nim-1.x images actually offer nim-2.2.6

[GreyCat]

Starting circa ~2 weeks ago (mid-late January 2026), something got broken in nim-1.6.20 images, and instead of nim-1.6.20 in it (which is expected), we've started seeing nim-2.2.6:

$ podman run -it nimlang/nim:1.6.20-alpine
Trying to pull docker.io/nimlang/nim:1.6.20-alpine...
Getting image source signatures
Copying blob 7b6a8cbc8eed done   | 
Copying blob 76eb174b37c3 done   | 
Copying blob 0f2032231390 done   | 
Copying config 32c97bf04c done   | 
Writing manifest to image destination
Nim Compiler Version 2.2.6 [Linux: amd64]
Compiled at 2025-10-31
Copyright (c) 2006-2025 by Andreas Rumpf

git hash: ab00c56904e3126ad826bb520d243513a139436a
active boot switches: -d:release -d:danger

The same goes with nim-1.6.20-slim. I've also checked nimlang/nim:1.6.6-slim, same story:

> podman run -it nimlang/nim:1.6.6-slim
Trying to pull docker.io/nimlang/nim:1.6.6-slim...
Getting image source signatures
Copying blob 6f5b01abc24d done   | 
Copying blob a3629ac5b9f4 skipped: already exists  
Copying blob b1b2f3e3e9d0 done   | 
Copying config ca48e2bd93 done   | 
Writing manifest to image destination
Nim Compiler Version 2.2.6 [Linux: amd64]
Compiled at 2025-10-31
Copyright (c) 2006-2025 by Andreas Rumpf

git hash: ab00c56904e3126ad826bb520d243513a139436a
active boot switches: -d:release -d:danger

[moigagoo]

@GreyCat please try I it again. I've completely revamped the image generation routine and republished the images.

[GreyCat]

@moigagoo Still getting same error, unfortunately — the image still seems to pack 2.2.6 instead of 1.6.20:

https://github.com/kaitai-io/kaitai_struct_docker_images/actions/runs/22011462709/job/65698741437#step:4:143

> [7/7] RUN ./validate '^Nim Compiler Version 1\.6\.20 ':
0.134 Nim version:
0.134 ---
0.134 Nim Compiler Version 2.2.6 [Linux: amd64]
0.134 Compiled at 2025-10-31
0.134 Copyright (c) 2006-2025 by Andreas Rumpf
0.134 
0.134 git hash: ab00c56904e3126ad826bb520d243513a139436a
0.134 active boot switches: -d:release -d:danger
0.134 ---
0.136 Wrong Nim version detected!

[generalmimon]

I tested all tags from https://hub.docker.com/r/nimlang/nim/tags?name=1.6.20 and found that nimlang/nim:1.6.20 was updated 2026-03-04T08:52:24Z ("4 hours ago") and provides the correct version, but 1.6.20-slim and 1.6.20-alpine were not (they were last updated 2026-02-01T05:58:24Z and 2026-01-31T00:44:44Z respectively, i.e. "4 weeks ago").

There are also old 1.6.20-{alpine,ubuntu}-{slim,regular} tags from 2025-08-01 ("7 months ago") and 1.6.20-{ubuntu,regular} from 2025-04-11 ("10 months ago"), which also provide the right version, but they are apparently not maintained anymore, so I'm mentioning them only for completeness (it's clear that they should no longer be used):

