Re: Odd uuid-ossp behavior on smew and shearwater

Josh Kupershmidt <schmiddy(at)gmail(dot)com> writes:
> On Wed, May 28, 2014 at 11:23 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> I've just committed regression test adjustments to prevent that from
>> being a failure case, but I am confused about why it's happening.
>> I wouldn't be surprised at not getting a MAC address on a machine that
>> lacks any internet connection, but that surely can't describe the
>> buildfarm environment. Are you curious enough to poke into it and
>> see what's going on? It might be useful to strace a backend that's
>> trying to execute uuid_generate_v1() and see what the kernel interaction
>> looks like exactly.

> Here's the result of attaching strace to an idle backend, then running
> SELECT uuid_generate_v1(). AFAIR shearwater is a cheaply-hosted OpenVZ
> VPS under the hood.

Interesting. Looks like you have access only to virtual network
interfaces, and they report all-zero MAC addresses, which the UUID library
is smart enough to ignore. If smew is also in a virtual environment
then that's probably the explanation. (There are some other buildfarm
critters that are reporting MAC addresses with the local-admin bit set,
which I suspect also means they've got virtual network interfaces, but
with a different treatment of the what-to-report problem.)

regards, tom lane