[CentOS-devel] Question about generating a spin of CentOS 7

Steven Falco sfalco at imaginecommunications.com
Thu Oct 30 17:00:57 UTC 2014

On 10/30/2014 11:51 AM, Jim Perrin wrote:
> On 10/30/2014 10:28 AM, Steven Falco wrote:
>> On 10/30/2014 10:59 AM, Jim Perrin wrote:
>>> On 10/28/2014 10:49 AM, Steven Falco wrote:
>>>> I am interested in generating a spin of CentOS 7, but I'm
>>>> having trouble identifying the correct tool to compose an
>>>> ISO image.
>>> For what reason? Is this something that would benefit others
>>> (could/Should it be a sig?)
>> I have been asked to create a customized install DVD that
>> would automatically install - i.e. use a custom kickstart
>> file.  To do that, I would add the ks file to the isolinux
>> directory, and patch isolinux.cfg to pass my ks file to
>> anaconda via the kernel cmd line.
>> I can do that manually by manipulating the official iso file.
>> It is a lengthy series of steps, extracting the squashfs.img
>> file, then the rootfs.img, then making my changes, and finally
>> putting everything back together.  In short, a total kludge. :-)
> Sounds mostly like the officially documented procedure from 4/5/6 that's
> been in place for a while. In my opinion it's a terrible way to do
> things, and I much prefer pxe and networked installs as you get updates,
> avoid rebuilding media, etc.

You mention 4/5/6, but I'm trying to do this with 7, which I gather
has not been documented yet, based on your comments below.  I'll
follow your suggestion and get in touch with the folks on the
docs list to see if there is a way I can help out.

As to pxe / network, I agree that that is better in most cases, and
while I can do that locally, it would be impossible with remote sites
that lack decent connectivity.  They will need physical media.

Regarding mkisofs, I think there has to be more to it than that.  For
example, something has to create the LiveOS filesystem, before the
DVD image can be created by mkisofs.  That is the part I'm hunting for.

>> Instead, I'd like to be able to reproduce the method by which
>> the official iso file is constructed.  I'd want to be able to
>> do that on my local machine rather than using any CentOS
>> resources, because I don't think this particular spin would be
>> of any interest to the community.  However, the method of
>> generating a custom DVD probably would be of interest to a lot
>> of people.
>> I've actually made a fair amount of progress in the last
>> few days.  First, I used pungi to reconstruct a Fedora 20
>> iso which taught me how that process works.  It also gave
>> me a good log file of a successful pungi build.
>> Then, I tried making that same process work on CentOS 7.  I
>> ran into some issues, because the c7 kernel doesn't include
>> HFSPLUS support (which is needed by isohybrid - long story).
>> I hacked around that by modifying some parts of pungi and lorax
>> to remove the HFSPLUS requirement.  I am also exploring building
>> the HFSPLUS kernel module, so I don't have to hack up pungi / lorax.
>> But back to my question to this list.  Are the pungi and lorax
>> tools part of the official CentOS build process?  If so, then
>> I assume there must be customized version of them, given the
>> problems I saw with HFSPLUS.
> As I said, no. They're not used for the install isos currently.
>> If different tools are used instead of pungi / lorax, then what
>> are those tools?  Are they documented?  Can I help with the
>> documentation of them?
> As I said, the install media is currently done via mkisofs. I don't
> believe it's currently documented. The comps data is on git.centos.org,
> along with the kickstarts for the live media.
> You're certainly welcome to create documentation. If you request access
> on the -docs list with your proposal, the people who oversee wiki access
> will work with you.

A: Because it makes the logic of the discussion difficult to follow.
Q: Why shouldn't I top post?
A: No.
Q: Should I top post?

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