$ podman images --digests nim
REPOSITORY             TAG                    DIGEST                                                                   IMAGE ID      CREATED        SIZE
docker.io/nimlang/nim  1.6.20                 sha256:65b0fcc4b98bfc5cae6e68bc011f3255e95270f25c738038c1f0dd26ef02f984  6660d4c7f91c  4 hours ago    581 MB
docker.io/nimlang/nim  1.6.20-slim            sha256:06dd0a423da57af092eb5ac9aab7554f224aa790f609d6a767b082877ccdf16f  fea7fbdc07ae  4 weeks ago    376 MB
docker.io/nimlang/nim  1.6.20-alpine          sha256:8c2e502e425fbf9b84ff7b7f73cbb826d83640018cb7927748dad8caa2429891  32c97bf04cd7  4 weeks ago    569 MB
docker.io/nimlang/nim  1.6.20-alpine-slim     sha256:c5b8b51155cfa8235b90fd601ee76a8bbeb177edc2886ad030f107fd6f3239b4  2a53a39d8e0b  7 months ago   299 MB
docker.io/nimlang/nim  1.6.20-alpine-regular  sha256:c9870026fa1f7482a4fd5b931c9861b3945fa3ba5d4b5693bdd657be9d7cd9f3  f8d309883708  7 months ago   493 MB
docker.io/nimlang/nim  1.6.20-ubuntu-slim     sha256:49f3d300e69a6081ea4dc71b075db7b9bdc1f773e4240758f06493d0de9097cb  fe7d215ad737  7 months ago   521 MB
docker.io/nimlang/nim  1.6.20-ubuntu-regular  sha256:4a2b2cce6670fc6251632e2fdf90445d322901b019defcb965311e5505e1655b  fd04efba31a2  7 months ago   802 MB
docker.io/nimlang/nim  1.6.20-ubuntu          sha256:95305b8ff463aedc40dc062d6cc4f5269be96c24d0164cd0a375972e84106aa6  a5518893e84b  10 months ago  764 MB
docker.io/nimlang/nim  1.6.20-regular         sha256:95305b8ff463aedc40dc062d6cc4f5269be96c24d0164cd0a375972e84106aa6  a5518893e84b  10 months ago  764 MB

$ podman run --rm docker.io/nimlang/nim:1.6.20 nim --version | grep -F 'Nim Compiler Version '
Nim Compiler Version 1.6.20 [Linux: amd64]

$ podman run --rm docker.io/nimlang/nim:1.6.20-slim nim --version | grep -F 'Nim Compiler Version '
Nim Compiler Version 2.2.6 [Linux: amd64]

$ podman run --rm docker.io/nimlang/nim:1.6.20-alpine nim --version | grep -F 'Nim Compiler Version '
Nim Compiler Version 2.2.6 [Linux: amd64]

$ podman run --rm docker.io/nimlang/nim:1.6.20-alpine-slim nim --version | grep -F 'Nim Compiler Version '
Nim Compiler Version 1.6.20 [Linux: amd64]

$ podman run --rm docker.io/nimlang/nim:1.6.20-alpine-regular nim --version | grep -F 'Nim Compiler Version '
Nim Compiler Version 1.6.20 [Linux: amd64]

$ podman run --rm docker.io/nimlang/nim:1.6.20-ubuntu-slim nim --version | grep -F 'Nim Compiler Version '
Nim Compiler Version 1.6.20 [Linux: amd64]

$ podman run --rm docker.io/nimlang/nim:1.6.20-ubuntu-regular nim --version | grep -F 'Nim Compiler Version '
Nim Compiler Version 1.6.20 [Linux: amd64]

$ podman run --rm docker.io/nimlang/nim:1.6.20-ubuntu nim --version | grep -F 'Nim Compiler Version '
Nim Compiler Version 1.6.20 [Linux: amd64]

$ podman run --rm docker.io/nimlang/nim:1.6.20-regular nim --version | grep -F 'Nim Compiler Version '
Nim Compiler Version 1.6.20 [Linux: amd64]

[generalmimon]

I would say that this analysis I did in #78 (comment) reveals a deeper problem: as users, we have no easy way of finding out which tag flavors are still being updated and which have been discontinued. It would make sense for such a policy to be documented in the README, but unfortunately it's not - it only explains the latest tag and unflavored version tags:

docker-images/README.md

Lines 39 to 47 in 282c2d8

	## Understanding the Tags
	We use a "floating" tag strategy based on Semantic Versioning. This allows you to choose between absolute pinning or automatic updates for patches and minor versions.
	- `latest`: Points to the most recent stable release.
	- `2`: Points to the latest stable release in the 2.x.x series.
	- `2.2`: Points to the latest stable release in the 2.2.x series.
	- `2.2.8`: An immutable tag for a specific version.

