commit cb9ec1325aa2656fb525cac4235edee51fcabcc2
Author: Knut Ahlers <knut@ahlers.me>
Date:   Sun Jan 22 00:51:06 2023 +0100

    Initial version

diff --git a/Dockerfile b/Dockerfile
new file mode 100644
index 0000000..e83849d
--- /dev/null
+++ b/Dockerfile
@@ -0,0 +1,24 @@
+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 \
+      grep \
+      openssh \
+      rsync
+
+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..f107b8b
--- /dev/null
+++ b/docker-entrypoint.sh
@@ -0,0 +1,197 @@
+#!/usr/local/bin/dumb-init bash
+set -euo pipefail
+
+: ${BASE_DIR:=.}                    # Where to create the backup dir
+: ${EXIT_ON_ERROR:=false}           # Exit on backup error (default keep running)
+: ${HETZNER_WORKAROUND:=false}      # Hetzner StorageBox needs sftp for symlinks
+: ${INTERVAL:=3600}                 # When to backup (3600 = *:00, 1800 = *:00,30)
+: ${KEEP_LAST_N:=0}                 # How many backups to keep
+: ${LATEST_LINK:=latest}            # How to name the latest link
+: ${LOCAL_DIR:=/data}               # Where to find the data to backup
+: ${NAME_SCHEMA:=%Y-%m-%d_%H-%M-%S} # How to name backup dirs, make sure to make it sortable when using KEEP_LAST_N, do not use spaces
+: ${ONESHOT:=false}                 # Run only once (backup only), set INTERVAL to 1 to execute directly on start
+: ${REMOTE_HOST:=}                  # Where to send the backups
+: ${SKIP_RESTORE_ON:=}              # File to check, if exists restore will be skipped
+: ${SSH_CONFIG_MOUNT:=~/.ssh-dist}  # Where to search for ~/.ssh contents to copy into ~/.ssh (Secret mountPath)
+
+function cleanup_old_backups() {
+  info "Starting cleanup of backups..."
+
+  for backup in $(ssh "${REMOTE_HOST}" -- ls "${BASE_DIR}" | grep -v "${LATEST_LINK}" | sort | head --lines=-${KEEP_LAST_N}); do
+    ssh "${REMOTE_HOST}" -- rm -rf "${BASE_DIR}/${backup}" || {
+      error "Failed to delete backup ${backup}"
+      return 1
+    }
+  done
+}
+
+function ensure_basedir() {
+  info "Ensuring base-dir..."
+
+  ssh "${REMOTE_HOST}" -- mkdir -p "${BASE_DIR}" || {
+    error "Failed to create base-dir."
+    return 1
+  }
+}
+
+function error() {
+  log E "$@"
+}
+
+function exit_error() {
+  if [[ $EXIT_ON_ERROR == true ]]; then
+    fatal "$@"
+    return 0
+  fi
+
+  error "$@"
+}
+
+function fatal() {
+  log F "$@"
+  exit 1
+}
+
+function import_ssh_dir() {
+  info "Importing ~/.ssh from ${SSH_CONFIG_MOUNT}"
+
+  mkdir -p ~/.ssh || {
+    error "Failed to create ~/.ssh dir."
+    return 1
+  }
+
+  rsync -a "${SSH_CONFIG_MOUNT}/" ~/.ssh/
+  chown $(id -u) ~/.ssh/*
+  chmod 0600 ~/.ssh/*
+}
+
+function info() {
+  log I "$@"
+}
+
+function link_latest() {
+  info "Creating latest link..."
+
+  local dest="$1"
+  local link="$2"
+
+  if [[ $HETZNER_WORKAROUND == true ]]; then
+    echo -e "rm ${link}\nsymlink ${dest} ${link}" | sftp "${REMOTE_HOST}" && return 0 || {
+      error "Renewing latest-link (sftp)."
+      return 1
+    }
+  fi
+
+  ssh "${REMOTE_HOST}" -- ln -sf "${dest}" "${link}" || {
+    error "Renewing latest-link (ssh)."
+    return 1
+  }
+}
+
+function log() {
+  local level=$1
+  shift
+  echo "[$(date +%H:%M:%S)][$level] $@" >&2
+}
+
+function main() {
+  [[ -n $REMOTE_HOST ]] || fatal "No REMOTE_HOST set"
+
+  if [[ -d $SSH_CONFIG_MOUNT ]]; then
+    import_ssh_dir || fatal "Failed importing SSH config."
+  fi
+
+  case "${1:-help}" in
+  backup)
+    while true; do
+      sleep $((INTERVAL - $(date +%s) % INTERVAL))
+      run_backup || exit_error "Backup failed."
+
+      if [ $KEEP_LAST_N -gt 0 ]; then
+        cleanup_old_backups
+      fi
+
+      [[ $ONESHOT != true ]] || {
+        info "ONESHOT activated, exit now"
+        break
+      }
+    done
+    ;;
+
+  restore)
+    run_restore || exit_error "Restore failed."
+    ;;
+
+  *)
+    usage
+    fatal "Action ${1:-help} called"
+    ;;
+  esac
+}
+
+function run_backup() {
+  local current="$(date +${NAME_SCHEMA})"
+  local dest="${BASE_DIR}/${current}"
+  local link="${BASE_DIR}/${LATEST_LINK}"
+
+  info "Starting backup..."
+
+  ensure_basedir || {
+    error "Failed to ensure base-dir."
+    return 1
+  }
+
+  info "Synchronizing backup..."
+  rsync -av --delete \
+    "${LOCAL_DIR}/" \
+    --link-dest "../${LATEST_LINK}/" \
+    "${REMOTE_HOST}:${dest}/" || {
+    error "Failed to sync backup-dir."
+    return 1
+  }
+
+  link_latest "${current}" "${link}" || {
+    error "Failed to create latest link."
+    return 1
+  }
+
+  info "Backup finished."
+}
+
+function run_restore() {
+  if [[ -n $SKIP_RESTORE_ON ]] && [[ -e $SKIP_RESTORE_ON ]]; then
+    info "Check-file ${SKIP_RESTORE_ON} exists, skipping restore."
+    return 0
+  fi
+
+  local link="${BASE_DIR}/${LATEST_LINK}"
+
+  info "Starting restore..."
+
+  mkdir -p "${LOCAL_DIR}" || {
+    error "Failed to ensure local dir..."
+    return 1
+  }
+
+  rsync -av --delete \
+    "${REMOTE_HOST}:${link}/" \
+    "${LOCAL_DIR}/" || {
+    error "Failed to sync remote data..."
+    return 1
+  }
+
+  info "Restore finished."
+}
+
+function usage() {
+  cat >&2 <<EOF
+Usage:
+  docker run --rm -ti \
+    -v /mydata:/data:ro \
+    -e REMOTE_HOST=user@host \
+    pvc-rsync <backup|restore>
+EOF
+
+}
+
+main "$@"