On Tue, 2017-05-23 at 10:17 -0500, Eric W. Biederman wrote: > David Howells <dhowells@xxxxxxxxxx> writes: > > Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote: > > > It does solve this in userspace rather simply. > > > > Ummm... How? The kernel DNS resolver is not namespace aware. > > But it works fine if called in the proper context and we have a > defacto standard for where to put all of the files (the tricky part) > if you are dealing with multiple network namespaces simultaneously. I think you're missing each other's points slightly. What David is pointing out is that the kernel has a DNS cache (net/dns_resolver/) it can do name to IP translations, but isn't namespaced. Once it has one entry all containers would see it if they cause a lookup to go through the kernel cache, so going through the cache you can't have a name resolving to different IP addresses on a per container basis. I think Eric's point is that if you need the same DNS names resolving to different IP addresses on a per container basis, you can do this in userspace today but you have to disable the in-kernel DNS cache. James
