[libvirt] [PATCH] [0/6] implement synchronous hook scripts

As discussed previously this implement hook scripts which may be called from libvirtd at specific times. The script are supposed to be small, execute fast as it's synchronous, their exit value is 0 otherwise it's considered a failure (which may be ignored but in general will stops the ongoing operation). Scripts are stored under /etc/libvirt/hook/ (or rather $SYSCONF_DIR/libvirt/hook/) if missing no script invocation will ever be done. There is one script per 'driver' there is currently hooks for the daemon, qemu and lxc, so right now only /etc/libvirt/hook/daemon /etc/libvirt/hook/qemu /etc/libvirt/hook/lxc are potentially used. The implemented set of operations is rather simple currently daemon start, reload, and exit, and for domain operations, domain startup and exit. This can be extended to more drivers in the future of more fine-grained modularity for the scripts. The current API to the script israther simple it get passed arguments about the object name, the operation name, suboperation, and an extra string. Right now for the daemon the script would get the fallowing calls: /etc/libvirt/hooks/daemon - start - start /etc/libvirt/hooks/daemon - reload begin SIGHUP /etc/libvirt/hooks/daemon - shutdown - shutdown and for qemu (or lxc): /etc/libvirt/hooks/qemu RHEL-5.4-64 start begin - /etc/libvirt/hooks/qemu RHEL-5.4-64 stopped end - with the XML configuration of the domain passed on the script stdin if needed. In case of script failure at domain startup, this is raised as an normal error, e.g.: [root@paphio tmp]# virsh start RHEL-5.4-64 error: Failed to start domain RHEL-5.4-64 error: Hook script execution failed: Hook script /etc/libvirt/hooks/qemu qemu failed with error code 256:forbidden startup [root@paphio tmp]# Some hooks could certainly be added at different place in domain lifetime operations, for example we plan to add some for migration, but one thing to remember is that those synchronous scripts can have a serious impact on execution, so to some extend it's better to use the asynchronous async event mechanism when possible. Among the things left to improve and check, there is the behaviour when the daemon is started by the user for example for qemu:///user and double check some of the script interaction with security, SELinux in particular. But the basics are there, and I would hope to have this in the next release, Daniel -- Daniel Veillard | libxml Gnome XML XSLT toolkit http://xmlsoft.org/ daniel(a)veillard.com | Rpmfind RPM search engine http://rpmfind.net/ http://veillard.com/ | virtualization library http://libvirt.org/