[libcxx] Install runner last when building CI containers

[boomanaiden154]

This patch changes when we install the GHA runner in the CI containers. Instead
of having it in the base image, we install it last. This will enable a follow up
patch that will do some setup enabling building the full container image with an
existing base image, thus enabling updating the GHA runner without modifying the
important bits.

[boomanaiden154]

This is a prereq of #148073.

[llvmbot]

@llvm/pr-subscribers-libcxx

Author: Aiden Grossman (boomanaiden154)

Changes

This patch changes when we install the GHA runner in the CI containers. Instead
of having it in the base image, we install it last. This will enable a follow up
patch that will do some setup enabling building the full container image with an
existing base image, thus enabling updating the GHA runner without modifying the
important bits.

---

Full diff: https://github.com/llvm/llvm-project/pull/148072.diff

2 Files Affected:

• (modified) libcxx/utils/ci/Dockerfile (+15-2)
• (modified) libcxx/utils/ci/docker-compose.yml (+2-1)

diff --git a/libcxx/utils/ci/Dockerfile b/libcxx/utils/ci/Dockerfile
index 0a1985b02807b..316e9c7490991 100644
--- a/libcxx/utils/ci/Dockerfile
+++ b/libcxx/utils/ci/Dockerfile
@@ -312,5 +312,18 @@ CMD /opt/android/container-setup.sh && buildkite-agent start
 #
 FROM builder-base AS actions-builder
 
-WORKDIR /home/runner
-USER runner
+ARG GITHUB_RUNNER_VERSION
+
+RUN useradd gha -u 1001 -m -s /bin/bash
+RUN adduser gha sudo
+RUN echo '%sudo ALL=(ALL) NOPASSWD:ALL' >> /etc/sudoers
+WORKDIR /home/gha
+USER gha
+
+ENV RUNNER_MANUALLY_TRAP_SIG=1
+ENV ACTIONS_RUNNER_PRINT_LOG_TO_STDOUT=1
+RUN mkdir actions-runner && \
+    cd actions-runner && \
+    curl -O -L https://github.com/actions/runner/releases/download/v$GITHUB_RUNNER_VERSION/actions-runner-linux-x64-$GITHUB_RUNNER_VERSION.tar.gz && \
+    tar xzf ./actions-runner-linux-x64-$GITHUB_RUNNER_VERSION.tar.gz && \
+    rm ./actions-runner-linux-x64-$GITHUB_RUNNER_VERSION.tar.gz
diff --git a/libcxx/utils/ci/docker-compose.yml b/libcxx/utils/ci/docker-compose.yml
index 2189a41555c2f..20536bc32fa65 100644
--- a/libcxx/utils/ci/docker-compose.yml
+++ b/libcxx/utils/ci/docker-compose.yml
@@ -10,7 +10,8 @@ services:
       dockerfile: Dockerfile
       target: actions-builder
       args:
-        BASE_IMAGE: ghcr.io/actions/actions-runner:2.326.0
+        BASE_IMAGE: ubuntu:jammy
+        GITHUB_RUNNER_VERSION: "2.326.0"
         <<: *compiler_versions
 
   android-buildkite-builder: