Debugging

Raise verbosity

Make sure you use the -v4 option for extended logging and find logs in the work/images directories.

Getting core files

If CRIU crashes it's useful to build it with debug info and look into core file.

• build CRIU with debug info make DEBUG=1
• setup core file generation which depends on distro settings, usually the core generation template is sitting in /proc/sys/kernel/core_pattern, see more details at core.5

Then upload core file into debugger gdb criu core-file and type bt command to fetch a backtrace.

Docker C/R

Docker keeps images in and logs in /var/lib/docker/containers//checkpoints/chp_/criu.work/

Tracing

CRIU uses ptrace(), so strace can't be used in some cases. perf trace is an alternative way. It isn't so informative, but it is still better than nothing.

Images

The CRIT tool can help to decode images into a human readable format.