[libvirt] [RFC]: Snapshot API

Hello, As some of you know, I've been working on a new snapshot API. This API is heavily based on DanB's earlier API proposed here: https://www.redhat.com/archives/libvir-list/2010-January/msg00626.html I've made some modifications to make it more libvirt-ish, and to add a couple of features I think it lacked. The full documentation is below. Any comments are appreciated. /* NOTE: struct _virDomainSnapshot is a private structure, ala * struct _virDomain. */ typedef struct _virDomainSnapshot virDomainSnapshot; /* Take a snapshot of the current VM state */ virDomainSnapshotPtr virDomainSnapshotCreateXML(virDomainPtr domain, const char *xmlDesc, unsigned int flags); /* Dump the XML of a snapshot */ /* NOTE: see below for proposed XML */ char *virDomainSnapshotGetXMLDesc(virDomainSnapshotPtr snapshot, unsigned int flags); /* Return the number of snapshots for this domain */ int virDomainSnapshotNum(virDomainPtr domain, unsigned int flags); /* Get the names of all snapshots for this domain */ int virDomainListSnapshotNames(virDomainPtr domain, char **names, int nameslen, unsigned int flags); /* Get a handle to a named snapshot */ virDomainSnapshotPtr virDomainSnapshotLookupByName(virDomainPtr domain, const char *name, unsigned int flags); /* Set this snapshot as the current one for a domain, to be * used next time domain is started */ int virDomainSnapshotActivate(virDomainSnapshotPtr snapshot, unsigned int flags); /* Deactivate a snapshot - with no flags, the snapshot is not used anymore, * but also not removed. With a MERGE flag, it merges the snapshot into * the base image. With a DISCARD flag, it deletes the snapshot. MERGE * and DISCARD are mutually-exclusive. Note that this operation can * generally only happen when the domain is shut down, though this is * hypervisor-specific */ typedef enum { VIR_DOMAIN_SNAPSHOT_DEACTIVATE_MERGE, VIR_DOMAIN_SNAPSHOT_DEACTIVATE_DISCARD, } virDomainSnapshotDeactivate; int virDomainSnapshotDeactivate(virDomainSnapshotPtr snapshot, unsigned int flags); int virDomainSnapshotFree(virDomainSnapshotPtr snapshot); NOTE: During snapshot creation, *none* of the fields are required. That is, you can call virDomainSnapshotCreateXML() with an XML of "<domainsnapshot/>". In this case, the individual driver will make up a <name> for you, the <creationdate> will be set to the current time+date, <description> will be empty, <state> will be "off", <compression> will be empty, and <parent> will be empty. If you do want to specify some fields during virDomainSnapshotCreateXML(), note that the only ones that are settable are <name>, <description>, <compression>, and <parent>; the rest are ignored, and filled in by the driver when the snapshot is actually created. NOTE: <parent> is used to create "trees" of snapshots, and may or may not be supported by individual hypervisor implementations. If <parent> is specified and the underlying hypervisor does not support it, an error will be thrown. NOTE: <compression> is used to compress snapshots, and may or may not be supported by individual hypervisor implementations. If <compression> is specified and the underlying hypervisor does not support it, an error will be thrown. <domainsnapshot> <name>XYZ</name> <creationdate>...</creationdate> <description> ....blah.... </description> <state>RUNNING</state> <domain> <uuid>XXXXX-XXXX-XXXX-XXXX-XXXXXXXXX</uuid> </domain> <compression>gzip</compression> <parent> <name>ABC</name> </parent> </domainsnapshot> The virsh commands will be: virsh snapshot-create [--compress] <dom> <xmlfile> virsh snapshot-list <dom> virsh snapshot-dumpxml <dom> <name> virsh snapshot-activate <dom> <snapshotname> virsh snapshot-deactivate <dom> <snapshotname> [--merge|--delete] -- Chris Lalancette