Rehome libcxx-builder docker image & attempt gentler termination. (#71604)

There are three changes present in this PR.

1. Use github packages for libcxx-builder rather than dockerhub.

The ldionne/libcxx-builder image will now be hosted at
ghcr.io/libcxx/libcxx-builder. This has the benefit of allowing members
of the github org to push new versions.

In the future I hope to add github actions to rebuild the image as
needed.

2. Add docker-compose file

The compose file allows to to specify the package repository, so that
users can simply write 'docker compose build' and 'docker compose push'.

It also gives us a centralized place to manage version arguments which
change frequently.

3. Use non-shell CMD form.

This may help the google libcxx builders disconnect more gracefully as
the shell form of CMD may eat the shutdown signal. I'm hoping this
corrects inaccurate agent counts from the buildkite API, since when the
VM's terminate, they do so without signaling it to buildkite, which
hangs around waiting for them to reconnect. It's likely more changes
will be needed though.

---------

Co-authored-by: Mark de Wever <[email protected]>

Author: EricWF

libcxx/utils/ci/Dockerfile

@@ -22,12 +22,11 @@
 # If you're only looking to run the Docker image locally for debugging a
 # build bot, see the `run-buildbot-container` script located in this directory.
 #
-# A pre-built version of this image is maintained on DockerHub as ldionne/libcxx-builder.
-# To update the image, rebuild it and push it to ldionne/libcxx-builder (which
-# will obviously only work if you have permission to do so).
+# A pre-built version of this image is maintained on Github under the libc++ organization, as ghcr.io/libcxx/libcxx-builder.
+# To update the image, rebuild it and push it to github (all members of the libc++ organization should be able to do this).
 #
-#   $ docker build -t ldionne/libcxx-builder libcxx/utils/ci
-#   $ docker push ldionne/libcxx-builder
+#   $ docker compose build
+#   $ docker compose push
 #
 
 FROM ubuntu:jammy
@@ -66,8 +65,8 @@ RUN locale-gen
 # LLVM 15, we still need to have Clang 12 in this Docker image because the LLVM
 # 14 release branch CI uses it. The tip-of-trunk CI will never use Clang 12,
 # though.
-# LLVM POST-BRANCH bump version
-ENV LLVM_HEAD_VERSION=18
+ARG LLVM_HEAD_VERSION # populated in the docker-compose file
+ENV LLVM_HEAD_VERSION=${LLVM_HEAD_VERSION}
 RUN apt-get update && apt-get install -y lsb-release wget software-properties-common
 RUN wget https://apt.llvm.org/llvm.sh -O /tmp/llvm.sh
 RUN bash /tmp/llvm.sh $(($LLVM_HEAD_VERSION - 3)) # for CI transitions
@@ -97,8 +96,9 @@ RUN apt-get update && apt-get install -y llvm-$(($LLVM_HEAD_VERSION - 2))-dev ll
                                                                                                                        libomp5-$LLVM_HEAD_VERSION
 
 # Install the most recent GCC, like clang install the previous version as a transition.
-ENV GCC_LATEST_VERSION=13
 RUN add-apt-repository ppa:ubuntu-toolchain-r/test
+ARG GCC_LATEST_VERSION # populated in the docker-compose file
+ENV GCC_LATEST_VERSION=${GCC_LATEST_VERSION}
 RUN apt-get update && apt install -y gcc-$((GCC_LATEST_VERSION - 1)) g++-$((GCC_LATEST_VERSION - 1))
 RUN apt-get update && apt install -y gcc-$GCC_LATEST_VERSION g++-$GCC_LATEST_VERSION
 
@@ -136,4 +136,4 @@ ENV PATH="${PATH}:/home/libcxx-builder/.buildkite-agent/bin"
 RUN echo "tags=\"queue=libcxx-builders,arch=$(uname -m),os=linux\"" >> "/home/libcxx-builder/.buildkite-agent/buildkite-agent.cfg"
 
 # By default, start the Buildkite agent (this requires a token).
-CMD buildkite-agent start
+CMD ["buildkite-agent", "start"]

libcxx/utils/ci/docker-compose.yml

@@ -0,0 +1,11 @@
+version: '3.7'
+services:
+  libcxx-builder:
+    image: ghcr.io/libcxx/libcxx-builder
+    build:
+      context: .
+      dockerfile: Dockerfile
+      args:
+        GCC_LATEST_VERSION: 13
+        # LLVM POST-BRANCH bump version
+        LLVM_HEAD_VERSION: 18

libcxx/utils/ci/run-buildbot-container

@@ -26,6 +26,6 @@ if [[ ! -d "${MONOREPO_ROOT}/libcxx/utils/ci" ]]; then
     echo "Was unable to find the root of the LLVM monorepo; are you running from within the monorepo?"
     exit 1
 fi
-docker pull ldionne/libcxx-builder
-docker run -it --volume "${MONOREPO_ROOT}:/llvm" --workdir "/llvm" --cap-add=SYS_PTRACE ldionne/libcxx-builder \
+docker pull ghcr.io/libcxx/libcxx-builder
+docker run -it --volume "${MONOREPO_ROOT}:/llvm" --workdir "/llvm" --cap-add=SYS_PTRACE ghcr.io/libcxx/libcxx-builder \
     bash -c 'git config --global --add safe.directory /llvm ; exec bash'

libcxx/utils/ci/vendor/android/Dockerfile

@@ -7,13 +7,13 @@
 #===----------------------------------------------------------------------===##
 
 #
-# This Dockerfile extends ldionne/libcxx-builder with Android support, including
+# This Dockerfile extends ghcr.io/libcxx/libcxx-builder with Android support, including
 # Android Clang and sysroot, Android platform-tools, and the Docker client.
 #
 #   $ docker build -t libcxx-builder-android libcxx/utils/ci/vendor/android
 #
 
-FROM ldionne/libcxx-builder
+FROM ghcr.io/libcxx/libcxx-builder
 
 # Switch back to the root user to install things into /opt and /usr.
 USER root