Re: [libvirt] [PATCH] RFC: Introduce new domain create APIs to pass pre-opened FDs to LXC

From: "Daniel P. Berrange" <berrange(a)redhat.com&gt; With container based virt, it is useful to be able to pass pre-opened file descriptors to the container init process. This allows for containers to be auto-activated from incoming socket connections, passing the active socket into the container. To do this, introduce a pair of new APIs, virDomainCreateXMLWithFiles and virDomainCreateWithFiles, which accept an array of file descriptors. For the LXC driver, UNIX file descriptor passing will be used to send them to libvirtd, which will them pass them down to libvirt_lxc, which will then pass them to the container init process. This will only be implemented for LXC right now, but the design is generic enough it could work with other hypervisors, hence I suggest adding this to libvirt.so, rather than libvirt-lxc.so

/** + * virDomainCreateXMLWithFiles: + * @conn: pointer to the hypervisor connection + * @xmlDesc: string containing an XML description of the domain + * @nfiles: number of file descriptors passed + * @files: list of file descriptors passed + * @flags: bitwise-OR of supported virDomainCreateFlags + * + * Launch a new guest domain, based on an XML description similar + * to the one returned by virDomainGetXMLDesc() + * This function may require privileged access to the hypervisor. + * The domain is not persistent, so its definition will disappear when it + * is destroyed, or if the host is restarted (see virDomainDefineXML() to + * define persistent domains). + * + * @files provides an array of file descriptors which will be + * made available to the 'init' process of the guest. This is + * only supported for guests which use container based virtualization + * technology.