git-push-fork-to-upstream-branch

#!/bin/bash

set -eo pipefail

: ${GPF_UPSTREAM_BRANCH:=trigger-integration}
: ${GPF_USE_SSH:=""}

UPSTREAM_REPO=$1
BRANCH_SPEC=$2
NUM_COLONS=$(echo "$BRANCH_SPEC" | awk -F: '{print NF-1}')

if [ "$#" -ne 2 ] || [ "$NUM_COLONS" -ne 1 ] ; then
    echo "Usage: $0 <upstream_repository> <fork_username>:<fork_branchname>"
    exit 1
fi

SOURCE_GH_USER=$(echo "$BRANCH_SPEC" | awk -F: '{print $1}')
SOURCE_BRANCH=$(echo "$BRANCH_SPEC" | awk -F: '{print $2}')
REPO_NAME=$(git remote get-url --push origin | awk -F/ '{print $NF}' | sed 's/\.git$//')

git remote remove fork-to-test || echo "Added new remote fork-to-test"
if [ -n "$GPF_USE_SSH" ]; then
    git remote add fork-to-test git@github.com:$SOURCE_GH_USER/$REPO_NAME.git
else
    git remote add fork-to-test https://github.com/$SOURCE_GH_USER/$REPO_NAME.git
fi
git fetch --all
git push --force $UPSTREAM_REPO "refs/remotes/fork-to-test/$SOURCE_BRANCH:refs/heads/$GPF_UPSTREAM_BRANCH"
git remote remove fork-to-test || echo "Removed new remote fork-to-test"

cat <<EOF
Forked branch '$BRANCH_SPEC' has been pushed to $UPSTREAM_REPO branch '$GPF_UPSTREAM_BRANCH'
EOF