Target not overwritten when using features

[chrmarti]

Reported by @sajaysurya in microsoft/vscode-dev-containers#1519:

Currently the docker-from-docker feature doesn't support multistage Dockerfiles

Relates to: Remote - Containers

It works well with the following Dockerfile

FROM python:3.10.5 
RUN apt-get update -q \
    && apt-get install -q -y --no-install-recommends \
        sudo
# add non-root user with sudo access (sudo required by docker-from-docker feature)
RUN adduser vscode
RUN echo vscode ALL=\(root\) NOPASSWD:ALL > /etc/sudoers.d/vscode \
    && chmod 0440 /etc/sudoers.d/$USERNAME
USER vscode

and the following .devcontainer.json file

        "dockerFile": "Dockerfile",
        "containerUser": "vscode",
	"features": {
		"docker-from-docker": {
			"version": "latest"
		}
	}

It actually works with a named stage in the Dockerfile like

FROM python:3.10.5 AS vscode_dev
RUN apt-get update -q \
    && apt-get install -q -y --no-install-recommends \
        sudo
# add non-root user with sudo access (sudo required by docker-from-docker feature)
RUN adduser vscode
RUN echo vscode ALL=\(root\) NOPASSWD:ALL > /etc/sudoers.d/vscode \
    && chmod 0440 /etc/sudoers.d/$USERNAME
USER vscode

as long as the build target in not explicitly mentioned in the .devcontainer.json file

        "dockerFile": "Dockerfile",
	"build": { "target": "vscode_dev" }, <--- NOTE: works without this line!
        "containerUser": "vscode",
	"features": {
		"docker-from-docker": {
			"version": "latest"
		}
	}

[chrmarti]

PR #121 up for review.

[chrmarti]

Fix is available in Dev Containers CLI 0.10.1, 0.12.0 and Remote-Containers 0.245.1 and 0.248.0-pre-release.

[rzhao271]

I'm unable to repro the original issue on Windows with older Remote-Containers versions. What are some verification steps for this issue?

[chrmarti]

@rzhao271 Thanks for the ping, the following show repro and verify it:

With the following with 0.247.0-pre-release there is no gh command in the dev container, with the fix in later versions gh is available:

devcontainer.json:

{
	"build": {
		"dockerfile": "Dockerfile",
		"target": "vscode_dev"
	},
	"features": {
		"github-cli": "latest"
	}
}

Dockerfile:

FROM ubuntu:latest AS vscode_dev