nerdctl build --namespace k8s.io versus Dockerfile FROM

[starpit]

Hello!

I am trying to get nerdctl to build into rancher-desktop/k8d's k8s.io namespace directly. This is generally working... until I try to build a Dockerfile that has a FROM that points to an image that is in that namespace. At this point, nerdctl seems to ignore the --namespace argument I gave it, and instead query the registry directly.

Note: This is probably unrelated to any particular --namespace argument. The main question is: docker build seems to understand that it can query the local cache/registry first. Does nerdctl build support this?

FROM ghcr.io/myorg/mypackage:mytag

$ nerdctl build --namespace=k8s.io .
Dockerfile:1
--------------------
   1 | >>> FROM ghcr.io/myorg/mypackage:mytag
--------------------
error: failed to solve: ghcr.io/myorg/mypackage:mytag: ghcr.io/myorg/mypackage:mytag: not found

I have verified that the ghcr.io/myorg/mypackage:mytag package exists in the k8s.io namespace:

$ nerdctl --namespace=k8s.io images | grep -q ghcr.io/myorg/mypackage:mytag && echo yup || echo nope
yup

thanks!
@starpit

[starpit]

Hmm.. I see this: #2550

So it looks like, for now, I need to build in two passes: first to --namespace=buildkit, and then to --namespace=k8s.io.