CRIU is a tool for checkpointing and restoring Linux containers and processes. It aims to fully support Linux containers and integrate with projects like OpenVZ, OpenMPI, Systemd, Docker, and LXC. CRIU uses plugins and RPC/library interfaces to support checkpointing processes across ARM64, i386, and other architectures. Recent improvements include images deduplication, improved performance and stability, and added support for more Linux objects in checkpoints. CRIU is mostly written in C by a team of 31 contributors and has over 7,900 commits and 105,882 lines of code maintained on GitHub.

1. Andrey Vagin <avagin@openvz.org><
CRIU - Checkpoint/Restore in User-space

2. 2
Goals
● Full support of Linux Containers
● Integration with other projects
– OpenVZ
– OpenMPI
– Systemd
– Docker
– LXC
● Support of ARM64 and i386
● RKU (seamless kernel update)

3. 3
Where is CRIU now?

4. 4
Who is CRIU user?

5. 5
What is new?
● All patches are in the upstream kernel
● Images deduplication in incremental dumps
● RPC, library
● Improve stability and reliability
● Improve performance
● Plugins
● In a queue
– Nested mount name-spaces (near future)
– User name-space
● Support new objects: tun; posix-timers; shared, slave mounts; btrfs and
nfs; inotify

6. 6
Plugins
● Unknown file types
● External dependencies
– Unix sockets (dbus, journald, rsyslog, etc)
– Unknown character and block devices.
– External bind-mounts
– External net devices
– External something else

7. 7
RPC and libcriu.so
● Easy to use from other languages
– The protocol is based on protobuf messages
● Allow to use CRIU for unprivileged processes
– CRIU still requires root privileges to run
– UNIX domain sockets support passing credentials
● Self-dump
– A process can request to dump itself

8. 8
In a Nutshell, CRIU...
.... has had 7,904 commits made by 31 contributors
representing 105,882 lines of code
... is mostly written in C
with a very low number of source code comments
... has a young, but established codebase
maintained by a large development team
with decreasing Y-O-Y commits
https://www.ohloh.net/p/criu#

9. 9
P.haul (process hauler) - Live migration using CRIU
Live migration using CRIU
● Iterative
● Optimal
● Customizable
#./p.haul ovz 100 10.30.25.213
Migration succeeded
total time is ~2.86 sec
frozen time is ~1.99 sec
( ['0.27', '0.18', '1.55'] )
restore time is ~0.86 sec
img sync time is ~0.32 sec

10. 10
Compel
- a foreign process to execute code blob provided
● extensible via plugins mechanism
● supplied with precompiled plugins
– system calls
– printf's
– unix SCM messages
● still in alfa stage

11. Thank you
http://criu.org