[PATCH 0/2] deb to snap: use the kernel version from the

[Paolo Pisati]

It was pointed to us that using the version from the linux-image-$BRANCH (e.g.
linux-image-generic) package is not a good idea, since that version doesn't map
1:1 to the real kernel that comes from the linux-image-$VER-$ABI-$BRANCH (e.g.
linux-image-4.4.0-98-generic) package - in other words, the same linux meta
package could actually end up using two completely different kernels since it
doesn't keep track of the upload number, and as such we won't be able to tell
univocally which kernel image ended up in the produced kernel snap: to fix this,
i added a mechanism that, given the meta package, it recurse down to find the
real linux kernel package, extract its version and compares it against the
expected version (while previously we used the "apt-get install
$(KERNEL)=$(VERSION)" to force the installation of exactly that linux meta
version, something we can't do anymore now as explained above).

Patch 0001 is a prerequisite for patch 2, and improve over our apt-pinning
method to let us use only kernel packages from the proposed pocket, and remove
the "apt-get install $(KERNEL)=$(VERSION)" mechanism - now we'll just install
the latest version of the required package available.
Patch 0002 is where the real version extraction and checking happens, and it
does so by making the checkversion shell snippet a prerequisite of the install
rule.

I tested the above by rebuilding all our kernel snaps on LP:

pc-kernel - i386 and amd64
raspi2-kernel - armhf
snapdragon-kernel - arm64
gke, gcp and aws - amd64

and testing all the possible error paths or conditions.

Since these patches don't change anything in the content on the generated kernel
snap (actually they add a stricter version checking and a better pinning), the
risk of regression is very low.

This series of patches apply to our 'deb to snap' packaging scripts located
here:
    
git://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux-snap/+git/xenial

and should be applied to the master Makefile, while all the topic
branches should get the version field (version: in snapcraft.yaml) changed to
point to the version from the linux-image-$VER-$ABI-$BRANCH corresponding
package.

In other words, and at the time of this writing, these are the version that
should be used for all the topic branches:

pc-kernel: 4.4.0-98.121 (linux-image-4.4.0-98-generic / linux-signed-image-4.4.0-98-generic)
raspi2-kernel: 4.4.0-1076.84 (linux-image-4.4.0-1076-raspi2)
snapdragon-kernel: 4.4.0-1078.83 (linux-image-4.4.0-1078-snapdragon)
aws-kernel: 4.4.0-1039.48 (linux-image-4.4.0-1039-aws)
gcp-kernel: 4.10.0-1008.8 (linux-image-4.10.0-1008-gcp)
gke-kernel: 4.4.0-1033.33 (linux-image-4.4.0-1033-gke)

I could have sent a separate version patch for every branch, but since it takes
some time to get stuff reviewed and applied, and you might want to use the kernel
available in -proposed instead of the one in -security/updates, i'll leave the
version extraction to you.

Paolo Pisati (2):
  deb to snap: better apt-pinning, use $RELEASE everywhere and
    explicitly exclude linux-firmware from -proposed
  deb to snap: recurse down to find the real kernel image package, and
    chek its version

 Makefile | 42 +++++++++++++++++++++++++++++-------------
 1 file changed, 29 insertions(+), 13 deletions(-)

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