Don't run the extraction tar container for podman

[afbjorklund]

The preloaded images will be extracted anyway, using ssh.

But if creating them on the volume before the container is
booted, means that /var will not be fully copied over to it.
And without /var/lib/dpkg and others, kicbase will not boot.
So skip the parallel extraction for podman, do it afterwards.

Probably shouldn't mount all of /var, but just a sub-set...

Closes #8056

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[codecov-io]

Codecov Report

Merging #8057 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #8057   +/-   ##
=======================================
  Coverage   35.45%   35.45%           
=======================================
  Files         146      146           
  Lines        9284     9284           
=======================================
  Hits         3292     3292           
  Misses       5592     5592           
  Partials      400      400           

[medyagh]

Makes sense, I believe for podman the volume is just a folder on your system. If the host system had lz4 installed we could do it with lz4 in parallel. But probably that would be too much depending on user tools.

[medyagh]

/ok-to-test

[minikube-pr-bot]

kvm2 Driver
docker Driver

[afbjorklund]

Makes sense, I believe for podman the volume is just a folder on your system. If the host system had lz4 installed we could do it with lz4 in parallel. But probably that would be too much depending on user tools.

You could always go back to gzip, or even to plain .tar if that was the only problem. Or perhaps bundle lz4 with minikube, like we did for lzma when it was new and xz hadn't taken over yet.

[afbjorklund]

Makes sense, I believe for podman the volume is just a folder on your system.

It's a folder on Docker too, the main difference is in timing when it copies the files over.

But otherwise it is quite similar, there are only small differences in paths and timestamps:

 docker volume inspect docker
[
    {
        "CreatedAt": "2020-05-09T14:36:50+02:00",
        "Driver": "local",
        "Labels": {
            "created_by.minikube.sigs.k8s.io": "true",
            "name.minikube.sigs.k8s.io": "docker"
        },
        "Mountpoint": "/var/lib/docker/volumes/docker/_data",
        "Name": "docker",
        "Options": {},
        "Scope": "local"
    }
]
 sudo podman volume inspect podman
[
     {
          "Name": "podman",
          "Driver": "local",
          "Mountpoint": "/var/lib/containers/storage/volumes/podman/_data",
          "CreatedAt": "2020-05-09T14:35:14.431826651+02:00",
          "Labels": {
               "created_by.minikube.sigs.k8s.io": "true",
               "name.minikube.sigs.k8s.io": "podman"
          },
          "Scope": "local",
          "Options": {
               
          }
     }
]

So we have 5M of various junk under /var in the ubuntu image.
And that gets copied, from the image storage to the volume storage...

 docker run -it ubuntu:19.10 sh -c "du -hxcs /var/*"
4.0K	/var/backups
1.5M	/var/cache
3.7M	/var/lib
4.0K	/var/local
0	/var/lock
252K	/var/log
4.0K	/var/mail
4.0K	/var/opt
0	/var/run
4.0K	/var/spool
4.0K	/var/tmp
5.4M	total
 sudo ls /var/lib/docker/volumes/docker/_data
backups  cache	lib  local  lock  log  mail  opt  run  spool  tmp
 sudo ls /var/lib/containers/storage/volumes/podman/_data
backups  cache	lib  local  lock  log  mail  opt  run  spool  tmp

But we only actually use a couple of those, like #8056 (comment)

The rest just gets duplicated (from the image), for no particular reason.

[afbjorklund]

My solution going forward would be to maybe keep the /var volume (for compatibiity when upgrading), but to only mount a subset of the existing folders. Like we are doing with the ISO, to make them same.

But will open a new issue for that.

I don't think the storage-provisioner works in KIC either, since we are missing those mounts.
And it will be weird to have them under "var", so better move it (var) to a volume subdirectory.

Another issue (storage-provisoner)