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Re: [scl.org] Image naming for centos-based images



On Thu, Oct 22, 2015 at 1:19 PM, Petr Pisar <ppisar redhat com> wrote:
On Thu, Oct 22, 2015 at 01:03:27PM +0200, Honza Horak wrote:
> I expect we want the centos-based images be run everywhere, not only centos,
> but on Fedora, Debian or even Windows if possible.
>
Impossible. Docker image is archived file system without kernel. The archived
executables depend on kernel ABI.

Folks running highly optimised C/C++/FORTRANĀ  applications may care about the exact kernel version, but that's not your typical containerised application.

When language runtimes are written to be portable across Windows, Linux and Mac OS X, the differences between Linux kernel versions generally vanish into the noise, so if a Java/Python/Ruby/Node.js container crashes because you ran it on a different kernel, that's an extreme edge case.

Even when there *are* ABI compatibility issues, if an app is designed to be failure tolerant, bugs in the *app itself* are still far more likely to be the culprit for a server 500 error than a kernel ABI incompatibility - web services are expected to be crashy bugfests, which is why we still mainly use them for cases where relatively high failure rates (regardless of cause) are an acceptable outcome.

Honza's suggestion of making the three levels of tagging (ruby, ruby-22, ruby-22-centos7) available makes sense to me, as that puts the control in the hands of the end user - when "centos/ruby-22" switches to "centos/ruby-22-centos8", folks will be able to see the userland has changed, even though it will likely still work with a centos7 kernel.

Cheers,
Nick.

--
Nick Coghlan
Fedora Environments & Stacks
Red Hat Developer Experience, Brisbane

Software Development Workflow Designer & Process Architect


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