Kernel with CONFIG_IKHEADERS for BPF tools on Kubernetes

[alban]

BCC tools need to have access to kernel headers. It can be done either
by installing linux-headers packages or by having a kernel compiled with
CONFIG_IKHEADERS so that enough information can be retrieved via
/sys/kernel/kheaders.tar.xz.

BCC tools are used in Inspektor Gadget, a collection of tools for
developers of Kubernetes applications. I would like Inspektor Gadget to
support Minikube.

Fixes #8556

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[k8s-ci-robot]

Hi @alban. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[minikube-bot]

Can one of the admins verify this patch?

[alban]

It seems to work:

$ ./out/minikube start --iso-url=file://$(pwd)/out/minikube.iso
$ ./out/minikube ssh
                         _             _            
            _         _ ( )           ( )           
  ___ ___  (_)  ___  (_)| |/')  _   _ | |_      __  
/' _ ` _ `\| |/' _ `\| || , <  ( ) ( )| '_`\  /'__`\
| ( ) ( ) || || ( ) || || |\`\ | (_) || |_) )(  ___/
(_) (_) (_)(_)(_) (_)(_)(_) (_)`\___/'(_,__/'`\____)

$ uname -a
Linux minikube 5.4.40 #1 SMP Sat Jun 27 15:36:59 UTC 2020 x86_64 GNU/Linux
$ ls -l /sys/kernel/kheaders.tar.xz
-r--r--r-- 1 root root 3438056 Jun 27 16:33 /sys/kernel/kheaders.tar.xz
$ 

[alban]

/assign @josedonizetti

[afbjorklund]

@alban : we don't have any packages on the minikube iso, so this could be a good alternative

3 MB doesn't seem to much to pay (size addition to the iso), for having better BPF compatibility

[rata]

/ok-to-test

[minikube-pr-bot]

kvm2 Driver
docker Driver

[alban]

Thanks for the quick review @afbjorklund! I understand we need a /lgtm for a lgtm label (in addition to the github review). Could you lgtm or approve the PR?

[afbjorklund]

Actually we need a merge and then a new ISO, and we are currently having some issues with it...

[afbjorklund]

But I think the configuration change looks good, maybe we need to update the docs as well ?

[afbjorklund]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: afbjorklund, alban

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