Add support for Dockerfile using a variable within their FROM line, today it fails due to usage of docker inspect not handling the ARG

[hpe-ykoehler]

I have a Dockerfile that needs to use an ARG in the FROM line:

https://docs.docker.com/engine/reference/builder/#understand-how-arg-and-from-interact

ARG VERSION=latest
FROM busybox:$VERSION
ARG VERSION

This works with docker build but fails with devcontainer because devcontainers try to build the FROM image name without honoring the ARG and call docker inspect which then return a failure.

[126 ms] @devcontainers/cli 0.52.1. Node.js v18.18.2. linux 5.15.0-86-generic x64.
{"outcome":"error","message":"Command failed: docker inspect --type image busybox:VERSION","description":"An error occurred building the container."}

[samruddhikhandale]

Hi 👋

We have dev container images use the same ARG pattern (example), and we have not seen any issues with devcontainer build, devcontainer up and devcontainer exec commands.

@hpe-ykoehler Is there a specific command which fails for you? Also, can you try replacing FROM busybox:$VERSION with 👇 , I wonder if that's the issue. Thanks!

FROM busybox:${VERSION}

[hpe-ykoehler]

I did use both form with the same result, the "docker inspect" line is not apparently taking those into account.

I am unclear how the docker inspect would actually be able to solve those since I see no argument being passed to the docker inspect command line.

Have you try using a different value than the default with the example provided above?

[samruddhikhandale]

Hmm, this is strange. I tried it within a codespace and locally on a Mac machine (even after changing the default ARG value), it works for me 😅 In my case, and from the logs, I can see that the docker inspect command has the value already substituted from ARG

Okay, now I tried with your example provided in the issue (ie busybox). Even, that worked for me, but I can see that it jumped thorough different auth mechanisms before being able to inspect that image. I wonder if that's the issue in your case.

@hpe-ykoehler Can you run the devcontainer command by adding --log-level trace and paste the logs? Thanks!

[hpe-ykoehler]

Ok let me try on my machine with this example and try to understand what the difference in my case is.