Re: [libvirt] [PATCHv5 1/5] domifaddr: Implement the public APIs

On 04/09/13 03:13, Eric Blake wrote: >On 09/03/2013 01:07 PM, Eric Blake wrote: >>On 09/01/2013 07:43 AM, Nehal J Wani wrote: >>>Define a new API virDomainInterfaceAddresses, which returns >>>the address information of a running domain's interfaces(s). >>>If no interface name is specified, it returns the information >>>of all interfaces, otherwise it only returns the information >>>of the specificed interface. The address information includes >>>the MAC and IP addresses. >>> >>>Define helper function virDomainInterfaceFree, which allows >>>the upper layer application to free the domain interface object >>>conveniently. >>> >>>The API is going to provide multiple methods by flags, e.g. >>> >>> * Query guest agent >>> * Parse lease file of dnsmasq >>> * DHCP snooping >>> >>>But at this stage, it will only work with guest agent, and flags >>>won't be supported. >>That worries me a bit. Ultimately, we want our interfaces to behave as >>sane as possible when flags==0; rather than making the behavior be that >>'flags==0' implies 'only guest agent probe', I'd rather introduce a flag >>right away up front that says 'include guest agent probe in the set of >>attempted methods', and then document that 'flags==0 is shorthand for >>letting the hypervisor choose the best method(s) out of supported >>possibilities)'. In other words, I want to make sure that this API will >>be similar to virDomainShutdownFlags, where a flags of 0 lets the >>hypervisor choose between methods, a single explicit flag forces the >>hypervisor to use that method alone, and more than one flag can be OR'd >>together to let the hypervisor choose among that subset of flags. >Hmm. I'm replying to myself - is that a good sign? > >If the guest agent returns names that are provided by the guest, and >don't necessarily correspond to the domain XML, then maybe it's best to >NEVER return guest results by default, but to make the user always >explicitly request agent interaction. Hm, yes, the MAC address returned by guest agent might not match what the domain config specifies. It reminds me something, both the leases file and snooping will returns the interface name like "vnetN", which is different with what guest agent returns (like ethN or emN). And since the MAC address from guest agent might be different with what domain config specifies, we have no way to convert it into the names in domain config. That says we will have different name styles for guest agent and the other two methods, which will need quite documentations to explain.