devcontainers

[AshFungor]

Hey,

Here is my proposal for devcontainers.
Folder structure:

• devcontainers
  • build.py - script to handle cmake configure & build, plus optionally conan setup and some minor jobs as well
  • setup.py - this script creates necessary configuration for VSCode
  • conanfile.py - recipe for conan
  • templates - folder for distribution-based configs (dockerfiles and conan profiles)

build.py is optional here, one might just use regular CMake commands to achieve the same result. Conan is optional, too - template images should provide required packages. Although I suppose it is a good idea to allow picking specific versions with it.

@riebl, I would appreciate your feedback on this structure.

[AshFungor]

All scripts are ready now, same as images.

Each template folder has Dockerfile for respective container and sample conan profile. Unfortunately, the variety of platforms and system setups makes it almost impossible to write universal profile, so these ones are kind of references.

Conan is not a must to use anyway, images are built with all dependencies satisfied.

I've added docs to each piece, tested it with common uses. Sadly, as you mentioned, maintaining this is tough and I don't see an easy way to automate testing for now.

Let me know your thoughts, @riebl.

[riebl]

Thanks for your efforts! It looks quite good after a first quick checkup. Please give me some more time, because I would like to play with it as soon as I am back from my business trip.

Does it have any particular benefit to support multiple base images for the DevContainer setup?
Could the maintenance effort be reduced by just using a minimal base image and relying entirely on Conan for a full build environment?
Though not critical for DevContainers, the Dockerfiles could benefit from a multi-stage approach. Furthermore, removing stuff from the container images in separate RUN steps still "bloats" the overall image size. But as I said, that is not critical for the moment.

[AshFungor]

Of course, no problem :)

1. Base images. I had initial idea of supporting several popular distributions for convenience, but now I realize that we probably just need stable and rolling release to meet most people's needs. I tested both Debian and Arch Linux image on my Arch Linux machine and they all worked just fine. Considering Debian has unstable releases too, we can just leave Arch Linux image out, if you prefer it this way.

2. I'm glad you mentioned conan. To be honest, I don't like forcing people into using specific tool, unless there is no other choice. Conan is a wonderful tool if you know what are you doing, but someone might not be used to it, so providing dependencies system-wide might be a good approach.
   By the way, should I make a setting for separate volume for conan folder? Stopping container clears default path for conan folder (defined as CONAN_HOME) and upon VSCode reloading you have to compile everything again. One might set CONAN_HOME to point somewhere in build directory, so changes are persisted on host machine, but I don't know, seems counter-intuitive a bit.

3. I think we might just remove that rm -r at this point, it takes quite some time in build process and yields no benefits. We can also move package cache clear command in base stage, too.

4. Sorry, I didn't get your point about multi-stage builds? :) I thought mine are multistaged

[AshFungor]

Looks like mounting XAUTHORITY temporary file was a bad idea since it is generated on boot with random name, and docker does not allow recreating mounts. The only solution I found was this:
microsoft/vscode-remote-release#9955 (comment)

Also did 3) #358 (comment)

[AshFungor]

By the way: VSCode resets extensions in devcontainer on every reload unless you specify them like this:

"customizations": {
        "vscode": {
            "extensions": [
                "ms-python.vscode-pylance",
                "waderyan.gitblame",
                "twxs.cmake",
                "llvm-vs-code-extensions.vscode-clangd"
            ]
        }
    }

You can add them with Extensions UI, too :)