Snippets about backuping GIT repositories (in my case : forgejo usage with backups managed in an "external" way through this script, and not with "forgejo" dump command) - see here for extra details : https://codeberg.org/forgejo/forgejo/issues/2253

backup.sh

#!/bin/bash

BACKUP_DIRECTORY="/data/backups/"
LFS_DIRECTORY="/data/git/lfs/"
REPOSITORY_LOCATION="/data/git/repositories/"
MAX_BUNDLE_BACKUPS_TO_BE_KEPT=2 # have +1 compared to number of files to be kept ("2" to keep 1 file, ...)
rm -f /tmp/bundles.created.$$ /tmp/bundles.deleted.$$ /tmp/lfs.$$ >/dev/null 2>&1

find "${REPOSITORY_LOCATION}" -name "*.git" | sort | while read REPOSITORY ; do
  PARENT=$(basename $(dirname "${REPOSITORY}"))

  REPOSITORY_NEED_TO_BE_BACKUPED=0
  REPOSITORY_NAME="${REPOSITORY##*/}" # myrepo.git
  REPOSITORY_NAME="${PARENT}-${REPOSITORY_NAME%%.git*}" # owner-myrepo
  echo ""
  echo " === Working on [$REPOSITORY] => [$REPOSITORY_NAME]"
  PREVIOUS_BACKUP_FOUND=$(find "${BACKUP_DIRECTORY}" -regex ".*${REPOSITORY_NAME}-[0-9]*\.bundle" 2>/dev/null | wc -l)
  cd "${REPOSITORY}"
  LAST_COMMIT_FROM_REPOSITORY=$(git --no-pager log -1 --format="%at")
  if [[ "$PREVIOUS_BACKUP_FOUND" -eq 0 ]] ; then
    REPOSITORY_NEED_TO_BE_BACKUPED=1
    echo "   - No previous backup found, backup needed"
    # TODO this is not optimal : we will backup whole LFS folder 
    # as soon as only one repository has changes (but they may not be LFS related)
    NB_LFS_FILES=$(git lfs ls-files --all 2>/dev/null | wc -l)
    [[ "$NB_LFS_FILES" -gt 0 ]] && echo "${REPOSITORY_NAME}" >> /tmp/lfs.$$
  else
    LAST_COMMIT_FROM_BACKUP=$(find "${BACKUP_DIRECTORY}" -regex ".*${REPOSITORY_NAME}-[0-9]*\.bundle" 2>/dev/null | tail -1 | sed "s|.*-\([0-9]*\)\.bundle|\1|")
    if [[ "${LAST_COMMIT_FROM_REPOSITORY}" -gt "${LAST_COMMIT_FROM_BACKUP}" ]] ; then
      echo "   - Repo [$REPOSITORY_NAME] - last commit from repository [$LAST_COMMIT_FROM_REPOSITORY], last commit backuped [$LAST_COMMIT_FROM_BACKUP] ==> BACKUP NEEDED"
      REPOSITORY_NEED_TO_BE_BACKUPED=1
      NB_LFS_FILES=$(git lfs ls-files --all 2>/dev/null | wc -l)
      [[ "$NB_LFS_FILES" -gt 0 ]] && echo "${REPOSITORY_NAME}" >> /tmp/lfs.$$
    else
      echo "   - Repo [$REPOSITORY_NAME] - last commit from repository [$LAST_COMMIT_FROM_REPOSITORY], last commit backuped [$LAST_COMMIT_FROM_BACKUP] ==> BACKUP NOT NEEDED"
    fi
  fi
  
  if [[ "$REPOSITORY_NEED_TO_BE_BACKUPED" -eq 1 ]] ; then
    echo "   - BACKUPING REPOSITORY [$REPOSITORY_NAME]"
    git bundle create "${BACKUP_DIRECTORY}/${REPOSITORY_NAME}-${LAST_COMMIT_FROM_REPOSITORY}.bundle" --all
    echo "${REPOSITORY_NAME}-${LAST_COMMIT_FROM_REPOSITORY}.bundle" >> /tmp/bundles.created.$$

    # Delete old bundle backups to keep only "max" of them
    ls -t "${BACKUP_DIRECTORY}/${REPOSITORY_NAME}"*.bundle | tail -n +${MAX_BUNDLE_BACKUPS_TO_BE_KEPT} >> /tmp/bundles.deleted.$$
    ls -t "${BACKUP_DIRECTORY}/${REPOSITORY_NAME}"*.bundle | tail -n +${MAX_BUNDLE_BACKUPS_TO_BE_KEPT} | xargs -I {} rm {}
  fi

  cd - >/dev/null 2>&1
done

# LFS to be tarr'ed (only if needed)
if [[ -f /tmp/lfs.$$ ]] ; then
  echo "LFS backup needed for these repositories : "
  cat /tmp/lfs.$$ | sort
  tar czvf "${BACKUP_DIRECTORY}/lfs-backup.tar.gz" "${LFS_DIRECTORY}"
fi

# Summaries
if [[ -f /tmp/bundles.created.$$ ]] ; then
  echo ""
  echo "Bundles created : "
  echo "====================================="
  cat /tmp/bundles.created.$$ | sort
fi  
if [[ -f /tmp/bundles.deleted.$$ ]] ; then
  echo ""
  echo "Bundles removed : "
  echo "====================================="
  cat /tmp/bundles.deleted.$$ | sort
fi  

crontab

30			1	*	*	*	/usr/bin/docker run --rm --name forgejo-backuper -e DATE=$(date "+\%Y-\%m-\%d") --link postgresql:database_postgres -v volume_forgejo:/data/ -v volume_forgejo_backup_dumps:/data/backups/ -w /data/backups/ --entrypoint "" -e USER=git --user git codeberg.org/forgejo/forgejo:9 sh -c "forgejo dump --verbose --database postgres --skip-repository --skip-lfs-data --config /data/gitea/conf/app.ini --type tar.gz --file /data/backups/\$DATE-forgejo-dump.tar.gz" > /var/log/cron-backup-docker-forgejo.log 2>&1
5			 1	*	*	*	/usr/bin/docker run --rm --name "forgejo-backup-repositories" -v volume_forgejo:/data/ -v volume_forgejo_backup_repositories:/data/backups/ forgejo-backuper > /var/log/cron-backup-docker-forgejo-repositories.log 2>&1

Dockerfile

FROM	debian:bookworm-slim

CMD	["/backup.sh"]

RUN	apt-get update && apt-get install -y git git-lfs && \
	git lfs install && \
	groupadd -g 1000 git && \
	useradd -u 1000 -d /git/ -s /usr/bin/bash -g git -c "git" git && \
	cp -Rp /root/ /git/ && chown -R 1000:1000 /git/ && \
	apt-clean

COPY	backup.sh /backup.sh

ENV	HOME=/git/
USER	git
WORKDIR	/data/