use ssh key file

code/backup_rsync_git.sh

@@ -37,6 +37,18 @@ for var in "${required_vars[@]}"; do
   fi
 done
 
+if [[ -z "${RSYNC_RSH:-}" && -z "${SSH_KEY_FILE:-}" ]]; then
+  echo "Missing SSH config: set SSH_KEY_FILE or RSYNC_RSH" >&2
+  exit 1
+fi
+
+if [[ -n "${SSH_KEY_FILE:-}" && ! -r "$SSH_KEY_FILE" ]]; then
+  echo "SSH key file not readable: $SSH_KEY_FILE" >&2
+  exit 1
+fi
+
+mkdir -p "$RSYNC_TARGET_DIR"
+
 repo_abs="$(cd "$RSYNC_TARGET_DIR" && pwd)"
 
 rel_target="."
@@ -50,7 +62,14 @@ git_target() {
 }
 
 if [[ -n "${RSYNC_RSH:-}" ]]; then
-  rsync -az --delete -e "$RSYNC_RSH" "$RSYNC_SOURCE" "$repo_abs/"
+  rsync_rsh="$RSYNC_RSH"
+else
+  ssh_options="${SSH_OPTIONS:--o IdentitiesOnly=yes -o StrictHostKeyChecking=yes}"
+  rsync_rsh="ssh -i $SSH_KEY_FILE $ssh_options"
+fi
+
+if [[ -n "${rsync_rsh:-}" ]]; then
+  rsync -az --delete -e "$rsync_rsh" "$RSYNC_SOURCE" "$repo_abs/"
 else
   rsync -az --delete "$RSYNC_SOURCE" "$repo_abs/"
 fi