For example, if I search for all the tags associated with the latest Nim version 2.2.8 (https://hub.docker.com/r/nimlang/nim/tags?name=2.2.8), I see that there are only two - the unflavored tag 2.2.8 and the -slim variant 2.2.8-slim, both pushed 3 days ago:

$ podman images --digests nim
REPOSITORY             TAG                    DIGEST                                                                   IMAGE ID      CREATED        SIZE
(...)
docker.io/nimlang/nim  2.2.8                  sha256:29c9b43568bb09e2a0cd6b8d108a4e0374038a79715e9ed216b466952ed526f4  f986f48eb6d3  3 days ago     798 MB
docker.io/nimlang/nim  2.2.8-slim             sha256:f13047b8a1015fd29c0faae2c84131fc8881b988e2c5719e1eb6ec2603b5f9e9  0f8557731aab  3 days ago     373 MB
(...)

Does that mean that -slim is the only flavor that is still maintained, and any other flavors that were previously provided, for example -alpine, are no longer maintained? I'm not so sure, because according to https://hub.docker.com/r/nimlang/nim/tags?name=alpine, two -alpine tags were updated just 3 days ago (2026-03-01), namely 2.2.0-alpine and 2.2.2-alpine:

$ podman images --digests nim
REPOSITORY             TAG                    DIGEST                                                                   IMAGE ID      CREATED        SIZE
(...)
docker.io/nimlang/nim  2.2.0-alpine           sha256:15168851b7694ddcb4c62d978c72cc72a6f59835c82fdd89bb1cb457623ec5b6  8c4d53bf3948  3 days ago     569 MB
docker.io/nimlang/nim  2.2.2-alpine           sha256:bda1ee5a28f27ef987dc50203b065c1a11180580f6ebcef8e215c4d916e7464b  3754d2d71100  3 days ago     569 MB
(...)

2.2.0 and 2.2.2 are not even the latest Nim 2.2 versions, that would be Nim 2.2.8. These two recent updates to -alpine tags are therefore very confusing to me.

To sum up, it would be great to have a clear policy documented in the README specifying which tag variants are supported. Of course, it is then essential to stick to it (i.e. maintain the automation of pushing Docker images in such a way that this policy is followed).

[moigagoo]

@generalmimon I'm 100% with you on the poor documentation issue. The root of this problem is that I'm actively rewriting the images to comply with the official Docker Hub guidelines and unfortunately there's no other way to test them than build and push to prod.

Also, I had to lose some flavors during these updates, namely alpine-based images and slim images. Alpine images had to be removed to simplify maintenance and slim images are just not what Docker Hub normally means by slim.

I should probably finalize the changes, remove the unsupported images from Docker Hub, and update the docs. I'll do that ASAP but it doesn't depend only on me—there's a PR to the official Docker Hub images repo under review and I'm making changes to pass review all the time.

I'm sorry about the inconvenience and confusion. Hopefully, I'll be able to fix those issues shortly.

[generalmimon]

@moigagoo:

The root of this problem is that I'm actively rewriting the images to comply with the official Docker Hub guidelines

there's a PR to the official Docker Hub images repo under review and I'm making changes to pass review all the time.

Sounds awesome, thank you for this effort! I hope it will be merged soon.

Also, I had to lose some flavors during these updates, namely alpine-based images and slim images. Alpine images had to be removed to simplify maintenance and slim images are just not what Docker Hub normally means by slim.

Makes sense, thanks for the explanation. I've just found docker-library/official-images#19453, where I can also read the relevant context. I'll follow this PR in case something changes, but for the time being, this answers my immediate question: neither alpine nor slim images will be supported in the future. Therefore, on our side in kaitai-io/kaitai_struct_docker_images#2, we'll probably just switch to regular images and call it a day.

I should probably finalize the changes, remove the unsupported images from Docker Hub, and update the docs.

Actually, I don't think it's a good idea to delete published tags. This will likely cause disruption to other users of the nimlang/nim Docker image when they least expect it, and they won't be happy about it.

