Merging m3db/* repos into m3db/m3

monorepo-merge.sh

#!/bin/bash

set -euo pipefail

usage() { 
    echo "usage: $0 <repo> <name>"
    echo
    echo "<repo>"
    echo "    The repo link, e.g. https://github.com/m3db/m3coordinator.git"
    echo
    echo "<name>"
    echo "    The name of the directory within 'src/', conventionally the repo name with the 'm3' prefix stripped, e.g. coordinator"
} 

if [[ $# -ne 2 ]]; then
    usage
    exit 1
fi

# git clone repo, e.g. https://github.com/m3db/m3coordinator.git
repo="$1"
# Name of the directory within src/, conventionally the repo name with the
# m3 prefix stripped, e.g. coordinator
name="$2"
oldname="$(echo "$repo" | sed 's#^.*/\([a-zA-Z0-9]*\).*#\1#')"
folder="src/$name"
monobranch="monorepo-merge-$name"

mkdir -p "$folder"
git remote add "$name" "$repo"
echo "Fetching '$name/master'..."
# Complains about no common commits, which is expected
git fetch -q "$name" master 2> /dev/null

# Hack to rewrite history to prepend $folder/ to all files
echo "Rewriting history to change directory structure..."
# NOTE for debugging: there is a tab character in the sed. Not all versions
# of sed interpret \t as a tab character.
git filter-branch -f --index-filter \
    'git ls-files -s | sed "s%	\"*%&'"$folder"'/%" |
     GIT_INDEX_FILE=$GIT_INDEX_FILE.new git update-index --index-info &&
     mv "$GIT_INDEX_FILE.new" "$GIT_INDEX_FILE"' "$name/master"

echo "Checking out branch '$monobranch'"
# Complains about non-empty .ci/ directory (submodule), but it's okay because
# we don't do modifications to it.
git checkout -q --no-track -b "$monobranch" "$name/master" 2> /dev/null

echo "Rebasing on 'master'..."
# Complains about non-empty .ci/ directory (submodule), but it's okay because
# we don't do modifications to it.
git rebase -q --committer-date-is-author-date master 2> /dev/null
# Clean up remote
git remote remove "$name"

echo "Cleaning up submodules..."
rm -rf "$folder/.ci" "$folder/.gitmodules" ".git/modules/$folder/.ci"
git rm -q --cached "$folder/.ci"

echo "Replacing 'github.com/m3db/$oldname' with 'github.com/m3db/m3/src/$name'.."
find . -name "*.go" -exec sed -i '' -e "s#github.com/m3db/$oldname#github.com/m3db/m3/src/$name#g" '{}' \;

echo "Done!"