[SATLUG] Re: Decision-based ISOs

[Mike Wallace]

> OK, this is going to show my ignorance, so please bear with me.

Hey, we're here to learn from each other.  Always feel free to ask 
questions no matter how ignorant it may sound.  Everyone has to learn 
sometime.

> Why does each ISO have to be re-compiled? If I am thinking correctly, 
> most distros have the applications and kernels already compiled and have 
> some packaging in the installer to "move" the application into the 
> installation, whether during or after full installation. The maintainer 
> would first have each application already optimized for each kernel 
> offering if need be (or simply keep one, like 2.4 or 2.6 if it would 
> prevent further headaches), then the server would simply pull those 
> applications and dependencies as needed from the user's responses then 
> build the ISO from there.
> 
> Basically, why would it need to remain in source?

The ISO isn't really re-compiled per se, but the ISO would need to get 
re-created each time the contents of the CD change.  An ISO file is a 
singular file which contains ALL of the contents of the CD.  If you opt 
to exclude just one file, the ISO would have to get re-created.  If you 
add just one file, the ISO has to get re-created.  The files within the 
ISO image are already compiled for the system.  No re-compilation of the 
packages is happening; the packages themselves are not changing.  What's 
changing is the contents of the ISO.  And it's not necessarily the 
simplest thing to change an ISO after it is created.

Well, come to think of it, I'm not sure that's true.  If I were to mount 
an ISO image directly, would it be possible to change the contents with 
standard commands?  Anyway, it's not very often that I work with CD 
images.  It's probably best for me to defer this to someone in the know 
before I start spreading misinformation.  ;-)

> I do agree with it bogging down the server. Perhaps a two-step process: 
> First, give me what you want in the ISO. I'll send you an email when 
> it's ready to download, probably from a different server than where the 
> submission is made. Intensive, I know.

This is possible, however it's a lot more work than the alternatives. 
If you have a fast internet connection, you can do a minimal install and 
then use yum/apt/whatever to download and install the specific packages 
you need.  For someone with a fast connection, there's really no reason 
to have to create an ISO image with all the packages to begin with. 
Most of my machines have fast connections, so after I do the minimal 
install and get going, the first thing I do is setup /etc/yum.conf, do a 
  'yum update' and then install specific packages that aren't there yet.

There's also the case of wanting ISO images and having a fast internet 
connection.  Maybe you'll be doing a lot of installs and it's be nice to 
not have to hammer your internet connection.  Downloading 2 or 3 CDs 
shouldn't take very long.  Just have something to do while the images 
are downloading.  During the install, there's typically a time when you 
get a number of questions about what to install.  Also, with this 
approach you don't limit yourself -- it could very easily happen that 
sometime later you need package xyz and your custom ISO doesn't have 
package xyz.  That's one other drawback of the custom ISO which excludes 
stuff -- you may need some of that stuff one day.

Now for the case of a slow connection, it would be nice to download as 
little data as possible.  In this case, you could download a minimal CD 
with only the core packages (this will probably take a while).  After 
the minimal install, use yum/apt/whatever to install only the specific 
packages you need.  There's really no difference between this method and 
downloading a custom ISO.  In the end, you're still downloading the same 
amount of data.

So, while it might be an interesting exercise to download custom ISO 
images, there's really no real need to do this.  Also, the servers out 
there only need to serve the ISO images and/or repository packages. 
Whatever you need, you can get.  Creating custom ISOs would place a lot 
more burden on the servers, and why would someone out there buy a more 
expensive machine only to accommodate something that could be duplicated 
by the end user?

Once you're in the world of purchasing servers and other equipment, you 
    realize that servers cost money.  Does the extra cost justify the 
gain of creating ISOs on the fly?  In my humble opinion, no.  The end 
user can create their own repositories and they can already get the 
source and/or binary files for the individual packages from the site, so 
why do I as the owner of the server need to do anything more?

> Flex my mind here, a lot for a relative newbie (over 1 year old. ;)  ).

Over one year?  I just celebrated my 6th birthday.  Cut my teeth on 
Debian back in early '98.  Now, that was a steep learning curve. 
Fortunately, the Debian install didn't scare me back then.  I was so 
naive I didn't know I was supposed to be scared of it... although it did 
take two days to get it installing and running on that first machine! 
What a long strange trip it's been.  ;-)

-Mike