infrastructure/roles/gitlab_runner/files/libvirt-executor

#!/usr/bin/env bash
set -o nounset -o errexit -o pipefail
readonly libvirt_pool="images"

ssh() {
  command ssh \
    -i "/run/libvirt-executor/id_ed25519_$(vm_name)" \
    -F /dev/null \
    -o ServerAliveCountMax=2 \
    -o ServerAliveInterval=15 \
    -o UserKnownHostsFile=/dev/null \
    -o StrictHostKeyChecking=off \
    -o LogLevel=error \
    "root@${1}" "${@:2}"
}

vm_name() {
  printf 'runner-%s-project-%d-pipeline-%d-job-%d\n' "${CUSTOM_ENV_CI_RUNNER_SHORT_TOKEN}" "${CUSTOM_ENV_CI_PROJECT_ID}" "${CUSTOM_ENV_CI_PIPELINE_IID}" "${CUSTOM_ENV_CI_JOB_ID}"
}

vm_ip() {
  local ip
  ip="$(virsh -q domifaddr "${1}" | awk -F'[ /]+' '{print $5}')"
  if [[ -n ${ip} ]]; then
    echo "${ip}"
    return 0
  fi
  return 1
}

wait_for_ssh() {
  for _ in {1..30}; do
    if ! ip="$(vm_ip "${1}")"; then
      echo "Waiting for network"
      sleep 1
      continue
    fi
    if ! ssh "${ip}" true; then
      echo "Waiting for SSH to be ready"
      sleep 1
      continue
    fi
    return 0
  done
  echo 'Waited 30 seconds for VM to start, exiting...'
  exit "${SYSTEM_FAILURE_EXIT_CODE:-1}"
}

# https://docs.gitlab.com/runner/executors/custom.html#prepare
prepare() {
  # shellcheck disable=SC2064
  trap "exit ${SYSTEM_FAILURE_EXIT_CODE:-1}" ERR

  if [[ ! -f /usr/local/lib/libvirt-executor/backing-vol-name ]]; then
    echo 'Backing volume not found...'
    exit "${SYSTEM_FAILURE_EXIT_CODE:-1}"
  fi
  local backing_volume
  backing_volume="$(</usr/local/lib/libvirt-executor/backing-vol-name)"

  mkdir -p /run/libvirt-executor
  chmod 700 /run/libvirt-executor
  ssh-keygen -q -N "" -f /run/libvirt-executor/id_ed25519_$(vm_name) -t ed25519

  local ssh_authorized_keys_root
  ssh_authorized_keys_root="$(base64 -w 0 /run/libvirt-executor/id_ed25519_$(vm_name).pub)"

  virsh vol-create-as "${libvirt_pool}" "$(vm_name).qcow2" 0 --format qcow2 --backing-vol "${backing_volume}" --backing-vol-format qcow2
  virsh define <(sed -e "s/\$vm_name/$(vm_name)/" -e "s/\$ssh_authorized_keys_root/${ssh_authorized_keys_root}/" /usr/local/lib/libvirt-executor/domain_template.xml)
  virsh start "$(vm_name)"

  wait_for_ssh "$(vm_name)"
}

# https://docs.gitlab.com/runner/executors/custom.html#run
run() {
  local ip
  ip="$(vm_ip "$(vm_name)")"
  if [[ ${2} == prepare_script ]]; then
    # TODO: Get this fixed upstream or perhaps we should just install inetutils?
    # https://gitlab.com/gitlab-org/gitlab-runner/-/blob/v17.5.2/shells/bash.go?ref_type=tags#L452-L456
    ssh "${ip}" bash < <(sed 's/$(hostname)/$(hostnamectl hostname)/' "${1}") || exit "${BUILD_FAILURE_EXIT_CODE:-1}"
  else
    ssh "${ip}" bash < "${1}" || exit "${BUILD_FAILURE_EXIT_CODE:-1}"
  fi
}

# https://docs.gitlab.com/runner/executors/custom.html#cleanup
cleanup() {
  rm /run/libvirt-executor/id_ed25519_$(vm_name){,.pub}
  virsh destroy "$(vm_name)" || true
  virsh undefine --nvram --remove-all-storage "$(vm_name)"
}

case "${1:-}" in
  prepare)
    prepare
    ;;
  run)
    run "${2}" "${3}"
    ;;
  cleanup)
    cleanup
    ;;
  *)
    echo "Error invalid command: ${1:-}"
    exit 1;
esac