ci: new gcc-oldest build to replace gcc-7.3

The minimum GCC version we are required to test is `7.5`. Create a build
name that is more stable and (arguably) easier to grok.

ci/cloudbuild/builds/gcc-oldest.sh

@@ -0,0 +1,38 @@
+#!/bin/bash
+#
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+set -euo pipefail
+
+source "$(dirname "$0")/../../lib/init.sh"
+source module ci/cloudbuild/builds/lib/cmake.sh
+source module ci/cloudbuild/builds/lib/ctest.sh
+source module ci/lib/io.sh
+
+# We run this test in a docker image that includes the oldest GCC that we
+# support.
+export CC=gcc
+export CXX=g++
+
+mapfile -t cmake_args < <(cmake::common_args)
+read -r ENABLED_FEATURES < <(features::always_build_cmake)
+ENABLED_FEATURES="${ENABLED_FEATURES},compute"
+readonly ENABLED_FEATURES
+
+io::run cmake "${cmake_args[@]}" \
+  -DGOOGLE_CLOUD_CPP_ENABLE="${ENABLED_FEATURES}"
+io::run cmake --build cmake-out
+mapfile -t ctest_args < <(ctest::common_args)
+io::run ctest --test-dir cmake-out "${ctest_args[@]}" -LE "integration-test"

