Aleksa Sarai <asarai@xxxxxxx> wrote: > >> The reason I think this is necessary is that the kernel has no idea > >> how to direct upcalls to what userspace considers to be a container - > >> current Linux practice appears to make a "container" just an > >> arbitrarily chosen junction of namespaces, control groups and files, > >> which may be changed individually within the "container". > > Just want to point out that if the kernel APIs for containers massively > change, then the OCI will have to completely rework how we describe containers > (and so will all existing runtimes). > > Not to mention that while I don't like how hard it is (from a runtime > perspective) to actually set up a container securely, there are undoubtedly > benefits to having namespaces split out. The network namespace being separate > means that in certain contexts you actually don't want to create a new network > namespace when creating a container. Yep, I quite agree. However, certain things need to be made per-net namespace that *aren't*. DNS results, for instance. As an example, I could set up a client machine with two ethernet ports, set up two DNS+NFS servers, each of which think they're called "foo.bar" and attach each server to a different port on the client machine. Then I could create a pair of containers on the client machine and route the network in each container to a different port. Now there's a problem because the names of the cached DNS records for each port overlap. Further, the NFS idmapper needs to be able to direct its calls to the appropriate network. > I had some ideas about how you could implement bridging in userspace (as an > unprivileged user, for rootless containers) but if you can't join namespaces > individually then such a setup is not practically possible. I'm not proposing to take away the ability to arbitrarily set the namespaces in a container. I haven't implemented it yet, but it was on the to-do list: (7) Directly set a container's namespaces to allow cross-container sharing. David -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html