Wrong build context path in existing container template

[holms]

• VSCode Version:

holms@debian ~/D/c/s/app-prebid-config> code-insiders --version
1.44.0-insider
2aae1f26c72891c399f860409176fe435a154b13
x64

• Local OS Version: Debian latest
• Name of Dev Container Definition with Issue: go

Steps to Reproduce:

1. Create custom Dockerfile in .devcontainer folder.
2. Uncomment step which says context: . in .devcontainer/docker-compose.yml

   vscode-dev-containers/containers/docker-existing-docker-compose/.devcontainer/docker-compose.yml

   Lines 18 to 21 in bf82fa0

   	# Uncomment if you want to add a different Dockerfile in the .devcontainer folder
   	# build:
   	# context: .
   	# dockerfile: Dockerfile

3. Launch docker-compose -f docker-compose.yml -f .devcontainer/docker-compose.yml build
4. See the world burn: ERROR: Cannot locate specified Dockerfile: Dockerfile

This seems to be a bug in a docker-compose. I've already registered in here: docker/compose#7350

I'm not sure is this indented behavior, or not. What is happening is that if you'd do docker-compose -f docker-compose.yml -f .devcontainer/docker-compose.yml config you'd see build context showing to a folder where docker-compose.yml is located, although in my opinion context should point to CWD of the config which overrides previous one. I'm pretty sure you've though it's using CWD (or maybe it was working this way before).
This is an issue on RC and also latest stable release. So if I use your provided build context: . this won't work, Dockerfile won't be found, you need to put into build context this:./.devcontainer/, then it works fine.

Here's first config docker-compose.yml

 app-prebid-config:
        container_name: app-prebid-config
        build:
            context: app 
            dockerfile: Dockerfile
        volumes:
            - ./app:/app/prebid-config

Here's .devcontainer/docker-compose.yml

version: '3.7'
services:
    app-prebid-config:
        build:
            context: .
            dockerfile: Dockerfile
        volumes:
            - ./app:/workspace:cached
        cap_add:
            - SYS_PTRACE
        security_opt:
            - seccomp:unconfined
        command: /bin/sh -c "while sleep 1000; do:; done"

Now let's see what config command shows:

$ docker-compose  --project-name app-prebid-config -f docker-compose.yml -f .devcontainer/docker-compose.extend.yml  config
....
  app-prebid-config:
    build:
      context: /home/holms/Dev/contracts/setupad/app-prebid-config
      dockerfile: Dockerfile
...

And of course the build would fail:

holms@debian ~/D/c/s/app-prebid-config> docker-compose  --project-name app-prebid-config -f docker-compose.yml -f .devcontainer/docker-compose.extend.yml  build
Building app-prebid-config
ERROR: Cannot locate specified Dockerfile: Dockerfile

As no Dockerfile exist near docker-compose.yml. And I believe anyone would want to use .devcontainer/Dockerfile in the first place in your overriden docker-compose config, as it contains all custom tools for debuging golang specifically for vscode. In docker-compose.yml I'm using default Dockerfile location which is a Dockerfile for CI only, and checking it it's builds locally is quite healthy for a developer I believe after coding job is done, at least checking does it compile on a build stage is extremely useful.

Also created this issue in release microsoft/vscode-remote-release#2681 but I'm not sure if it's their fault, it's this template fault or docker-compose itself.
This btw might be related: #247

[holms]

@chrmarti who can I discuss this with :)?

[Chuxel]

This appears to be a common question for Docker Compose. See docker/compose#3530 (comment)

In effect, the build path in the override is relative to the first file in the array in devcontainer.json. So, while the dev container can't be updated to guarantee the path is correct when un-commented, we can update the template with this detail.

[holms]

Interesting.. Probably updating devcontainer.json with a proper sequence would make sense. I've got this command failing when using your repo out of the box :)

[Chuxel]

Yeah I've got an update queued I'm about to push. I'll also add some text to this effect to docs.

    # Uncomment if you want to use a different Dockerfile in the .devcontainer folder.
    # Note that the path of the Dockerfile and context is relative to the *primary* 
    # docker-compose.yml file (the first in the devcontainer.json dockerComposeFile array). 
    # The sample below assumes your primary file is in the root of your project.
    #
    # build:
    #   context: .
    #   dockerfile: .devcontainer/Dockerfile