feat: mark opentelemetry as required in build files

Author: mpeddada1

.bazelrc

@@ -54,9 +54,6 @@ build --experimental_ui_max_stdouterr_bytes=-1
 # in a random order to help expose undesirable interdependencies.
 test --test_env=GTEST_SHUFFLE --test_env=GTEST_RANDOM_SEED
 
-# By default, build the library with OpenTelemetry
-build --//:enable_opentelemetry
-
 # Don't show warnings when building external dependencies. This still shows
 # warnings when using these dependencies (say in headers).
 build --output_filter='^//((?!(external):).)*$'

BUILD.bazel

@@ -255,7 +255,4 @@ cc_library(
     ],
 )
 
-bool_flag(
-    name = "enable_opentelemetry",
-    build_setting_default = False,
-)
+

bazel/workspace0.bzl

@@ -275,8 +275,7 @@ def gl_cpp_workspace0(name = None):
     )
 
     # Open Telemetry
-    maybe(
-        http_archive,
+    http_archive(
         name = "opentelemetry-cpp",
         urls = [
             "https://github.com/open-telemetry/opentelemetry-cpp/archive/v1.20.0.tar.gz",

cmake/GoogleCloudCppFeatures.cmake

@@ -302,7 +302,7 @@ export_libraries_bzl()
 #   other feature, or even if no features are enabled.
 # ~~~
 macro (google_cloud_cpp_enable_deps)
-    find_package(opentelemetry-cpp CONFIG)
+    list(APPEND GOOGLE_CLOUD_CPP_ENABLE opentelemetry)
     if (__ga_libraries__ IN_LIST GOOGLE_CLOUD_CPP_ENABLE)
         list(APPEND GOOGLE_CLOUD_CPP_ENABLE ${GOOGLE_CLOUD_CPP_GA_LIBRARIES})
         list(APPEND GOOGLE_CLOUD_CPP_ENABLE
@@ -341,11 +341,6 @@ macro (google_cloud_cpp_enable_deps)
     if (asset IN_LIST GOOGLE_CLOUD_CPP_ENABLE)
         list(INSERT GOOGLE_CLOUD_CPP_ENABLE 0 accesscontextmanager osconfig)
     endif ()
-    if (bigtable IN_LIST GOOGLE_CLOUD_CPP_ENABLE)
-        if (opentelemetry-cpp_FOUND)
-            list(INSERT GOOGLE_CLOUD_CPP_ENABLE 0 opentelemetry)
-        endif ()
-    endif ()
     if (contentwarehouse IN_LIST GOOGLE_CLOUD_CPP_ENABLE)
         list(INSERT GOOGLE_CLOUD_CPP_ENABLE 0 documentai)
     endif ()
@@ -360,9 +355,6 @@ macro (google_cloud_cpp_enable_deps)
         OR (experimental-storage_grpc IN_LIST GOOGLE_CLOUD_CPP_ENABLE))
         list(INSERT GOOGLE_CLOUD_CPP_ENABLE 0 storage)
     endif ()
-    if (opentelemetry IN_LIST GOOGLE_CLOUD_CPP_ENABLE)
-        list(INSERT GOOGLE_CLOUD_CPP_ENABLE 0 monitoring trace opentelemetry)
-    endif ()
 endmacro ()
 
 # Cleanup the "GOOGLE_CLOUD_CPP_ENABLE" variable. Remove duplicates, and set

google/cloud/BUILD.bazel

@@ -44,13 +44,6 @@ capture_build_info(
     ],
 )
 
