[kata-dev] moby PRs for running DinD with kata

Peng Tao tao.peng at linux.alibaba.com
Thu Sep 19 02:17:47 UTC 2019



On 2019/9/19 00:12, Fox, Kevin M via kata-dev wrote:
> Please don't take this the wrong way, as I like/use Kata. There are other isolated runtimes besides Kata though. gVisor comes to mind. I have heard of at least one other a while back not from the Kata linage. Does this dev separation work with them too? That may make it more palatable to be accepted.
Both [1] and [2] work with different isolated runtimes. The difference 
between them is that [1] requires users to change their docker 
commandline options, while [2] requires to change both commandline 
options and the image.

Akihiro, is it possible for docker daemon to have a new configure option 
instead? Something like:

   "runtimes": {
     "kata": {
       "path": "kata-runtime",
       "privileged_without_host_devices": true
     }
   }

Then the behavior aligns well with [3]. And admins can just add it when 
configuring docker to use kata-runtime. Then users don't need to change 
their docker commandline options. Since the option is useful to all 
docker+kata users, it makes sense to put it in the daemon config.

Cheers,
Tao

> 
> Thanks,
> Kevin
> ________________________________________
> From: Akihiro Suda [akihiro.suda.cz at hco.ntt.co.jp]
> Sent: Tuesday, September 17, 2019 6:35 PM
> To: eric.ernst at intel.com; 'Peng Tao'
> Cc: suda.kyoto at gmail.com; 'kata-dev'
> Subject: Re: [kata-dev] moby PRs for running DinD with kata
> 
> Hi Tao and Eric,
> Cc: my gmail
> 
> 
>> I agree with the sentiment that privileged shouldn't be used unless
>> actually necessary, which Akihirio showed isn't the case.
>> FWICS, [2] doesn't work with runc, and is Kata specific?
> 
> [2] doesn't work with runc and is mostly specific to Kata.
> Anyway [1] also seems specific to Kata, and doesn't seem to have any valid usecase with runc.
> 
> Regards,
> Akihiro Suda
> 
> -----Original Message-----
> From: eric.ernst at intel.com [mailto:eric.ernst at intel.com]
> Sent: Wednesday, September 18, 2019 1:09 AM
> To: Peng Tao
> Cc: kata-dev; Akihiro Suda; Xu Wang
> Subject: Re: moby PRs for running DinD with kata
> 
> Hey Tao,
> 
> On Tue, Sep 17, 2019 at 11:42:20PM +0800, Peng Tao wrote:
>> Hi Kata developers/maintainers/AC members,
>>
>> Since I cannot attend the AC meeting today, I want to bring to your
>> attention about two mody PRs([1] and [2]).
> 
> FWIW, I like using the ML for these kinds of discussions, anyway, since
> it allows for more folks to chime in, and some digestion of the issue as
> well.  Thanks for putting this on ML!
> 
>>
>> Akihiro Suda developed both of them as fixes for running DinD with
>> kata (aka, docker in kata). [1] is to provide a new docker security
>> option --privileged-without-host-devices, similar to the fix we had
>> with containerd [1]. And [2] is to simply fix the DinD entrypoint.sh
>> to remount sysfs in rw mode, and use a bunch of specific options to
>> tell docker to give proper permissions to DinD container.
> 
> Thanks Akihiro.
> 
>>
>> While [2] is good enough to fix DinD with kata, I'm afraid there might
>> be other container images out there that require similar tweaks to
>> work.
> 
> 
> I agree with the sentiment that privileged shouldn't be used unless
> actually necessary, which Akihirio showed isn't the case.
> FWICS, [2] doesn't work with runc, and is Kata specific?
> 
> This is probably fine for users who "know what they are doing," and
> are running just in Kata? Maybe there should be a DiK or DinK image?
> 
>> So I'd like to ask for your opinions on this. Do you think [2]
>> is good enough or is it better to persuade moby maintainers to go with
>> [1] instead?
>>
> 
> I'm glad this is fixed already in containderd (and on its way for
> cri-o). I think adding a new flag would be helpful for us, but I
> understand this may not be acceptable from a moby maintainer pov.
> Changing the behavior of existing is too difficult for end-users, and
> i'm not sure an equivalent of [3] is feasilbe either.
> 
> What do others think?
> 
> -Eric
> 
> 
> 
>> Cheers,
>> Tao
>>
>> - [1] https://protect2.fireeye.com/url?k=82cd4273-de787dca-82cd6866-0cc47adc5fce-b70c583d0228b90b&q=1&u=https%3A%2F%2Fgithub.com%2Fmoby%2Fmoby%2Fpull%2F39702
>> - [2] https://protect2.fireeye.com/url?k=44cf4bd5-187a746c-44cf61c0-0cc47adc5fce-d0e67658ad4ffff0&q=1&u=https%3A%2F%2Fgithub.com%2Fdocker-library%2Fdocker%2Fpull%2F191
>> - [3] https://protect2.fireeye.com/url?k=bda7b490-e1128b29-bda79e85-0cc47adc5fce-3601f0663a93c4fe&q=1&u=https%3A%2F%2Fgithub.com%2Fcontainerd%2Fcri%2Fpull%2F1225
>>
>> --
>> Into something rich and strange.
> 
> 
> 
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-- 
Into something rich and strange.



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