commit 5d927bc5731e798256a4c627ad4b1ccb6578e8ca
Author: Knut Ahlers <knut@ahlers.me>
Date:   Fri Mar 10 17:50:48 2023 +0100

    Initial version

diff --git a/Dockerfile b/Dockerfile
new file mode 100644
index 0000000..1401058
--- /dev/null
+++ b/Dockerfile
@@ -0,0 +1,26 @@
+FROM bash:5 as prefetch
+
+ARG DUMB_INIT_VERSION=1.2.5
+
+RUN set -ex \
+ && apk --no-cache add \
+      curl \
+ && curl -sSfLo /dumb-init "https://github.com/Yelp/dumb-init/releases/download/v${DUMB_INIT_VERSION}/dumb-init_${DUMB_INIT_VERSION}_x86_64" \
+ && chmod 0755 /dumb-init
+
+
+FROM bash:5
+
+RUN set -ex \
+ && apk --no-cache add \
+      coreutils \
+      curl \
+      git \
+      grep \
+      openssh
+
+COPY --from=prefetch  /dumb-init            /usr/local/bin/
+COPY                  docker-entrypoint.sh  /usr/local/bin/
+
+ENTRYPOINT ["/usr/local/bin/docker-entrypoint.sh"]
+
diff --git a/docker-entrypoint.sh b/docker-entrypoint.sh
new file mode 100755
index 0000000..f240578
--- /dev/null
+++ b/docker-entrypoint.sh
@@ -0,0 +1,124 @@
+#!/usr/local/bin/dumb-init bash
+set -euo pipefail
+
+: ${BRANCH:=master}          # Branch to work with when syncing
+: ${CHOWN_UID:=}             # ID of the user to chown the repo files to
+: ${CHOWN_GID:=${CHOWN_UID}} # ID of the group to chown the repo files to
+: ${INTERVAL:=300}           # How often to sync with remote
+: ${LOCAL_DIR:=/data}        # Where to find the data to backup
+: ${PING_DOWN:=}             # Send a ping (HTTP GET) to this URL when an exit-error ocurred
+: ${PING_MAX_TIME:=5}        # Time in seconds to timeout the ping request
+: ${PING_UP:=}               # Send a ping (HTTP GET) to this URL when backup finished successfully
+: ${REMOTE:=}                # Remote to sync the branch to
+
+function error() {
+  if [[ -n $PING_DOWN ]]; then
+    curl -sS -m ${PING_MAX_TIME} -o /dev/null "${PING_DOWN}"
+  fi
+
+  log E "$@"
+}
+
+function fatal() {
+  log F "$@"
+  exit 1
+}
+
+function info() {
+  log I "$@"
+}
+
+function log() {
+  local level=$1
+  shift
+  echo "[$(date +%H:%M:%S)][$level] $@" >&2
+}
+
+function main() {
+  pushd "${LOCAL_DIR}"
+
+  info "Marking local dir save..."
+  git config --global --add safe.directory "$(pwd)"
+
+  case "${1:-help}" in
+  sync)
+    run_sync || fatal "Backup failed."
+    ;;
+
+  restore)
+    run_restore || failed "Restore failed."
+    ;;
+
+  *)
+    usage
+    fatal "Action ${1:-help} called"
+    ;;
+  esac
+}
+
+function run_restore() {
+  if [[ -d .git ]]; then
+    info "Found .git directory, skipping restore."
+    return 0
+  fi
+
+  info "Initializing empty git repository..."
+  git init -b ${BRANCH}
+
+  info "Setting up remote..."
+  git remote add origin "${REMOTE}"
+  git branch -u origin "${BRANCH}"
+
+  info "Fetching remote to reset..."
+  git fetch ${REMOTE} ${BRANCH} || {
+    error "Fetch failed (exit $?)"
+    continue
+  }
+
+  info "Resetting to remote state..."
+  git reset --hard FETCH_HEAD
+}
+
+function run_sync() {
+  while true; do
+    next_run=$((INTERVAL - $(date +%s) % INTERVAL))
+    info "Sleeping ${next_run}s to next sync..."
+    sleep ${next_run}
+
+    info "Fetching remote to rebase..."
+    git fetch ${REMOTE} ${BRANCH} || {
+      error "Fetch failed (exit $?)"
+      continue
+    }
+
+    info "Rebasing upon remote..."
+    git rebase FETCH_HEAD || {
+      error "Rebase failed (exit $?)"
+      continue
+    }
+    [[ -z $CHOWN_UID ]] || chown -R ${CHOWN_UID}:${CHOWN_GID} .
+
+    info "Pushing to remote..."
+    git push ${REMOTE} ${BRANCH} || {
+      error "Push failed (exit $?)"
+      continue
+    }
+
+    if [[ -n $PING_UP ]]; then
+      curl -sS -m ${PING_MAX_TIME} -o /dev/null "${PING_UP}"
+    fi
+  done
+}
+
+function usage() {
+  cat >&2 <<EOF
+Usage:
+  docker run --rm -ti \
+    -v /mydata:/data:ro \
+    -w /data \
+    -e REMOTE_HOST=user@host \
+    pvc-git <sync|restore>
+EOF
+}
+
+main "$@"