Merge master script

merge-master.sh

#!/bin/bash

# Example of the slack-usernames file:
# han.solo@gitlab.com @UABCDEF123

# Fail script if any command fails
set -e

GITLAB_HOST=${GITLAB_HOST:-gitlab.com}
GITLAB_UPSTREAM_NAMESPACE=${GITLAB_UPSTREAM_NAMESPACE:-mycorpcompany}
TOOLS_DIR=$(dirname "$0")
NEWLINE=$'\n'

function usage {
  local script_name
  script_name=$(basename "$0")
  cat <<HELP
$script_name (options) (<remote> <branch>)

Check build completion and prepare fabric commands.
Arguments <remote> and <branch> are optional. If provided, they let merge a custom remote branch to master instead of official dev branch.

Typical usage:
  $script_name

Example of hotfix merge:
  $script_name fmenou security/cve-1234

Options:
  -h: this help message
  -c: specific Slack Channel to speak to
  -d: branch name destination. Defaults to 'master'
  -f: force the operation without asking confirmation
  -j: launch from a build Job (implies -f force)
HELP
  exit 0
}

function is_not_human {
  git config --global --get user.name || git config --global user.name "${GITLAB_USER_EMAIL}"
  git config --global --get user.email || git config --global  user.email "${GITLAB_USER_EMAIL}"
}

function check_args {
  SLACK_CHANNEL="#eu-releases"
  to_shift=0
  force=0
  destination="master"

  while getopts "c:d:fjh" option; do
    case $option in
      c) SLACK_CHANNEL=$OPTARG; to_shift=$((to_shift+2)) ;;
      d) destination=$OPTARG; to_shift=$((to_shift+2)) ;;
      f) force=1; to_shift=$((to_shift+1)) ;;
      h) usage ;;
      j) is_not_human; force=1; to_shift=$((to_shift+1)) ;;
    esac
  done
}

function main {
  check_args "$@"
  shift $to_shift
  check_working_copy
  check_tools_up_to_date

  if [ $# = 2 ]; then
    remote_fetch=$1
    head=$1/$2
  else
    remote_fetch=$(remote_name "push")
    head=$remote_fetch/dev
  fi

  remote_push=$(remote_name "push")
  target_head="$remote_push/$destination"

  git fetch "$remote_fetch"
  git fetch "$remote_push"

  check_current_master
  check_git_username

  project=$(basename "$(git rev-parse --show-toplevel)")
  author=$(git config user.name)
  changelog=$(prepare_changelog)
  formatted_changelog=$(prepare_formatted_changelog)
  committers=$(prepare_committers)
  formatted_commiters=$(prepare_formatted_committers)
  echo -e "$changelog"
  echo -e "$committers"

  if [ "$force" == "0" ]; then
    echo -n -e "Do you want to merge and push? [y/N] "
    read answer
  else
    answer="y"
  fi
  if [ "$answer" == "y" ]; then
    merge
  fi
}

function check_working_copy {
  if [ "$(git ls-files -cdmsu | wc -l)" -ne 0 ]; then
    echo "Working copy and index not clear, can't proceed"
    git status -s
    echo "Aborting.."
    exit 1
  fi
}

function check_tools_up_to_date {
  if [ -d "$TOOLS_DIR/.git" ]; then
    pushd "$TOOLS_DIR" > /dev/null
    local tools_remote="$(remote_name "fetch")"

    git fetch $tools_remote
    if [ $(git diff $tools_remote/master | wc -l) -ne 0 ]; then
      echo -e '\033[41m /!\' "Your tools are not up-to-date." '/!\ \033[0m'
      echo "Please pull latest changes from $tools_remote"
      echo -n -e "Do you still want to continue? [y/N] "
      read answer
      if [ "$answer" != "y" ]; then
        exit 1
      fi
    fi
    popd > /dev/null
  fi
}

function check_git_username {
  if [ -z "$(git config user.name)" ]; then
    echo "Please set a git user name."
    exit 1
  fi
}

function upstream_remote {
  local direction="($1)"

  local gitlab_host="(${GITLAB_HOST}|gitlab.com)"
  local main_repos="(${GITLAB_UPSTREAM_NAMESPACE}|myteam|myanotherteam)"
  local remote

