Re: piping core dump to a program escapes container

Dongsheng Yang
2015-12-09T08:14:49Z

On 12/09/2015 02:32 PM, Eric W. Biederman wrote:
> Dongsheng Yang <yangds.fnst@cn.fujitsu.com> writes:
>
>> On 12/09/2015 11:29 AM, Eric W. Biederman wrote:
>>> Dongsheng Yang <yangds.fnst@cn.fujitsu.com> writes:
>>>
>> [...]
>>
>>> There has not yet been an obvious namespace in which to stick
>>> core_pattern, and even worse exactly how to appropriate launch a process
>>> in a container has not been figured out.
>>>
>>> If those tricky problems can be solved we can have a core_pattern in a
>>> container. What we have now is the best we have been able to figure out
>>> so far.
>>
>> Thanx Eric, but if I want to make docker works rely on this behaviour,
>> is that reliable?
>>
>> I mean, I want to make a docker container to dump the
>> core file to a specified path in host by a pipe way. But I am afraid
>> this behaviour would be changed later. Any suggestion?
>
> The kernel rules say if there is a behavior someone depends on and that
> behavior changes and breaks userspace that is a regression and it is not
> allowed.
>
> As developers we try not to create regressions. But some days it
> requires someone testing/using the functional enough to catdch an issue.
>
> That said the real issue you are likely to run into when developing this
> as part of docker is that docker doesn't get to own the core pattern.
> It doesn't make sense for any one application to, as it is a kernel wide
> setting.

Agreed.
> To have different app or container specific policies for core
> dumping likely requires either solving the problems I mentioned with
> containers or in userspace a solution so there can be an
> /etc/core_pattern.d/ with different configuration and different scripts
> that somehow know how to select which core files they want and dump them
> sanely.

We would try to solve the problems you mentioned, but sound not easy.
Anyway, I need to read some old discussion at first I think.

Thanx
Yang
>
> Eric
>
>
>