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@eisisig
Created November 18, 2016 08:17
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convert multiple repos to monorepo
#!/bin/bash
# Merge multiple repositories into one big monorepo. Migrates every branch in
# every subrepo to the eponymous branch in the monorepo, with all files
# (including in the history) rewritten to live under a subdirectory.
#
# To use a separate temporary directory while migrating, set the GIT_TMPDIR
# envvar.
#
# To access the individual functions instead of executing main, source this
# script from bash instead of executing it.
# Name of the mono repository
MONOREPO_NAME=$1
SCRIPT_NAME=`basename "$0"`
if [[ -z "$1" ]]; then
echo "Please provide repo name: \"./$SCRIPT_NAME reponame\""
exit 0
fi
echo "Creating $MONOREPO_NAME"
${DEBUGSH:+set -x}
if [[ "$BASH_SOURCE" == "$0" ]]; then
is_script=true
set -eu -o pipefail
else
is_script=false
fi
function read_repositories {
sed -e 's/#.*//' | grep .
}
function remote-branches {
git branch -r | grep "^ $1/" | sed -e 's_.*/__'
}
# Create a monorepository in a directory "core". Read repositories from STDIN:
# one line per repository, with two space separated values:
#
# 1. The (git cloneable) location of the repository
# 2. The name of the target directory in the core repository
function create-mono {
# Pretty risky, check double-check!
if [[ "${1:-}" == "--continue" ]]; then
if [[ ! -d "$MONOREPO_NAME" ]]; then
echo "--continue specified, but nothing to resume" >&2
exit 1
fi
pushd "$MONOREPO_NAME"
else
if [[ -d "$MONOREPO_NAME" ]]; then
echo "Target repository directory $MONOREPO_NAME already exists." >&2
return 1
fi
mkdir "$MONOREPO_NAME"
pushd "$MONOREPO_NAME"
git init
fi
read_repositories | while read repo name; do
if [[ -z "$name" ]]; then
echo "pass REPOSITORY NAME pairs on stdin" >&2
return 1
fi
echo "Merging in $repo.." >&2
git remote add "$name" "$repo"
git fetch -qa "$name"
# Merge every branch from the sub repo into the mono repo, into a
# branch of the same name (create one if it doesn't exist).
remote-branches "$name" | while read branch; do
if git rev-parse -q --verify "$branch"; then
# Branch already exists, just check it out (and clean up the working dir)
git checkout -q "$branch"
git checkout -q -- .
git clean -f -d
else
# Create a fresh branch with an empty root commit"
git checkout -q --orphan "$branch"
# The ignore unmatch is necessary when this was a fresh repo
git rm -rfq --ignore-unmatch .
git commit -q --allow-empty -m "Root commit for $branch branch"
fi
git merge -q --no-commit --allow-unrelated-histories -s ours "$name/$branch"
git read-tree --prefix="$name/" "$name/$branch"
git commit -q --no-verify --allow-empty -m "Merging $name to $branch"
done
done
git checkout -q master
git checkout -q .
}
if [[ "$is_script" == "true" ]]; then
create-mono "${1:-}"
fi
@arronmabrey
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