On 01/27/2012 10:22 AM, Peter Krempa wrote:
> This patch adds a new command "desc" to show and modify titles and
> description for the domains using the new API.
Are your plans to have "desc" also modify metadata, or would that be
better suited to a new command, probably named "metadata"?
>
> This patch also adds a new flag for the "list" command to show titles in
> the domain list, to allow easy identification of VMs by storing a short
> description.
>
> Example:
> virsh # list --title
> Id Name State Title
> -----------------------------------------------
> 0 Domain-0 running Mailserver 1
> 2 fedora paused
> ---
> +/* extract description or title from domain xml */
> +static char *
> +vshGetDomainDescription(vshControl *ctl, virDomainPtr dom, bool title,
> + unsigned int flags)
> +{
> + char *desc = NULL;
> + char *domxml = NULL;
> + virErrorPtr err = NULL;
> + xmlDocPtr doc = NULL;
> + xmlXPathContextPtr ctxt = NULL;
> + int type;
> +
> + if (title)
> + type = VIR_DOMAIN_METADATA_TITLE;
> + else
> + type = VIR_DOMAIN_METADATA_DESCRIPTION;
> +
> + if ((desc = virDomainGetMetadata(dom, type, NULL, flags))) {
> + return desc;
> + } else {
> + err = virGetLastError();
> +
> + if (err && err->code == VIR_ERR_NO_DOMAIN_METADATA) {
Ah, so we are using the new error (hmm, I should re-read the description
- we even documented it that way).
> + desc = vshStrdup(ctl, "");
> + virResetLastError();
> + return desc;
> + }
> +
> + if (err && err->code != VIR_ERR_NO_SUPPORT)
> + return desc;
> + }
> +
> + /* fall back to xml */
> + /* get domains xml description and extract the title/description */
> + if (!(domxml = virDomainGetXMLDesc(dom, flags))) {
> + vshError(ctl, "%s", _("Failed to retrieve domain XML"));
> + goto cleanup;
> + }
> + doc = virXMLParseStringCtxt(domxml, _("(domain_definition)"), &ctxt);
> + if (!doc) {
> + vshError(ctl, "%s", _("Couldn't parse domain XML"));
> + goto cleanup;
> + }
> + if (title)
> + desc = virXPathString("string(./title[1])", ctxt);
> + else
> + desc = virXPathString("string(./description[1])", ctxt);
> +
> + if (!desc)
> + desc = vshStrdup(ctl, "");
Looks like a reasonable use of the API.
> Prints the available amount of memory on the machine or within a
> @@ -426,6 +435,29 @@ Define a domain from an XML <file>. The domain definition is registered
> but not started. If domain is already running, the changes will take
> effect on the next boot.
>
> +=item B<desc> [I<--live> | I<--config>] [I<--title>] [I<--edit>]
> + [I<--new-desc> New description or note message]
> +
> +Show or modify description and note for a domain. These values are user
> +fields that allow to store arbitrary textual data to allow easy identifiaction
> +of domains. Note is a short (maximum 40 characters) field.
Again, careful with the wording. We may want to s/note/title/ to match
the XML, and be careful in describing the differences between them.
I think this patch is mostly there; but may have more fallout if we make
any more tweaks to the public API or description of it. I'm okay if we
save <metadata> manipulation from virsh for another day.
--
Eric Blake eblake@xxxxxxxxxx +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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