Script to update / verify `repo-infra` when `subtree`ed into other repos

update-subtree-repo-infra.sh

#!/usr/bin/env bash

set -eu
set -o pipefail

readonly upstreamURL="${REPO_INFRA_URL:-git@github.com:kubernetes/repo-infra}"
readonly tempName="temp-repo-infra-${RANDOM}"
readonly repoRoot="$( git rev-parse --show-toplevel )"
readonly targetPath="${REPO_INFRA_PATH:-repo-infra}"

quietGit() {
  local stdout stderr rc
  stdout="$(mktemp)"
  stderr="$(mktemp)"

  set +e
    git "$@" </dev/null >"$stdout" 2>"$stderr"
    rc=$?
  set -e

  [ $rc -ne 0 ] && {
    cat "$stdout"
    cat "$stderr" >&2
  }

  rm -f -- "$stdout" "$stderr"
  return $rc
}

addTempRemote() {
  quietGit remote add "$tempName" "$upstreamURL"
  quietGit fetch "$tempName"
}

forkTempBranch() {
  local oldBranch
  oldBranch="$( git rev-parse --abbrev-ref HEAD )"
  quietGit checkout -b "$tempName"
  echo "$oldBranch"
}

delTempRemote() {
  quietGit remote remove "$tempName"
}

resetForkedBranch() {
  local oldBranch="$1"
  quietGit reset
  quietGit checkout "$oldBranch"
  quietGit branch -D "$tempName"
}

updateRepoInfra() {
  quietGit subtree pull --prefix "$targetPath" "$tempName" master --squash
}

update() {
  cd "$repoRoot"
  trap delTempRemote EXIT

  addTempRemote
  updateRepoInfra
}

verify() {
  local orgRev newRev

  cd "$repoRoot"

  addTempRemote
  trap delTempRemote EXIT

  oldBranch="$( forkTempBranch )"
  trap 'resetForkedBranch "$oldBranch"; delTempRemote' EXIT

  orgRev="$( git rev-parse HEAD )"
  updateRepoInfra
  newRev="$( git rev-parse HEAD )"

  [ "$orgRev" != "$newRev" ] && {
    {
      echo "${targetPath} out of sync with ${upstreamURL}"
      echo
      git diff --stat "$orgRev"
    } >&2
    return 1
  }
}

main() {
  case "$0" in
    *update*) update ;;
    *verify*) verify ;;
    *)        echo 'not allowed' >&2 ; return 254 ;;
  esac
}

main "$@"