When you create a lvm snapshot backup with freezer-agent, function get_lvm_info() of snapshot/lvm.py may produce a null string mount_point which will cause "Critical Error: list index out of range" in function lvm_guess().
- reproduce
# freezer-agent --debug --snapshot mysql_lv --lvm-srcvol /dev/cl/var --lvm-volgroup cl --path-to-backup /var/lib/mysql --mysql-conf /root/.freezer/freezer-mysql.conf --storage swift --container freezer_mysql-backup-prod --mode mysql --exclude "\*.lock" --backup-name mysql-test
Critical Error: list index out of range
- feezer-agent logs:
2020-04-23 12:35:58.646 7831 ERROR freezer.main [-] list index out of range: IndexError: list index out of range
2020-04-23 12:35:58.646 7831 ERROR freezer.main Traceback (most recent call last):
2020-04-23 12:35:58.646 7831 ERROR freezer.main File "/usr/lib/python2.7/site-packages/freezer/main.py", line 279, in main
2020-04-23 12:35:58.646 7831 ERROR freezer.main freezer_main(backup_args)
2020-04-23 12:35:58.646 7831 ERROR freezer.main File "/usr/lib/python2.7/site-packages/freezer/main.py", line 144, in freezer_main
2020-04-23 12:35:58.646 7831 ERROR freezer.main return run_job(backup_args, storage)
2020-04-23 12:35:58.646 7831 ERROR freezer.main File "/usr/lib/python2.7/site-packages/freezer/main.py", line 157, in run_job
2020-04-23 12:35:58.646 7831 ERROR freezer.main response = freezer_job.execute()
2020-04-23 12:35:58.646 7831 ERROR freezer.main File "/usr/lib/python2.7/site-packages/freezer/job.py", line 205, in execute
2020-04-23 12:35:58.646 7831 ERROR freezer.main backup_level = self.backup(app_mode)
2020-04-23 12:35:58.646 7831 ERROR freezer.main File "/usr/lib/python2.7/site-packages/freezer/job.py", line 258, in backup
2020-04-23 12:35:58.646 7831 ERROR freezer.main snapshot_taken = snapshot.snapshot_create(self.conf)
2020-04-23 12:35:58.646 7831 ERROR freezer.main File "/usr/lib/python2.7/site-packages/freezer/snapshot/snapshot.py", line 47, in snapshot_create
2020-04-23 12:35:58.646 7831 ERROR freezer.main return lvm.lvm_snap(backup_opt_dict)
2020-04-23 12:35:58.646 7831 ERROR freezer.main File "/usr/lib/python2.7/site-packages/freezer/snapshot/lvm.py", line 200, in lvm_snap
2020-04-23 12:35:58.646 7831 ERROR freezer.main lvm_info = get_lvm_info(backup_opt_dict.path_to_backup)
2020-04-23 12:35:58.646 7831 ERROR freezer.main File "/usr/lib/python2.7/site-packages/freezer/snapshot/lvm.py", line 240, in get_lvm_info
2020-04-23 12:35:58.646 7831 ERROR freezer.main mount_point_path, mount_points, 'mount')
2020-04-23 12:35:58.646 7831 ERROR freezer.main File "/usr/lib/python2.7/site-packages/freezer/snapshot/lvm.py", line 281, in lvm_guess
2020-04-23 12:35:58.646 7831 ERROR freezer.main mount_path = mount_list[2]
2020-04-23 12:35:58.646 7831 ERROR freezer.main IndexError: list index out of range
2020-04-23 12:35:58.646 7831 ERROR freezer.main
2020-04-23 12:35:58.647 7831 CRITICAL freezer.main [-] Run freezer agent process unsuccessfully: IndexError: list index out of range
2020-04-23 12:35:58.647 7831 CRITICAL freezer.main [-] Critical Error: list index out of range
- analysis
When the mountpoint of freezer-agent option path-to-backup is invisible in /proc/mounts, function get_lvm_info() will try to use subprocess.Popen([mount]) to retieve mount-points.
However, simply use mount_points = mount_out.split('\n') may create a null string in the last of list mount_points. The null string eventually causes a list index out of range error.
e.g.
2020-04-23 12:35:58.645 7831 INFO freezer.snapshot.lvm [-] mount_points: ['sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime)', 'proc on /proc type proc (rw,nosuid,nodev,noexec,relatime)', 'devtmpfs on /dev type devtmpfs (rw,nosuid,size=3994280k,nr_inodes=998570,mode=755)', 'securityfs on /sys/kernel/security type securityfs (rw,nosuid,nodev,noexec,relatime)', 'tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev,size=4005196k,nr_inodes=1001299)', 'devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000)', 'tmpfs on /run type tmpfs (rw,nosuid,nodev,size=4005196k,nr_inodes=1001299,mode=755)', 'tmpfs on /sys/fs/cgroup type tmpfs (ro,nosuid,nodev,noexec,size=4005196k,nr_inodes=1001299,mode=755)', 'cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,xattr,release_agent=/usr/lib/systemd/systemd-cgroups-agent,name=systemd)', 'pstore on /sys/fs/pstore type pstore (rw,nosuid,nodev,noexec,relatime)', 'cgroup on /sys/fs/cgroup/perf_event type cgroup (rw,nosuid,nodev,noexec,relatime,perf_event)', 'cgroup on /sys/fs/cgroup/devices type cgroup (rw,nosuid,nodev,noexec,relatime,devices)', 'cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,cpuacct,cpu)', 'cgroup on /sys/fs/cgroup/memory type cgroup (rw,nosuid,nodev,noexec,relatime,memory)', 'cgroup on /sys/fs/cgroup/pids type cgroup (rw,nosuid,nodev,noexec,relatime,pids)', 'cgroup on /sys/fs/cgroup/blkio type cgroup (rw,nosuid,nodev,noexec,relatime,blkio)', 'cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,nosuid,nodev,noexec,relatime,cpuset)', 'cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,freezer)', 'cgroup on /sys/fs/cgroup/net_cls,net_prio type cgroup (rw,nosuid,nodev,noexec,relatime,net_prio,net_cls)', 'cgroup on /sys/fs/cgroup/hugetlb type cgroup (rw,nosuid,nodev,noexec,relatime,hugetlb)', 'configfs on /sys/kernel/config type configfs (rw,relatime)', '/dev/mapper/cl-root on / type xfs (rw,relatime,attr2,inode64,noquota)', 'systemd-1 on /proc/sys/fs/binfmt_misc type autofs (rw,relatime,fd=35,pgrp=1,timeout=300,minproto=5,maxproto=5,direct)', 'hugetlbfs on /dev/hugepages type hugetlbfs (rw,relatime)', 'mqueue on /dev/mqueue type mqueue (rw,relatime)', 'debugfs on /sys/kernel/debug type debugfs (rw,relatime)', '/dev/mapper/cl-home on /home type xfs (rw,relatime,attr2,inode64,noquota)', '/dev/mapper/cl-var on /var type xfs (rw,relatime,attr2,inode64,noquota)', '/dev/vda1 on /boot type xfs (rw,relatime,attr2,inode64,noquota)', 'sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw,relatime)', 'tmpfs on /run/user/0 type tmpfs (rw,nosuid,nodev,relatime,size=381612k,mode=700)', '/dev/mapper/cl-freezer_backup_snap_8d4235d457be404bb869ad7a7774625d on /var/lib/freezer/mount_8d4235d457be404bb869ad7a7774625d type xfs (ro,relatime,nouuid,norecovery,attr2,inode64,noquota)', '']
Fix proposed to branch: master
Review: https:/