RFC: podman prune images by default should only delete dangling images

[dustymabe]

/kind bug

Description

possibly a variant of #1154. podman image prune seems to remove all images, not just unnamed images.

[vagrant@vanilla-f29-atomic-testing foo]$ echo "foo" > file
[vagrant@vanilla-f29-atomic-testing foo]$ 
[vagrant@vanilla-f29-atomic-testing foo]$ cat Dockerfile 
FROM registry.fedoraproject.org/fedora:29
COPY file /file
[vagrant@vanilla-f29-atomic-testing foo]$ sudo podman build -t foo .
STEP 1: FROM registry.fedoraproject.org/fedora:29
STEP 2: COPY file /file
--> 30dac0f34c014ff719aec51c05423f6dec000785a912e312c1fe4d3d36a31d04
STEP 3: COMMIT foo
--> 4b9cdb6bdd985c60619342c3b2eccf51bf000454ff73133d6fd0989d3994e5b1
[vagrant@vanilla-f29-atomic-testing foo]$ 
[vagrant@vanilla-f29-atomic-testing foo]$ sudo podman images
REPOSITORY                          TAG      IMAGE ID       CREATED         SIZE
localhost/foo                       latest   4b9cdb6bdd98   9 seconds ago   283 MB
<none>                              <none>   30dac0f34c01   9 seconds ago   283 MB
registry.fedoraproject.org/fedora   29       69c5db8b64a7   11 days ago     283 MB
registry.fedoraproject.org/fedora   28       ded494ce3076   3 months ago    264 MB
[vagrant@vanilla-f29-atomic-testing foo]$ 
[vagrant@vanilla-f29-atomic-testing foo]$ sudo podman image prune
69c5db8b64a76b5f0b3ac812f317f828d3d4d8e7b399ea196de6de659c225b96
ded494ce3076e8f2d264235fdb09da5970921d8317f8fd024ab65821bf13e29f
30dac0f34c014ff719aec51c05423f6dec000785a912e312c1fe4d3d36a31d04
4b9cdb6bdd985c60619342c3b2eccf51bf000454ff73133d6fd0989d3994e5b1
[vagrant@vanilla-f29-atomic-testing foo]$ 
[vagrant@vanilla-f29-atomic-testing foo]$ sudo podman images
[vagrant@vanilla-f29-atomic-testing foo]$ 

podman version/info

[vagrant@vanilla-f29-atomic-testing foo]$ rpm -q podman
podman-1.0.0-1.git82e8011.fc29.x86_64
[vagrant@vanilla-f29-atomic-testing foo]$
[vagrant@vanilla-f29-atomic-testing foo]$ sudo podman version
Version:       1.0.0
Go Version:    go1.11.4
Git Commit:    "49780a1cf10d572edc4e1ea3b8a8429ce391d47d"
Built:         Mon Jan 14 20:38:17 2019
OS/Arch:       linux/amd64
[vagrant@vanilla-f29-atomic-testing foo]$ sudo podman info 
host:
  BuildahVersion: 1.6-dev
  Conmon:
    package: podman-1.0.0-1.git82e8011.fc29.x86_64
    path: /usr/libexec/podman/conmon
    version: 'conmon version 1.12.0-dev, commit: 49780a1cf10d572edc4e1ea3b8a8429ce391d47d'
  Distribution:
    distribution: fedora
    version: "29"
  MemFree: 3407650816
  MemTotal: 4133462016
  OCIRuntime:
    package: runc-1.0.0-67.dev.git12f6a99.fc29.x86_64
    path: /usr/bin/runc
    version: |-
      runc version 1.0.0-rc6+dev
      commit: d164d9b08bf7fc96a931403507dd16bced11b865
      spec: 1.0.1-dev
  SwapFree: 0
  SwapTotal: 0
  arch: amd64
  cpus: 4
  hostname: vanilla-f29-atomic-testing
  kernel: 4.20.3-200.fc29.x86_64
  os: linux
  rootless: false
  uptime: 1h 7m 23.14s (Approximately 0.04 days)
insecure registries:
  registries: []
registries:
  registries:
  - docker.io
  - registry.fedoraproject.org
  - quay.io
  - registry.access.redhat.com
  - registry.centos.org
store:
  ConfigFile: /etc/containers/storage.conf
  ContainerStore:
    number: 0
  GraphDriverName: overlay
  GraphOptions: null
  GraphRoot: /var/lib/containers/storage
  GraphStatus:
    Backing Filesystem: xfs
    Native Overlay Diff: "true"
    Supports d_type: "true"
  ImageStore:
    number: 0
  RunRoot: /var/run/containers/storage

[rhatdan]

@baude Could you look at this?

[mheon]

I think this might be intended behavior? podman image prune says it removes all images not being used by containers.

Maybe this should be gated by a flag, separate from "remove leftover intermediate images"?

[dustymabe]

I think this might be intended behavior? podman image prune says it removes all images not being used by containers.

That is not my interpretation of the help text:

[dustymabe@hattop ~]$ podman image prune --help
NAME:
   podman image prune - Remove unused images

USAGE:
   podman image prune [arguments...]

DESCRIPTION:
   
  podman image prune

  Removes all unnamed images from local storage

To me Removes all unnamed images from local storage would only touch images that don't have a label.

[TomSweeneyRedHat]

FWIW, my thinking was prune should be removing any images with a tag and leaving the rest alone.

[TomSweeneyRedHat]

Ugh, love md4 sometimes in GitHub. "images with a tag" s/b "images with a <none><none> tag"

[baude]

Nope, to be compatible with docker, prune removes all unused images (images that are not being used by a container). the atomic cli prune command was just the none images. the help text is incorrect and should be updated. you can see in the short description, it says unused.

[dustymabe]

atomic cli prune command was just the none images

how do we get that functionality ^^ - that's what I'm interested in

[baude]

what do you want the command line switch to be? it should probably be somethign like --only-something-or-another

[TomSweeneyRedHat]

Hmmm,

I'm looking at: https://docs.docker.com/engine/reference/commandline/image_prune/

and it says:

Extended description

Remove all dangling images. If -a is specified, will also remove all images not referenced by any container.

Where danglng errors have the <none> tag. Where did you find your prune info or am I misreading this doc?

[baude]

fine thats seems to be what we should do.