  remote=$(git remote -v | grep -E "$gitlab_host.$main_repos" | grep "$direction" | head -n1)
  if [ -z "$remote" ]; then
    >&2 echo -e '\033[41m' "No upstream remote found within /${gitlab_host}:${main_repos}/" '\033[0m'
    >&2 echo "Check/change remote url with 'git remote -v' or change the env variable GITLAB_HOST"
    exit 1
  fi

  echo "$remote"
}

function remote_group {
  local upstream
  upstream=$(upstream_remote "$@")
  upstream=${upstream#*https://}
  upstream=${upstream#*git@}
  upstream=${upstream#*:}
  upstream=${upstream%/*}
  upstream=${upstream#*/}
  echo "$upstream"
}

function remote_name {
  upstream_remote "$@" | cut -f 1
}

function check_current_master {
  if [ -f ".git/refs/heads/$destination" ]; then
    local unshared_master_commits
    unshared_master_commits=$(git rev-list "${target_head}..${destination}" | wc -l)
    if [ "$unshared_master_commits" -ne 0 ]; then
      echo "local '$destination' is ahead of $target_head by $unshared_master_commits commits:"
      git log --boundary --graph --oneline "${target_head}..${destination}"
      echo "Aborting.."
      exit 2
    fi
  fi
}

function prepare_changelog {
  echo "CHANGELOG $project - $author"
  git log --boundary --graph --oneline "${target_head}..$head"
}

function prepare_formatted_changelog {
  local scm_url
  scm_url="https://${GITLAB_HOST}/$(remote_group "push")/${project}/commit/"
  local git_format
  git_format="• <${scm_url}%h|%h> %s (%an)"
  local graph
  graph=$(git log --graph --boundary --pretty=format:"${git_format}" "${target_head}..$head")

  local simplify_graph='s/\*[ |\/\\]*//g'
  local indent='s/|[ \\\/]\{1,\}/     /g'
  local replace_boundary='s/^ *o • <\(.*\)>/◦ <\1>/g'
  local cleaned_graph="$(echo -e "$graph" | grep '[*o]' - | sed -e "$simplify_graph;$indent;$replace_boundary")"

  echo "$cleaned_graph"
}

function prepare_committers {
  echo "Includes changes from $(commiters_emails | comma_join)"
}

function prepare_formatted_committers {
    echo "Includes changes from $(email2slack "$(commiters_emails)" | comma_join)" | slack_links
}

function commiters_emails {
  local revision_range="$remote_push/$destination..$head"
  git_authors "$revision_range"
}

function git_authors {
  local revision_range="$1"
  git log --pretty="format:%ae" --no-merges "$revision_range" | sort | uniq
}

function email2slack {
  local text="$1"

  # This is a bit of hackery, but actually makes sense. Pipes creates subshells, so the content
  # of the "while read" block is executed in a different environment and the
  # outer $text is never mutated. Manually creating a subshell (with the parenthesis)
  # fixes this problem, cf https://serverfault.com/a/259342
  cat "$TOOLS_DIR/slack-usernames" | (while read line; do
    email=$(echo $line | cut -d ' ' -f1)
    slack=$(echo $line | cut -d ' ' -f2)

    text="${text//$email/$slack}"
  done

  echo -e "$text"
  )
}

function slack_links {
  xargs | sed -E "s/@([^[[:blank:],]+]*)/<@\1|\1>/g"
}

function comma_join {
  xargs | sed 's/ /, /g'
}

function merge {
  git checkout "$destination"
  git reset --hard "${target_head}"
  git merge --no-edit --commit --no-ff "$head"

  # Back to previous branch
  git checkout -

  if [ -n "$(git diff "$head..$destination")" ]; then
    echo "ERROR: git diff $head..$destination is not empty."
    echo "Ensure that dev won't override code on '$destination' (maybe a bad executed cherry-pick)."
    echo "Aborting.."
    exit 3
  else
    git push "$remote_push" "$destination"
    sha1=$(git rev-parse --short "$destination")
    formatted_subject="Merging into $destination ($author) ${sha1}$NEWLINE$formatted_commiters"
    echo -e "$formatted_changelog" | slack-speak -n "${project}" -c "${SLACK_CHANNEL}" -s "$formatted_subject"
  fi
}

main "$@"