CODEWITHSUNDEEP
kubernetescontainersk3scontainerd
Doctor
Doctor

Reputation: 7996

Importing images with CTR fails silently

I exported docker images in .tar format.
Then importing those images using K3S and ctr showed no results :

$ sudo k3s ctr i import myimage.tar
$

No output from import cmd ?

$ sudo k3s ctr i ls
$

Nothing there....

Upvotes: 5

Views: 8363

Answers (2)

COvayurt
COvayurt

Reputation: 895

I found out that in my case; I've created an image from image ID, not from tag. So when I want to import my image through ctr, It cannot recognize the tag. So it could not create an image.

Let having a docker image like:

REPOSITORY               TAG        IMAGE ID       CREATED        SIZE
hel.lo/repopath/dev      my-image   5b40ecbbea23   3 hours ago    230MB

So if you save the image with the below command, ctr cannot create an image.

docker save 5b40ecbbea23 > my-image.tar

If you open the created tar file and look at the manifest.json file, you will see something like below(RepoTags is null):

[
  {
    "Config": "5b40ecbbea27ebdfbedabb732e228cb5649b0383ef6508257263978586cc8f9c.json",
    "RepoTags": null,
    "Layers": [...]
  }
]

Once you save the image via below command, it could create an image:

docker save hel.lo/repopath/dev:my-image > my-image.tar

If you open the created tar file and look at the manifest.json file, you will see something like below(RepoTags is hel.lo/repopath/dev:my-image:my-image):

[
  {
    "Config": "5b40ecbbea27ebdfbedabb732e228cb5649b0383ef6508257263978586cc8f9c.json",
    "RepoTags": [
      "hel.lo/repopath/dev:my-image:my-image"
    ],
    "Layers": [...]
  }
]

Upvotes: 5

Doctor
Doctor

Reputation: 7996

Adding --digest=true worked for me :

$ sudo k3s ctr i import myimage.tar --digests=true
unpacking import-2021-05-19@sha256:f9952729292daa8d099c7bc3275f483fdb11ffa9bb1fc394bc06b44c101047e2 (sha256:f9952729292daa8d099c7bc3275f483fdb11ffa9bb1fc394bc06b44c101047e2)...done

And listing images also confirms that the importation has worked :

$ sudo k3s ctr i ls  
...  
import-2021-05-19@sha256:f99527292fa9bb1fc394bc06b44c101047e2 application/vnd.docker.distribution.manifest.v2+json sha256:f9952729292dac06b44c101047e2 939.9 MiB linux/amd64 io.cri-containerd.image=managed

Upvotes: 8

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