Hi, On Mon, Mar 23, 2020 at 09:48:52AM -0500, Ryan Harper wrote: > On Mon, Mar 16, 2020 at 8:44 AM Slawek Kaplonski <[email protected]> > wrote: > > > Hi, > > > > > On 11 Mar 2020, at 20:13, Ryan Harper <[email protected]> wrote: > > > > > > > > > > > > On Wed, Mar 11, 2020 at 4:39 AM Slawek Kaplonski <[email protected]> > > wrote: > > > Hi, > > > > > > Hi Slawek, > > > > > > Thanks for reaching out to the cloud-init community. > > > > > > > > > I’m OpenStack Neutron developer. Since some time we have proposed spec > > [1] about Metadata over IPv6 in IPv6 only networks. > > > This spec proposes to use fe80::a9fe:a9fe IP address as it is equivalent > > of 169.254.169.254 in IPv6 link-local subnet. > > > > > > According to [2] I know already that cloud-init can be configured to use > > any metadata urls with “metadata_urls” so we can use such IPv6 address (or > > any other) and can be configured to be used in cloud-init on guest vms. > > > But as cloud-init is one of the biggest users of Metadata service, I > > would like to ask cloud-init community what do You think about it and if > > this will work for You. > > > Any feedback here or in the spec's review will be appreciated :) > > > > > > Some initial thoughts and questions: > > > > > > - In what order should cloud-init try ipv6 and ipv4? > > > - cloud-init would prefer to know which one it should use so we don't > > timeout on an endpoint that isn't there. > > > > I would say that it it could be checked what IP addresses are configured > > in the guest OS already and use correct one if only one type of addresses > > is there. If there would be both IPv4 and IPv6, it could try IPv4 first as > > it is like that now. What do You think about such solution? > > > > cloud-init runs before networking comes up. In OpenStack, cloud-init will > to an Ephemeral DHCP to try to reach metadata service over IPV4. Once > metadata service is crawled, cloud-init will write out network > configuration obtained from metadata service. > Currently we will try a list of URLs/IPs as configured in the datasource. > We can add the IPv6 metadata url to the list, my question is where in the > list should it go? If we put it first, then on deployments which lack IPv6 > metadata service, all VMs will pay a > boot speed cost of trying to fetch metadata from a non-existent URL. If > the v6 address is at the end, then IPv6-only deployments will waste time > trying to hit an IPv4 url which is not present. This is why I'm interested > in being "told" in some way.
But this would still be better than it is now where in IPv6 only environment cloud-init now is wasting time trying to reach metadata service over IPv4 and finally failing :) So IMO this can be something like first step at least (or what Bence proposed with new Datasource) > This knowledge would need to come from a non-network area. Typically this > is done via DMI tables; however, DMI is not a complete solution as this is > not available on all architectures (s390x and ppc64le and some arm64), > which makes this > sub-optimal. > > > > > - > > > - cloud-init's EphemeralDHCP code currently relies upon dhclient and > > ipv4 ips/routes; this will need updating to work with v6; what is needed > > use fe80::a9fe:a9fe ? > > > > As this is link local IP address it should be reachable without any > > configuration if IPv6 is enabled on the interface in the guest. > > > > OK. That makes the v6 support simpler. > > > > > - is there a chance that Metadata is available over either v4 or v6? > > > - would the data ever diverge? > > > > I don’t know if this data can diverge in the future. > > > > Reading the spec, it appeared to me that the metadata service has no > changes, rather this was more about configuring which network ports expose > the service. > I would not expect there to be a different metadata service on v4 from v6 > (the instance-id is the same either path); > > > > > > > > > > > Thanks, > > > Ryan Harper > > > > > > > — > > Slawek Kaplonski > > Senior software engineer > > Red Hat > > > > -- Slawek Kaplonski Senior software engineer Red Hat -- Mailing list: https://launchpad.net/~cloud-init Post to : [email protected] Unsubscribe : https://launchpad.net/~cloud-init More help : https://help.launchpad.net/ListHelp