I think a better strategy is to simply stop publishing any tags other than the only supported (unflavored) one for all future versions of Nim. This ensures that whatever people are using now will continue to work. Only when they decide to update will they have to deal with the fact that -alpine and -slim images no longer exist for the latest versions.

---

Anyway, I believe this issue can be closed because nimlang/nim:1.6.20 is the only supported Nim 1.6.20 tag and it provides Nim 1.6.20 as it should (as I showed in #78 (comment)).

[generalmimon]

#78 (comment):

Anyway, I believe this issue can be closed because nimlang/nim:1.6.20 is the only supported Nim 1.6.20 tag and it provides Nim 1.6.20 as it should (as I showed in #78 (comment)).

Hmm, although the Nim 1.x images seem to be fine (at least based on this anecdotal evidence - I don't want to check them all):

$ podman run --rm docker.io/nimlang/nim:1.6.20 nim --version | grep -F 'Nim Compiler Version '
Nim Compiler Version 1.6.20 [Linux: amd64]

$ podman run --rm docker.io/nimlang/nim:1.6.18 nim --version | grep -F 'Nim Compiler Version '
Nim Compiler Version 1.6.18 [Linux: amd64]

$ podman run --rm docker.io/nimlang/nim:1.6.6 nim --version | grep -F 'Nim Compiler Version '
Nim Compiler Version 1.6.6 [Linux: amd64]

$ podman images --digests nim
REPOSITORY             TAG                    DIGEST                                                                   IMAGE ID      CREATED        SIZE
docker.io/nimlang/nim  1.6.20                 sha256:65b0fcc4b98bfc5cae6e68bc011f3255e95270f25c738038c1f0dd26ef02f984  6660d4c7f91c  9 hours ago    581 MB
docker.io/nimlang/nim  1.6.18                 sha256:75615327493cd199e71ce5cf7af85eb1010427e00029049d0849598811b1243c  dce869e8289f  9 hours ago    581 MB
docker.io/nimlang/nim  1.6.6                  sha256:f172f08ccb433b901dcbba2b8f9a95ba3c0f907e85210ae0e8320b6c0f54f368  968e9bbd8d7c  9 hours ago    580 MB
(...)

... the Nim 2.2.x images still need attention, because nimlang/nim:2.2.6 provides Nim 2.2.8:

$ podman run --rm docker.io/nimlang/nim:2.2.6 nim --version | grep -F 'Nim Compiler Version '
Nim Compiler Version 2.2.8 [Linux: amd64]

$ podman images --digests nim
REPOSITORY             TAG                    DIGEST                                                                   IMAGE ID      CREATED        SIZE
(...)
docker.io/nimlang/nim  2.2.8                  sha256:29c9b43568bb09e2a0cd6b8d108a4e0374038a79715e9ed216b466952ed526f4  f986f48eb6d3  3 days ago     798 MB
docker.io/nimlang/nim  2.2.6                  sha256:f4747197072cd658cb0b31d7c9826be78884cf23ee27f98934611b6b7a309506  082f95b695fb  3 days ago     798 MB

[moigagoo]

@generalmimon seems to be fixed with the latest rebuild:

 docker run --rm nimlang/nim:2.2.6 nim --version
Unable to find image 'nimlang/nim:2.2.6' locally
2.2.6: Pulling from nimlang/nim
01d7766a2e4a: Pull complete
65a4a64762a6: Pull complete
4f4fb700ef54: Pull complete
36a6ec4b26e7: Pull complete
5e444fb64eca: Pull complete
Digest: sha256:27eab07ecd9fa0a2ef0a1ecc9573150ef91171899769336461f1afc909b3375c
Status: Downloaded newer image for nimlang/nim:2.2.6
Nim Compiler Version 2.2.6 [Linux: amd64]
Compiled at 2025-10-31
Copyright (c) 2006-2025 by Andreas Rumpf

git hash: ab00c56904e3126ad826bb520d243513a139436a
active boot switches: -d:release

[generalmimon]

@moigagoo Nice! Then I believe this issue can be closed, as I'm not aware of any supported tag that would provide a different version than the one advertised.