-config_setting(
-    name = "enable_opentelemetry",
-    flag_values = {
-        "//:enable_opentelemetry": "true",
-    },
-)
-
 filegroup(
     name = "common_hdrs",
     srcs = [h for h in google_cloud_cpp_common_hdrs if not h.startswith("internal/")],
@@ -61,13 +54,10 @@ cc_library(
     name = "google_cloud_cpp_common_private",
     srcs = google_cloud_cpp_common_srcs + ["internal/build_info.cc"],
     hdrs = google_cloud_cpp_common_hdrs,
-    defines = select({
-        ":enable_opentelemetry": [
-            # Enable OpenTelemetry features in google-cloud-cpp
-            "GOOGLE_CLOUD_CPP_HAVE_OPENTELEMETRY",
-        ],
-        "//conditions:default": [],
-    }),
+    defines = [
+        # Enable OpenTelemetry features in google-cloud-cpp
+        "GOOGLE_CLOUD_CPP_HAVE_OPENTELEMETRY",
+    ],
     linkopts = select({
         "@platforms//os:windows": [
             "-DEFAULTLIB:bcrypt.lib",
@@ -94,12 +84,8 @@ cc_library(
         "@abseil-cpp//absl/types:optional",
         "@abseil-cpp//absl/types:span",
         "@abseil-cpp//absl/types:variant",
+        "@opentelemetry-cpp//api",
     ] + select({
-        ":enable_opentelemetry": [
-            "@opentelemetry-cpp//api",
-        ],
-        "//conditions:default": [],
-    }) + select({
         "@platforms//os:windows": [],
         "//conditions:default": [
             "@boringssl//:crypto",

google/cloud/bigtable/CMakeLists.txt

@@ -47,7 +47,7 @@ include(CTest)
 # Export the version information for Bazel.
 include(CreateBazelConfig)
 
-find_package(opentelemetry-cpp CONFIG)
+find_package(opentelemetry-cpp CONFIG REQUIRED)
 
 # the client library
 add_library(
@@ -299,14 +299,12 @@ target_link_libraries(
            gRPC::grpc++
            gRPC::grpc
            protobuf::libprotobuf)
-if (opentelemetry-cpp_FOUND)
-    target_compile_definitions(
-        google_cloud_cpp_bigtable
-        PRIVATE GOOGLE_CLOUD_CPP_BIGTABLE_WITH_OTEL_METRICS)
-    target_link_libraries(google_cloud_cpp_bigtable
-                          PUBLIC google-cloud-cpp::opentelemetry)
-    set(EXTRA_MODULES "google_cloud_cpp_opentelemetry" "opentelemetry_metrics")
-endif ()
+target_compile_definitions(
+    google_cloud_cpp_bigtable
+    PRIVATE GOOGLE_CLOUD_CPP_BIGTABLE_WITH_OTEL_METRICS)
+target_link_libraries(google_cloud_cpp_bigtable
+                      PUBLIC google-cloud-cpp::opentelemetry)
+set(EXTRA_MODULES "google_cloud_cpp_opentelemetry" "opentelemetry_metrics")
 google_cloud_cpp_add_common_options(google_cloud_cpp_bigtable)
 target_include_directories(
     google_cloud_cpp_bigtable

google/cloud/testing_util/BUILD.bazel

@@ -44,13 +44,9 @@ cc_library(
         "@abseil-cpp//absl/debugging:failure_signal_handler",
         "@abseil-cpp//absl/debugging:symbolize",
         "@googletest//:gtest_main",
-    ] + select({
-        "//google/cloud:enable_opentelemetry": [
             "@opentelemetry-cpp//exporters/memory:in_memory_span_exporter",
             "@opentelemetry-cpp//sdk/src/trace",
-        ],
-        "//conditions:default": [],
-    }),
+        ]
 )
 
 cc_library(

google/cloud/testing_util/CMakeLists.txt

@@ -58,13 +58,10 @@ add_library(
 target_link_libraries(
     google_cloud_cpp_testing
     PUBLIC absl::symbolize absl::failure_signal_handler
-           google-cloud-cpp::common GTest::gmock)
-if (opentelemetry-cpp_FOUND)
-    target_link_libraries(
-        google_cloud_cpp_testing
-        PRIVATE opentelemetry-cpp::in_memory_span_exporter
-                opentelemetry-cpp::trace)
-endif ()
+           google-cloud-cpp::common GTest::gmock
+    PRIVATE opentelemetry-cpp::in_memory_span_exporter
+            opentelemetry-cpp::trace)
+
 google_cloud_cpp_add_common_options(google_cloud_cpp_testing)
 
 include(CheckCXXSymbolExists)