use atomic mv to create backup

jenkinsci · Apr 12, 2024 · ba9ea5a · ba9ea5a
1 parent cf49a4a
commit ba9ea5a
Showing 1 changed file with 6 additions and 3 deletions.
diff --git a/backup/pvc/bin/backup.sh b/backup/pvc/bin/backup.sh
@@ -5,7 +5,9 @@ set -eo pipefail
 [[ ! $# -eq 1 ]] && echo "Usage: $0 backup_number" && exit 1;
 [[ -z "${BACKUP_DIR}" ]] && echo "Required 'BACKUP_DIR' env not set" && exit 1;
 [[ -z "${JENKINS_HOME}" ]] && echo "Required 'JENKINS_HOME' env not set" && exit 1;
-BACKUP_TMP_DIR=$(mktemp -d)
+
+# create temp dir on the same filesystem with a BACKUP_DIR to be able use atomic mv enstead of copy
+BACKUP_TMP_DIR=$(mktemp -d --tmpdir=${BACKUP_DIR})
 trap "test -d "${BACKUP_TMP_DIR}" && rm -fr "${BACKUP_TMP_DIR}"" EXIT SIGINT SIGTERM
 
 backup_number=$1
@@ -23,12 +25,13 @@ tar --zstd -C "${JENKINS_HOME}" -cf "${BACKUP_TMP_DIR}/${backup_number}.tar.zstd
 
 if [[ "$ret" -eq 0 ]]; then
   echo "Backup was completed without warnings"
-  mv "${BACKUP_TMP_DIR}/${backup_number}.tar.zstd" "${BACKUP_DIR}/${backup_number}.tar.zstd"
 elif [[ "$ret" -eq 1 ]]; then
   echo "Backup was completed with some warnings"
-  mv "${BACKUP_TMP_DIR}/${backup_number}.tar.zstd" "${BACKUP_DIR}/${backup_number}.tar.zstd"
 fi
 
+# atomically create a backup file
+mv "${BACKUP_TMP_DIR}/${backup_number}.tar.zstd" "${BACKUP_DIR}/${backup_number}.tar.zstd"
+
 rm -rf "${BACKUP_TMP_DIR}"
 [[ ! -s ${BACKUP_DIR}/${backup_number}.tar.zstd ]] && echo "backup file '${BACKUP_DIR}/${backup_number}.tar.zstd' is empty" && exit 1;