Re: [atomic-devel] Changing /etc/localtime with container images

[Daniel J Walsh <dwalsh redhat com>]

On 12/08/2016 11:04 AM, Frantisek Kluknavsky wrote:
> On 07/12/16 22:14, Daniel J Walsh wrote:
>> The following bugzilla shows a problem with containers.
>>
>> https://bugzilla.redhat.com/show_bug.cgi?id=1399749\\
>>
>> People want to be able to volume mount in /etc/localtime into a
>> container to change its TimeZone.  The problem is the way the kernel
>> handles bind mounting symbolic links
>>
>> On my host I have
>>
>> ls -l /etc/localtime
>>
>> lrwxrwxrwx. 1 root root 38 Dec  7 16:09 /etc/localtime ->
>> ../usr/share/zoneinfo/America/New_York
>>
>> In a Fedora container I have
>>
>> ls -l /etc/localtime
>> lrwxrwxrwx. 1 root root 25 Dec  7 21:08 /etc/localtime ->
>> ../usr/share/zoneinfo/UTC
>>
>> If you run a docker container like
>>
>>
>> docker run -ti -v /etc/localtime:/etc/localtime:ro fedora bash
>>
>>
>> You do not end up with /etc/localtime as a link pointing to New York,
>> You end up with the
>>
>> /usr/share/zoneinfo/New_York file mounted over the
>> /usr/share/zoneinfo/UTC file.
>>
>> IE the mount -o bind command follows both symbolic links.
>>
>> This is causing issues with the java program inside the bugzilla.
>>
>> The proposed fix is to change container images to
>>
>> rm -f /etc/localtime
>>
>> cp /usr/share/zoneinfo/UTC /etc/localtime
>>
>>
>> Then if I do the command above
>>
>> docker run -ti -v /etc/localtime:/etc/localtime:ro fedora bash
>>
>> I end up with the /etc/localtime file inside of the container containing
>> the content of the New_York file.
>>
>> Does anyone object to this idea?
>>
> Hi,
>
> a related question: Once you bind-mount /etc/localtime as a normal file
> (not symlink) from the host, do you still need full /usr/share/zoneinfo?
> The size in uncompressed form is a few megabytes - not completely
> negligible.
>
> Except the obvious inability to change timezones, what else would break?
>
> Have a nice day,
>
> Fero
>
I would be fine with removing them, and requiring them be changed from
the host.

But Only use I know of is to change timezone by modifying the link.