Alllow features to copy from another images (infer devcontainer dockerfiel)

[ThePlenkov]

Hi!

Let's assume we have a feature Z which installs Z command with a script.

Let's assume this script takes few minutes to update dependencies and install/build the package.

If we use feature + we develop something in a remote container, rebuilding the container would require us to wait for this feature to be installed again and again.

At same time let's say there is already another container where Z is already installed and avilable as compiled executable file.

So copying this file from prebuilt container would be enough.

So what I do now in my docker file:

FROM z_image as z
FROM devcontainers/node
COPY --from z /path/to/z /target/path/to/bin
....

This approach may save me hours a month only by reducing build time, copy happens immediately, moreover because it's a docker image - this image won't be downloaded again and again - it will take it from cache.

So instead of minutes i spend now less than a second to copy 1 file.

Now let's get back to features. If feature is used ( this is how I understand ) - it will run install.sh in the already built image.

So image rebuild would defintely trigger all features reinstallation.

At same time only if we could to have another API from a feature definition where we could inject certain lines in a generated devcontainer Dockerfile - then this problem wouldn't exists.

We could insert RUN, COPY, FROM commands as we would do this in own custom Dcokerfile.

What do you think of this approach?

Thanks!

[ThePlenkov]

Actually I have one real example:

FROM mcr.microsoft.com/devcontainers/typescript-node:1-22-bookworm
COPY --from=cloudfoundry/cli /usr/local/bin/cf /usr/local/bin/cf

I'd like to achieve something like this with a feature without creating Dockerfile. Is it possible?