ci/cloudbuild/dockerfiles/gcc-oldest.Dockerfile

@@ -0,0 +1,115 @@
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+FROM opensuse/leap:15
+ARG NCPU=4
+
+RUN zypper refresh && \
+    zypper install --allow-downgrade -y automake cmake curl gcc gcc-c++ \
+        git gzip libtool make ninja patch tar wget
+
+
+RUN zypper refresh && \
+    zypper install --allow-downgrade -y abseil-cpp-devel c-ares-devel \
+        libcurl-devel libopenssl-devel libcrc32c-devel nlohmann_json-devel \
+        re2-devel
+
+RUN (echo "/usr/local/lib" ; echo "/usr/local/lib64") | \
+    tee /etc/ld.so.conf.d/usrlocal.conf
+ENV PKG_CONFIG_PATH=/usr/local/lib/pkgconfig:/usr/local/lib64/pkgconfig
+ENV PATH=/usr/local/bin:${PATH}
+
+# Install googletest, remove the downloaded files and the temporary artifacts
+# after a successful build to keep the image smaller (and with fewer layers)
+WORKDIR /var/tmp/build
+RUN curl -fsSL https://github.com/google/googletest/archive/v1.14.0.tar.gz | \
+    tar -xzf - --strip-components=1 && \
+    cmake \
+      -DCMAKE_BUILD_TYPE="Release" \
+      -DBUILD_SHARED_LIBS=yes \
+      -GNinja -S . -B cmake-out && \
+    cmake --build cmake-out && cmake --install cmake-out && \
+    ldconfig && cd /var/tmp && rm -fr build
+
+# Download and compile Google microbenchmark support library:
+WORKDIR /var/tmp/build
+RUN curl -fsSL https://github.com/google/benchmark/archive/v1.8.4.tar.gz | \
+    tar -xzf - --strip-components=1 && \
+    cmake \
+        -DCMAKE_BUILD_TYPE="Release" \
+        -DBUILD_SHARED_LIBS=yes \
+        -DBENCHMARK_ENABLE_TESTING=OFF \
+        -GNinja -S . -B cmake-out && \
+    cmake --build cmake-out && cmake --install cmake-out && \
+    ldconfig && cd /var/tmp && rm -fr build
+
+WORKDIR /var/tmp/build/protobuf
+RUN curl -fsSL https://github.com/protocolbuffers/protobuf/archive/v27.2.tar.gz | \
+    tar -xzf - --strip-components=1 && \
+    cmake \
+        -DCMAKE_BUILD_TYPE=Release \
+        -DBUILD_SHARED_LIBS=yes \
+        -Dprotobuf_BUILD_TESTS=OFF \
+        -Dprotobuf_ABSL_PROVIDER=package \
+        -GNinja -S . -B cmake-out && \
+    cmake --build cmake-out && cmake --install cmake-out && \
+    ldconfig && cd /var/tmp && rm -fr build
+
+# We need to patch opentelemetry-cpp to work around a compiler bug in (at least)
+# GCC 7.x. See https://github.com/open-telemetry/opentelemetry-cpp/issues/1014
+# for more details.
+WORKDIR /var/tmp/build/opentelemetry-cpp
+RUN curl -fsSL https://github.com/open-telemetry/opentelemetry-cpp/archive/v1.16.0.tar.gz | \
+    tar -xzf - --strip-components=1 && \
+    sed -i 's/Stack &GetStack()/Stack \&GetStack() __attribute__((noinline, noclone))/' "api/include/opentelemetry/context/runtime_context.h" && \
+    cmake \
+        -DCMAKE_BUILD_TYPE=Release \
+        -DBUILD_SHARED_LIBS=yes \
+        -DWITH_EXAMPLES=OFF \
+        -DWITH_ABSEIL=ON \
+        -DBUILD_TESTING=OFF \
+        -DOPENTELEMETRY_INSTALL=ON \
+        -DOPENTELEMETRY_ABI_VERSION_NO=2 \
+        -DWITH_DEPRECATED_SDK_FACTORY=OFF \
+        -GNinja -S . -B cmake-out && \
+    cmake --build cmake-out && cmake --install cmake-out && \
+    ldconfig && cd /var/tmp && rm -fr build
+
+WORKDIR /var/tmp/build/grpc
+RUN curl -fsSL https://github.com/grpc/grpc/archive/v1.64.2.tar.gz | \
+    tar -xzf - --strip-components=1 && \
+    cmake \
+        -DCMAKE_BUILD_TYPE=Release \
+        -DBUILD_SHARED_LIBS=yes \
+        -DgRPC_INSTALL=ON \
+        -DgRPC_BUILD_TESTS=OFF \
+        -DgRPC_ABSL_PROVIDER=package \
+        -DgRPC_CARES_PROVIDER=package \
+        -DgRPC_PROTOBUF_PROVIDER=package \
+        -DgRPC_RE2_PROVIDER=package \
+        -DgRPC_SSL_PROVIDER=package \
+        -DgRPC_ZLIB_PROVIDER=package \
+        -GNinja -S . -B cmake-out && \
+    cmake --build cmake-out && cmake --install cmake-out && \
+    ldconfig && cd /var/tmp && rm -fr build
+
+WORKDIR /var/tmp/sccache
+RUN curl -fsSL https://github.com/mozilla/sccache/releases/download/v0.8.1/sccache-v0.8.1-x86_64-unknown-linux-musl.tar.gz | \
+    tar -zxf - --strip-components=1 && \
+    mkdir -p /usr/local/bin && \
+    mv sccache /usr/local/bin/sccache && \
+    chmod +x /usr/local/bin/sccache
+
+# Update the ld.conf cache in case any libraries were installed in /usr/local/lib*
+RUN ldconfig /usr/local/lib*

ci/cloudbuild/triggers/gcc-oldest-ci.yaml

@@ -0,0 +1,28 @@
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+filename: ci/cloudbuild/cloudbuild.yaml
+github:
+  name: google-cloud-cpp
+  owner: googleapis
+  push:
+    branch: ^main$
+includeBuildLogs: INCLUDE_BUILD_LOGS_WITH_STATUS
+name: gcc-oldest-ci
+substitutions:
+  _BUILD_NAME: gcc-oldest
+  _DISTRO: gcc-oldest
+  _TRIGGER_TYPE: ci
+tags:
+- ci

ci/cloudbuild/triggers/gcc-oldest-pr.yaml

@@ -0,0 +1,29 @@
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+filename: ci/cloudbuild/cloudbuild.yaml
+github:
+  name: google-cloud-cpp
+  owner: googleapis
+  pullRequest:
+    branch: ^main$
+    commentControl: COMMENTS_ENABLED_FOR_EXTERNAL_CONTRIBUTORS_ONLY
+includeBuildLogs: INCLUDE_BUILD_LOGS_WITH_STATUS
+name: gcc-oldest-pr
+ substitutions:
+  _BUILD_NAME: gcc-oldest
+  _DISTRO: gcc-oldest
+  _TRIGGER_TYPE: pr
+tags:
+- pr