Welcome to CRIU, a project to implement checkpoint/restore functionality for Linux.
Checkpoint/Restore In Userspace, or CRIU (pronounced kree-oo, IPA: /krɪʊ/, Russian: криу), is a Linux software. It can freeze a running container (or an individual application) and checkpoint its state to disk. The data saved can be used to restore the application and run it exactly as it was during the time of the freeze. Using this functionality, application or container live migration, snapshots, remote debugging, and many other things are now possible.
CRIU started as a project of Virtuozzo, and grew with the tremendous help from the community. It is currently used by (integrated into) OpenVZ, LXC/LXD, Docker, Podman, and other software, and packaged for many Linux distributions.
- Usage scenarios
- Ideas how criu can be used (some are crazy indeed)
- Collection of real world examples of how to use CRIU. Some are complex, some are not. HOW TO dump a simple loop might be the best one to start with. Also a set of asciinema records for real-life examples.
- What can change after C/R
- CRIU cannot (yet) save and restore every single bit of tasks' state. This page describes what bits visible through standard kernel API are such.
- What cannot be checkpointed
- What an application could do to make CRIU refuse to dump it.
- Ways to communicate with CRIU community
If you're interested in CRIU development, please subscribe to the criu mailing list: https://lists.openvz.org/mailman/listinfo/criu
- Description of image files format
- CRIU can call plugins provided by people
- Upstream kernel commits
- Mainline kernel commits tracker
- Recent commits
- CRIU tool repository commits
- Kernel's manpages commits tracker
- ZDTM Test Suite
- Zero downtime test suite
- Current TODO list
- User namespace
- Implementing user namespace support
- What to keep in mind when writing new code
- Code coverage results
- Shows how zdtm run covers the criu code paths
Under the hood
- 2023-04-20, A Dynamic Checkpoint Interval Decision Algorithm for Live Migration-Based Drone-Recovery System
- 2023-03-10, Forensic Container Analysis
- 2023-01-14, Async-fork: Mitigating Query Latency Spikes Incurred by the Fork-based Snapshot Mechanism from the OS Level
- 2022-12-05, Forensic container checkpointing in Kubernetes
- 2022-11-13, Out of hypervisor (OoH): efficient dirty page tracking in userspace using hardware virtualization feature
- 2022-08-07, iContainer: Consecutive Checkpointing with Rapid Resilience for Immortal Container-based Services
- 2022-08-03, Demonstration of Containerized Central Unit Live Migration in 5G Radio Access Network