what will be impacted for compiling code in different kernel in docker?

Can I trust the builds in docker container for redhat6.4 in Ubuntu 14.04 host for c/c++ source codes ? or any limitation I need to consider ?

We are trying to use docker to serve different OS platform to compile the source codes, since technology in docker is share the host os’s kernel, see related question What is the relationship between the docker host OS and the container base image OS?

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    • My host OS is ubuntu 14.04 (easy to install docker), kernel is 3.13.0-24-generic
    • My application platform is redhat 6.4 (kernel is 2.6.32-358.el6.x86_64)

    When I created the container for RHEL for Ubuntu, the kernel is updated to 3.13.0-24-generic as well.

    My application is c/c++ & java based.

    I don’t think java will be any problem for the compiled .jar files since it is based on jvm.

    And for c/c++ codes, mostly I understand it depends on libc kind of shared library, not depends on kernel, so is it possible to use this compiled codes into real redhat environment.

    This setup is used for development only, not for production, the generated binary files are supposed to be installed real standalone machines with RHEL or VM.

    So any things I need to consider ?

    Probably it is more lxc related question.

    Updated to add some sample

    I download the gameoflife codes https://github.com/rvsjoen/game-of-life, and compiled in both system, looks for this case since md5 is the same, the result is the same and it is trustable.

    This is redhat 6.4 system in VM

    [root@redhat game-of-life-master]# cat /etc/redhat-release
    Red Hat Enterprise Linux Server release 6.4 (Santiago)
    [root@redhat game-of-life-master]# uname -a
    Linux redhat 2.6.32-358.el6.x86_64 #1 SMP Tue Jan 29 11:47:41 EST 2013 x86_64 x86_64x86_64 GNU/Linux
    [root@redhat]# ldd gol
        linux-vdso.so.1 =>  (0x00007fffaeaa8000)
        libncurses.so.5 => /lib64/libncurses.so.5 (0x00000033fa000000)
        libc.so.6 => /lib64/libc.so.6 (0x00000033f9c00000)
        libtinfo.so.5 => /lib64/libtinfo.so.5 (0x00000033fb800000)
        libdl.so.2 => /lib64/libdl.so.2 (0x00000033f9800000)
        /lib64/ld-linux-x86-64.so.2 (0x00000033f9400000)
    [root@redhat]# md5sum gol
    4f3245d3d61b1c73e48537dd612d37c3  gol
    

    And this is redhat in docker container

    bash-4.1# cat /etc/redhat-release
    Red Hat Enterprise Linux Server release 6.4 (Santiago)
    bash-4.1# uname -a
    Linux f51c7b4e80aa 3.13.0-24-generic #46-Ubuntu SMP Thu Apr 10 19:11:08 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
    bash-4.1# ldd gol
        linux-vdso.so.1 =>  (0x00007fff5e3c2000)
        libncurses.so.5 => /lib64/libncurses.so.5 (0x00007f2e84863000)
        libc.so.6 => /lib64/libc.so.6 (0x00007f2e844d0000)
        libtinfo.so.5 => /lib64/libtinfo.so.5 (0x00007f2e842ae000)
        libdl.so.2 => /lib64/libdl.so.2 (0x00007f2e840aa000)
        /lib64/ld-linux-x86-64.so.2 (0x00007f2e84a8e000)
    bash-4.1# md5sum gol
    4f3245d3d61b1c73e48537dd612d37c3  gol
    

    Are there any exception for c/c++ codes ?

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  • One Solution collect form web for “what will be impacted for compiling code in different kernel in docker?”

    There is, in normal situations, no exception for natively compiled codes (C, C++…).

    As you wrote, programs interact with the libc, not the kernel, except very special situations.

    This libclibrary is not shared between your Ubuntu host and your Redhat container. Your container has its own libcthat abstracts system calls to the kernel.

    About the kernel itself, note the even if the Linux kernel internals tend to be moving, always evolving pieces of code, what is publicly exposed (the ABI, accessible to userspace applications and libc) is kept stable and compatible between releases. In rare occasions this compatibility has been broken, most of the time, not intentionally. (see this article).

    So, yes, it is perfectly safe to have use a RHEL dev. environment on an Ubuntu host, and to trust the builds generated from this container.

    Docker will be the best open platform for developers and sysadmins to build, ship, and run distributed applications.