git-backport

git-backport

#!/bin/bash
set -e
# set -x

TOKEN=$(git config --get github.token)
if [ -z "$TOKEN" ]; then
  echo 'Please create a personal github token and add it to your git config with git config --global github.token <token>'
  echo 'https://github.com/settings/tokens'
  exit 1
fi

if [ -z "$1" -o -z "$2" ]; then
  echo 'Usage: git backport <pr> <release> [remote]'
  exit 1
fi

PR="$1"
RELEASE="$2"
REMOTE="${3:-origin}"

NEWBRANCH="$RELEASE-backport-$PR"

CURR=$(git status | grep 'On branch' | sed -e 's/On branch //')

REPO=$(git remote -v | grep "^$REMOTE" | head -n1 | sed -r -e 's/.*[:\/](.*\/.*?)(.git?) .*/\1/')
if [ -z "$REPO" ]; then
  echo "Couldn't get repo"
  exit 1
fi

PULL=$(curl -sS -H "Authorization: token $TOKEN" "https://api.github.com/repos/$REPO/pulls/$PR")

PATCH_URL=$(echo "$PULL" | jq -r .patch_url)
if [ "$PATCH_URL" = "null" ]; then
  echo "Couldn't get PR info: $PULL"
  exit 2
fi

BODY=$(echo "$PULL" | jq .body)
BODY='"'"Backport #$PR to $RELEASE\r\n\r\n${BODY:1}"

if [ "$CURR" = "$NEWBRANCH" ]; then
  echo "Continuing..."
  CURR="master"
else
  echo "Creating branch $NEWBRANCH to backport #$PR into $RELEASE"
  git checkout -q -B "$NEWBRANCH" "$RELEASE"

  PATCH=$(curl -sSL -H "Authorization: token $TOKEN" "$PATCH_URL")

  trap "echo 'Patch could not be applied, fix issues then run git backport $PR $RELEASE'" ERR
  echo "$PATCH" | git am -3
  trap ERR
fi

git push "$REMOTE" "$NEWBRANCH":"$NEWBRANCH"

NEWPULL=$(curl -sS -H "Authorization: token $TOKEN" "https://api.github.com/repos/$REPO/pulls" -d '{"title":"Backport #'"$PR to $RELEASE"'","head":"'"$NEWBRANCH"'","base":"'"$RELEASE"'","body":'"$BODY"',"maintainer_can_modify":true}')

NEWPR=$(echo "$NEWPULL" | jq -r .number)
if [ "$NEWPR" = "null" ]; then
  echo "Couldn't create PR: $NEWPULL"
  exit 3
fi

echo "Opened backport PR #$NEWPR: https://github.com/$REPO/pull/$NEWPR"

git checkout -q "$CURR"