druid-backport.sh

#!/bin/bash -eux

# Note: assumes "base" and "milestone" are the same (for the backport PR)

base="$1"
pr="$2"
myrepo="gianm"
backport="backport-$pr-to-$base"

if [ "$(curl -u "$myrepo:$GIT_TOKEN" -s https://api.github.com/repos/druid-io/druid/pulls/"$pr" |jq -r '.merged')" != "true" ]
then
  echo "PR $2 not yet merged" >&2
  exit 1
fi

milestone="$(curl -u "$myrepo:$GIT_TOKEN"  -s https://api.github.com/repos/druid-io/druid/milestones | jq '.[]|select(.title == "$base")|.number')"
title="$(curl -u "$myrepo:$GIT_TOKEN" -s https://api.github.com/repos/druid-io/druid/pulls/"$pr" |jq '.title'|perl -pe's/^"/"[Backport] /')"
commit="$(git log --pretty=oneline master |perl -nle '/^(\w+)\s.+\(#'"$pr"'\)$/ && print $1' | perl -pe'$x++; END { die unless $x == 1 }')"

git checkout "$base"
git pull

if git rev-list "$base" | fgrep -q "$commit"
then
  exit 0
fi

git branch -D "$backport" ||: >/dev/null 2>&1
git checkout -b "$backport"
git cherry-pick "$commit"
git push --set-upstream "$myrepo" "$backport"

if [ -n "$GIT_TOKEN" ]
then
  curl -u "$myrepo:$GIT_TOKEN" -XPOST -d@- https://api.github.com/repos/druid-io/druid/pulls <<EOF
{
  "title"     : $title,
  "head"      : "$myrepo:$backport",
  "base"      : "$base",
  "body"      : "Backport of #$pr to $base.",
  "milestone" : "$milestone",
  "labels"    : ["Backport"]
}
EOF

else
  echo "GitHub personal token not provided, not submitting pull request" >&2
  exit 1
fi