ci: automatically bump the version number in rust-lang/gha-self-hosted

.github/workflows/release.yml

@@ -403,3 +403,9 @@ jobs:
         asset_path: ${{ github.workspace }}/linux-arm64-trimmedpackages.json
         asset_name: actions-runner-linux-arm64-${{ steps.releaseNote.outputs.version }}-trimmedpackages.json
         asset_content_type: application/octet-stream
+
+    # Bump the version number in rust-lang/gha-self-hosted
+    - name: Bump the version number in rust-lang/gha-self-hosted
+      run: ./rust-bump-gha-self-hosted.sh
+      env:
+        DEPLOY_KEY: ${{ secrets.DEPLOY_KEY }}

rust-bump-gha-self-hosted.sh

@@ -0,0 +1,47 @@
+#!/bin/bash
+# This script updates the version number in rust-lang/gha-self-hosted after a
+# release is made, removing the need for someone on the infrastructure team to
+# bump the version number manually.
+#
+# It's executed by .github/workflows/release.yml
+
+set -euo pipefail
+IFS=$'\n\t'
+
+repository_url="[email protected]:rust-lang/gha-self-hosted.git"
+version_file="images/ubuntu/files/gha-runner-version"
+
+git_name="rust-lang/gha-runner"
+git_email="[email protected]"
+
+# Load the deploy key on a temporary file.
+key="$(mktemp)"
+trap "rm ${key}" EXIT
+echo "${DEPLOY_KEY}" > "${key}"
+
+# Use the SSH key stored earlier for all git operations, and ignore ssh-agent.
+export GIT_SSH_COMMAND="ssh -i ${key}"
+unset SSH_AUTH_SOCK
+
+# Clone the repository
+clone="$(mktemp -d)"
+trap "rm -rf ${clone}" EXIT
+git clone "${repository_url}" "${clone}"
+
+# Update the version file
+version="$(cat releaseVersion)"
+if [[ "$(cat "${clone}/${version_file}")" = "${version}" ]]; then
+    echo "nothing to update, exiting"
+else
+    echo "${version}" > "${clone}/${version_file}"
+    (
+        cd "${clone}"
+        git add .
+        git \
+            -c commit.gpgsign=false \
+            -c "user.name=${git_name}" \
+            -c "user.email=${git_email}" \
+            commit -m "Bump the GitHub Actions runner to version ${version}"
+        git push
+    )
+fi