Action scripts

With the --action-script command line option, CRIU can call your action scripts (also known as hooks) at various stages of dumping/restoring. The following hooks are available:

pre-dump

called before the beginning of dump

post-dump

called when CRIU finished dumping tasks and before unfreezing them

pre-restore

called before the beginning of restore

post-restore

called when CRIU has finished restoring tasks and before unlocking the network

network-lock

request to lock a container network (used by Docker and LXC)

network-unlock

requested to unlock a container network (used by Docker and LXC)

setup-namespaces

called when the root task is alive and new set of namespaces is created to set them up

post-setup-namespaces

called after namespaces are configured

pre-resume

called at the moment when processes and resources are already restored but not yet in running state

post-resume

called at the very end, when everything is restored and processes were resumed

orphan-pts-master

called after master pty is opened and unlocked (used by Docker). Used only in RPC mode, and the notification message contains a file descriptor for the master pty.

CLI

These hooks are added with the --action-script shell-code-to-execute option. When called, the CRTOOLS_SCRIPT_ACTION environment is set to a value determining which type of action is performed.

RPC

In case of RPC, action scripts are implemented as notifications. Once CRIU service wants to execute a script, it sends an RPC message to the caller and waits for it to respond with criu_req message having notify_success = true.

Library

When using a library, one can set up a callback using the criu_set_notify_cb routine.