entrypoint.sh

#!/bin/sh -l

AUTHOR_FORMAT="%an <%ae>"
AUTHOR_NAME_FORMAT="%an"
AUTHOR_EMAIL_FORMAT="%ae"

COMMITTER_FORMAT="%cn <%ce>"
COMMITTER_NAME_FORMAT="%cn"
COMMITTER_EMAIL_FORMAT="%ce"

COMMIT_SUBJECT="%s"

git_log_format() {
  pattern="$1"
  reference="$2"
  git log -1 --pretty=format:"$pattern" "$reference"
}

{
  echo "GIT_COMMIT_AUTHOR=$(git_log_format "$AUTHOR_FORMAT" "HEAD")"
  echo "GIT_COMMIT_AUTHOR_NAME=$(git_log_format "$AUTHOR_NAME_FORMAT" "HEAD")"
  echo "GIT_COMMIT_AUTHOR_EMAIL=$(git_log_format "$AUTHOR_EMAIL_FORMAT" "HEAD")"
  echo "GIT_COMMIT_COMMITTER=$(git_log_format "$COMMITTER_FORMAT" "HEAD")"
  echo "GIT_COMMIT_COMMITTER_NAME=$(git_log_format "$COMMITTER_NAME_FORMAT" "HEAD")"
  echo "GIT_COMMIT_COMMITTER_EMAIL=$(git_log_format "$COMMITTER_EMAIL_FORMAT" "HEAD")"
  echo "GIT_COMMIT_MESSAGE=$(git_log_format "$COMMIT_SUBJECT" "HEAD")"
} >>"$GITHUB_ENV"