[clug] Debian Jessie (Testing, ) "no installable kernel was found in the defined APT sources"

[Scott Ferguson]

Some small additions and clarifications


On 18/10/14 13:34, Tomasz Ciolek wrote:
> All 
> 
> On Sat, Oct 18, 2014 at 10:58:31AM +1100, George at Clug wrote:
>>     Tomasz,
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> What I did, to upgrade my wheezy desktop to jessie, was this:
> 
> 0. I backed up all my data and critical system and application config files to 
> an external HDD. Just in case. 
> 
> 1. Edited /etc/apt/sources.list to be like so: 
> 
> deb http://mirror.internode.on.net/pub/debian/ jessie main contrib non-free
> deb http://mirror.internode.on.net/pub/debian/ jessie-updates main contrib non-free
> deb http://security.debian.org/ jessie/updates main contrib non-free

Alternatively use the redirector to automagically select the local mirror:-
http://http.debian.net/

Demo:-
http://http.debian.net/demo.html

See also:-
https://wiki.debian.org/DebianGeoMirror

You can also use netselect-apt to choose the fastest reposititory. e.g.
(as root:-
cp /etc/apt/sources.list{,.bak}
netselect-apt testing

If you run more than one Debian box I'd recommend installing
apt-cacher-ng on one box and routing (use /etc/apt/apt.conf.d/90proxy)
all apt requests through it to avoid downloading the same packages twice
on the same network. Yes, apt-cacher-ng will cope with non-official
debian repostitories, *and* other distros, and mixed debian repositories
(old-stable, stable, testing, unstable, experimental)

You can also do this manually - when you do apt-get
upgrade/dist-upgrade/install the packages are downloaded to
/var/cache/apt/archives (until you run apt-get clean/autoclean). Apt
will look in the cache before downloading - so if update/install to one
box you can simply copy those to another machine and avoid duplicate
downloads. e.g.:-
scp /var/cache/apt/archives/*.deb root at somebox:/var/cache/apt/archives
(presuming you have previously used ssh-copy-id to authenticate the user
as root at somebox)

> 
> Note: Internode is my ISP, so choose a repository close to you. Debian have a list of 
> available mirrors, but make sure your browse the chosen mirror and find out what URL
> leads to the root debian directory, as URL paths differ between mirrors. 

The Debian mirrors page lists all official mirrors, but, there are
others. It's worthwhile checking if your ISP has a mirror, often they do
and downloads from those mirrors (sometimes) don't count against your
broadband limits. Otherwise some locals 'may' find the local uber mirror
faster:-
http://debian.mirror.uber.com.au/debian/

> 
> 2. as root (or with sudo) I run 'apt-get update' to pull data from repositories
> 
> 3. as root (or with sudo) I run 'apt-get dist-upgrade' to upgrade the distribution installation.
> Much download and installing will happen. 

That should be "apt-get upgrade" - not "dist-upgrade"
e.g. (as root)
apt-get update && apt-get upgrade

If, while doing an upgrade you get a message about "packages being held
back" it means that some *core* packages have changed. In which case you
will need to use "dist-upgrade" - *after* the upgrade.
Dist-upgrades will usually result in orphan packages.

> 
> 4. as root as root (or with sudo) I run 'apt-get --purge autoremove' to remove obsolete
> and unnecessary packages and purge their configuration files

Only necessary if during "apt-get upgrade" apt notifies of orphaned
packages.

Tip - install deborphan to find other orphan packages.
deborphan # display orphan packages

To remove them (as root):-
apt-get -y --purge remove `deborphan`  # remove and purge configuration
files for orphan packages.

debfoster will do more, but is a little more complicated.

> 
> 
> Caveats and disclaimers: 
> 
> 0. There is no easy downgrade path. Reinstall is the safest way to do that.
> 
> 1. jessie is NOT a stable distribution. It pulls packages from Sid (unstable) after some 
> period of time, if there is no major bugs logged against the packages. So, sometimes 
> things break. Until the package freeze process begins in November/December this will
> still be the case.

Jessie is Testing. It doesn't "pull"[*1] packages from Sid (Unstable).
Capability additions are frozen in Sid, they then "migrate" to Jessie,
(after sufficient cross-package testing Testing becomes Stable).

Agreed that Jessie is not stable (or Stable) - in that it requires
constant updates, not that it will crash or has frequent glitches.
Unless you have a compelling reason to run Testing (you are a tester, or
cannot get it's features elsewhere) then you are generally better using
stable, and adding backports as a repository. If you simply want the
latest Iceweasel add backports and the Iceweasel backports repository.
If you want stable and features of Testing or Unstable - add those
repositories and use pinning to avoid breaking stable while selectively
installing packages from Testing/Unstable. YMWV.

a useful reference is https://wiki.debian.org/DebianTesting

[*1] that happens if you add mix repostitories in /etc/apt/sources.list
and/or /etc/apt/sources.list.d/*.list - if you choose to do that you
should use pinning (/etc/apt/preferences or preferably
/etc/apt/preferences.d/*.pref) to prevent breakages.

NOTES: I'd recommend using the simulate switch (-s) before running
remove, autoremove, deborphan, upgrade, or (when *core* packages change)
dist-upgrade. If the results look sane, then proceed with the command
minus the -s.  e.g.:-
apt-get -s install $package/s | more # check than nothing important is
going to be removed (it happens), then, if it looks OK:-
apt-get install $package

*Running anything later than old-stable or stable on a server is
generally consider "shoot-foot" :)

*Important*: if you want security, Jessie is not a great choice
https://www.debian.org/security/faq#testing


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HTH

Kind regards