Converting a Docker container to a Runc container -> Read-only file system

[Philip Rhoades]

Aleksa,


On 2019-02-21 19:31, Aleksa Sarai wrote:
> On 2019-02-21, Philip Rhoades <phil at pricom.com.au> wrote:
>> People,
>> 
>> I have exported an existing container with:
> 
> This isn't the right list for this -- I would suggest mailing
> <dev at opencontainers.org>.


Oh, I am on that list too but I thought from the name of this list, it 
would be more appropriate . .


> This is a kernel mailing list -- but I'll
> answer your question anyway.


Thanks!  OK, I will check all of the stuff below later today.

Regards,

Phil.


>>   mkdir rootfs
>>   docker export rails_dsf | tar -C rootfs -xvf -
>>   runc spec
>>   runc run rails_dsf
> 
> Check whether "readonly": true is in config.json, and set it to false 
> if
> it is.
> 
> I would recommend using skopeo and umoci for generating an OCI runtime
> bundle, since those are more modern. The equivalent to the above 
> command
> would be:
> 
>   $ # You need an image to operate on.
>   % id="$(docker commit rails_dsf rails_img)"
> 
>   # Convert the Docker image to an OCI image.
>   % skopeo copy docker-daemon:rails_img:latest oci:rails_img:latest
> 
>   # Unpack the image into an OCI runtime bundle.
>   % umoci unpack --image rails_img:latest bundle
> 
>   # Run the bundle with runc.
>   % runc run -b bundle rails_dsf
> 
> (The nice thing is that you can then generate new layers if you want
> using OCI -- as well as taking advantage of rootless containers if you
> use the --rootless flag to umoci.)



-- 
Philip Rhoades

PO Box 896
Cowra  NSW  2794
Australia
E-mail:  phil at pricom.com.au