On 25/08/20 12:05 am, Dmitry Tantsur wrote:
On Mon, Aug 24, 2020 at 1:52 PM Sean Mooney <smooney@redhat.com <mailto:smooney@redhat.com>> wrote:
On Mon, 2020-08-24 at 10:32 +0200, Dmitry Tantsur wrote: > Hi, > > On Mon, Aug 24, 2020 at 10:24 AM Arne Wiebalck <arne.wiebalck@cern.ch <mailto:arne.wiebalck@cern.ch>> > wrote: > > > Hi! > > > > CERN's deployment is using the iscsi deploy interface since we started > > with Ironic a couple of years ago (and we installed around 5000 nodes > > with it by now). The reason we chose it at the time was simplicity: we > > did not (and still do not) have a Swift backend to Glance, and the iscsi > > interface provided a straightforward alternative. > > > > While we have not seen obscure bugs/issues with it, I can certainly back > > the scalability issues mentioned by Dmitry: the tunneling of the images > > through the controllers can create issues when deploying hundreds of > > nodes at the same time. The security of the iscsi interface is less of a > > concern in our specific environment. > > > > So, why did we not move to direct (yet)? In addition to the lack of > > Swift, mostly since iscsi works for us and the scalability issues were > > not that much of a burning problem ... so we focused on other things :) > > > > Here are some thoughts/suggestions for this discussion: > > > > How would 'direct' work with other Glance backends (like Ceph/RBD in our > > case)? If using direct requires to duplicate images from Glance to > > Ironic (or somewhere else) to be served, I think this would be an > > argument against deprecating iscsi. > > > > With image_download_source=http ironic will download the image to the > conductor to be able serve it to the node. Which is exactly what the iscsi > is doing, so not much of a change for you (except for s/iSCSI/HTTP/ as a > means of serving the image). > > Would it be an option for you to test direct deploy with > image_download_source=http? i think if there is still an option to not force deployemnt to altere any of there other sevices this is likely ok but i think the onious shoudl be on the ironic and ooo teams to ensure there is an upgrade path for those useres before this deprecation becomes a removal without deploying swift or a swift compatibale api e.g. RadosGW
Swift is NOT a requirement (nor is RadosGW) when image_download_source=http is used. Any glance backend (or no glance at all) will work.
Even though the TripleO undercloud has swift, I'd be inclined to do image_download_source=http so that it can scale out to minions, and so we're not relying on a single-node swift for image serving