git-mirror

#!/bin/bash
# Manage a collection of github mirrors.
#
# This script provides functionality to clone and update git
# repositories as mirrors. The update functionality is silent on
# successful updates and is designed to be called in an automated way,
# such as with cron.
#
# All mirror repositories are assumed to be contained under one base
# directory (by default ~/public_git), configurable via a flag.
set -o errexit

print_usage() {
    echo "git mirror [--base=<base_dir>] [update [repo...]]"
    echo "git mirror [--base=<base_dir>] clone <url>"
}

opts=$(getopt -o hb: --long help,base: -n 'git-mirror' -- "$@")
eval set -- "$opts"

base_dir="$HOME/public_git"
action="update"
urls=()
repo_dirs=()

while true; do
    case "$1" in
	-h|--help) print_usage; exit 0 ;;
	-b|--base)
	    shift
	    base_dir="$1"
	    shift
	    ;;
	--) shift; break ;;
	*) echo "Option parse error"; exit 1; ;;
    esac
done

while true; do
    case "$1" in
	update|"")
	    action="update"
	    if [[ "$#" -gt 1 ]]; then
		shift
		for repo_name in "$@"; do
		    repo_dirs+=("$base_dir/$repo_name")
		done
	    else
		while IFS= read -r -d '' repo_dir; do
		    repo_dirs+=("$repo_dir")
		done < <(find "$base_dir" -maxdepth 1 -type d -name '*.git' -print0)
	    fi
	    break
	    ;;
	clone)
	    action="clone"
	    [ "$#" -gt 1 ] || (print_usage ; exit 1)
	    shift
	    urls=("$@")
	    break
	    ;;
	*)
	    print_usage
	    exit 1
    esac
done
	       
update_mirror() {
    local repo_dir="$1"
    local repo_url
    repo_url=$(git --git-dir="$repo_dir" config --get remote.origin.url)

    # Fetch from remote and update upstream refs
    git --git-dir="$repo_dir" remote update --prune > /dev/null

    # Get additional information for certain upstream repos
    local host
    host=$(echo "$repo_url" \
	       | sed -n --regexp-extended 's|https?://([^/]*).*|\1|p')
    case "$host" in
	github.com)
	    local slug
	    slug=$(echo "$repo_url" \
		       | perl -pe 's|^https?://github.com/(.*?)(\.git)?$|\1|p')
	    local username
	    username=$(echo "$slug" | sed -nr 's|([^/]*)/.*|\1|p')
	    local repo
	    repo=$(echo "$slug" | sed -nr 's|[^/]*/(.*)|\1|p')

	    curl --silent --show-error \
		 "https://api.github.com/repos/$username/$repo" \
		| jq .description --raw-output > "$repo_dir/description"
	    ;;
	*)
	    ;;
    esac
}

case "$action" in
    update)
	for repo_dir in "${repo_dirs[@]}"; do
	    update_mirror "$repo_dir" || echo "Error updating $repo_dir" >&2
	done
	;;
    clone)
	for repo_url in "${urls[@]}"; do
	    git -C "$base_dir" clone --mirror "$repo_url"
	done
	;;
esac