_resource_detector
   opentelemetry_process_resource_detector_builder
+  opentelemetry_service_resource_detector
+  opentelemetry_service_resource_detector_builder
+  opentelemetry_service_resource_detector_utils
   FILES_DIRECTORY
   "include/opentelemetry/"
   FILES_DESTINATION

resource_detectors/README.md

@@ -29,7 +29,25 @@ Contributions to detect more attributes for each Entity are welcome.
 
 [Entity: Service](https://opentelemetry.io/docs/specs/semconv/registry/entities/service/)
 
-Not implemented.
+| Attribute | Description | Linux | macOS | Windows |
+| --- | --- | --- | --- | --- |
+| `service.name` | From `OTEL_SERVICE_NAME` when set | Yes | Yes | Yes |
+| `service.name` | Fallback `unknown_service:<process.executable.name>` or `unknown_service` | Yes | Yes | Yes |
+| `service.instance.id` | Stable RFC 4122 UUID version 4 for the current process | Yes | Yes | Yes |
+
+`service.name` is read only from the `OTEL_SERVICE_NAME` environment variable. When
+that variable is unset, the detector falls back to
+`unknown_service:<process.executable.name>` when the executable name is
+available for the current process, otherwise `unknown_service`.
+
+`service.instance.id` is generated once per process and remains stable until the
+process ID changes (for example after `fork()`).
+
+Limitations:
+
+- The detector does not read `OTEL_RESOURCE_ATTRIBUTES`.
+- Executable-name fallback reuses process detector utilities; on macOS the
+  executable name is available for the current process only.
 
 ### Container Resource Detector
 
@@ -62,10 +80,7 @@ or inaccessible.
 | Attribute | Description | Linux | macOS | Windows |
 | --- | --- | --- | --- | --- |
 | `process.pid` | Process ID | Yes | Yes | Yes |
-| `process.executable.path` | Path via `/proc` (Linux) or Win32 APIs | Yes | No | Yes |
-
-Limitation: current macOS implementation does not populate
-`process.executable.path`.
+| `process.executable.path` | Path via `/proc` (Linux) or Win32 APIs | Yes | Yes | Yes |
 
 ### Env Entity Resource Detector (Experimental)
 
@@ -102,8 +117,7 @@ resource:
       - container:
       - host:
       - process:
-      # NOTE: service detector cannot be configured currently
-      - service: # not implemented (github.com/open-telemetry/opentelemetry-cpp/issues/4414)
+      - service:
 ```
 
 Call `Register` for each builder before creating the SDK:
@@ -112,15 +126,17 @@ Call `Register` for each builder before creating the SDK:
 #include "opentelemetry/resource_detectors/container_detector_builder.h"
 #include "opentelemetry/resource_detectors/host_detector_builder.h"
 #include "opentelemetry/resource_detectors/process_detector_builder.h"
+#include "opentelemetry/resource_detectors/service_detector_builder.h"
 
 opentelemetry::resource_detector::ContainerDetectorBuilder::Register(registry.get());
 opentelemetry::resource_detector::HostDetectorBuilder::Register(registry.get());
 opentelemetry::resource_detector::ProcessDetectorBuilder::Register(registry.get());
+opentelemetry::resource_detector::ServiceDetectorBuilder::Register(registry.get());
 ```
 
 ## Linking with CMake
 
-### Linking to detectors directly (not required for declaritive config)
+### Linking to detectors directly (not required for declarative config)
 
 Link to all available detectors:
 
@@ -136,9 +152,9 @@ find_package(opentelemetry-cpp CONFIG REQUIRED COMPONENTS resource_detectors)
 target_link_libraries(my_target PRIVATE opentelemetry-cpp::host_resource_detector)
 ```
 
-### Linking to builders for declaritive configuration
+### Linking to builders for declarative configuration
 
-Builder targets make detectors available for declaritive configuration and hide
+Builder targets make detectors available for declarative configuration and hide
 the concrete detector implementations.
 
 Link all builders:
@@ -166,12 +182,14 @@ All targets are part of the `resource_detectors` component.
 | `opentelemetry-cpp::resource_detectors` | Interface: links all detectors |
 | `opentelemetry-cpp::resource_detectors_builders` | Interface: links all builders |
 | `opentelemetry-cpp::container_resource_detector` | Container detector |
-| `opentelemetry-cpp::container_resource_detector_builder` | Container detector builder for declaritive configuration |
+| `opentelemetry-cpp::container_resource_detector_builder` | Container detector builder for declarative configuration |
 | `opentelemetry-cpp::env_entity_resource_detector` | Env entity detector |
 | `opentelemetry-cpp::host_resource_detector` | Host detector |
 | `opentelemetry-cpp::host_resource_detector_builder` | Host detector builder for declaritive configuration |
 | `opentelemetry-cpp::process_resource_detector` | Process detector |
-| `opentelemetry-cpp::process_resource_detector_builder` | Process detector builder for declaritive configuration |
+| `opentelemetry-cpp::process_resource_detector_builder` | Process detector builder for declarative configuration |
+| `opentelemetry-cpp::service_resource_detector` | Service detector |
+| `opentelemetry-cpp::service_resource_detector_builder` | Service detector builder for declarative configuration |
 
 ## Linking with Bazel
 
@@ -219,3 +237,5 @@ deps = ["//resource_detectors:process_resource_detector_builder"]
 | `//resource_detectors:host_resource_detector_builder` | Host detector builder |
 | `//resource_detectors:process_resource_detector` | Process detector |
 | `//resource_detectors:process_resource_detector_builder` | Process detector builder |
+| `//resource_detectors:service_resource_detector` | Service detector |
+| `//resource_detectors:service_resource_detector_builder` | Service detector builder |

resource_detectors/include/opentelemetry/resource_detectors/detail/process_detector_utils.h

@@ -26,7 +26,8 @@ std::string FormFilePath(const int32_t &pid, const char *process_type);
  * Platform-specific behavior:
  *   - Windows: Uses OpenProcess() + GetProcessImageFileNameW().
  *   - Linux/Unix: Reads the /proc/<pid>/exe symbolic link.
- *   - TODO: Need to implement for Darwin
+ *   - macOS: Uses _NSGetExecutablePath() for the current process only; returns
+ *     an empty string for other PIDs.
  *
  * @param pid Process ID.
  */