Decide whether to base the devcontainer on `mcr.microsoft.com/devcontainers/python`

[coretl]

See https://github.com/devcontainers/images/tree/main/src/python

Pros:

• Already has zsh so should be a lot quicker to start a new devcontainer (with common-utils feature) - needs testing
• Contains additional tools like pipx

Cons:

• More change
• Another tie into Microsoft ecosystem

@callumforrester @garryod thoughts?

[garryod]

Don't think the tie in would be too strong, but generally prefer composition (features) instead of a monolithic base container. Then again, features can be rather slow

[callumforrester]

I agree with @garryod on tie in. The slowness of features has definitely reduces adoption in DAQ so it is something we're looking to do something about.

An alternative might be to build our own base image out of precisely the features we want and use that?

[coretl]

I think the microsoft one is precisely that, base python image with common-utils in it...

[coretl]

Benchmarking the existing container with just dev dependencies (python-copier-template-example):

• From "rebuild container without cache" to venv installed: 1m59s
• From "rebuild container" to venv installed: 1m19s

If we remove `common-utils":

• From "rebuild container without cache" to venv installed: 1m06s
• From "rebuild container" to venv installed: 36s
• But no zsh

If we switch to mcr.microsoft.com/devcontainers/python:

• From "rebuild container without cache" to venv installed: 1m43s
• From "rebuild container" to venv installed: 38s
• Need https://github.com/gilesknap/docker-outside-docker/blob/9ca46bf22c0daa11cebed1259a476e810b6ad550/.devcontainer/devcontainer.json#L36-L39
• And we get "WARNING: Running pip as the 'root' user can result in broken permissions" for some reason in the postCreateCommand even though the pip install in the terminal is ok

[coretl]

Also, most of the warm cache time is taken with 25s of pip install. This drops to 5s if we use uv pip install instead...

[gilesknap]

I think common utils is giving more than just zsh. Maybe.

• Do you get your ssh keys and github access inside the container without them?
• Also X11 forwarding may or may not work without common utils
• what about other git global config ?

We used to have manual workarounds for the above but I prefer the native MS approach if possible.

[gilesknap]

I think common utils is giving more than just zsh. Maybe.

• Do you get your ssh keys and github access inside the container without them?
• Also X11 forwarding may or may not work without common utils
• what about other git global config ?

We used to have manual workarounds for the above but I prefer the native MS approach if possible.

Above is not true as I tried it here https://github.com/gilesknap/docker-outside-docker/tree/no-common-utils.

If you do not use MS base image and remove common-utils feature you need only add an install of git and all of the above still work. So zsh is all you miss out on as far as I can tell. But I do like zsh these days.

[coretl]

One thing that helps massively is going back to how it was originally, removing the feature, and installing it manually in the Dockerfile:

RUN git clone https://github.com/devcontainers/features --depth=1 && USERNAME=none bash features/src/common-utils/install.sh

This means that it gets cached rather than being run each time.

• From "rebuild container without cache" to venv installed: 1m36s
• From "rebuild container" to venv installed: 35s

If we switch to uv too then then we can shave another 20s off this
The git clone is a hack, we should really be extracting from the OCI artifact at ghcr.io/devcontainers/features/common-utils:2, but I have no idea how to do that!
@garryod any ideas?

[garryod]

If we switch to uv too then then we can shave another 20s off this
The git clone is a hack, we should really be extracting from the OCI artifact at ghcr.io/devcontainers/features/common-utils:2, but I have no idea how to do that!
@garryod any ideas?

Not sure of the exact format of their OCI artifacts, but I expect oras pull is likely what you're after

[callumforrester]

One thing that helps massively is going back to how it was originally, removing the feature, and installing it manually in the Dockerfile:

@coretl would it be even faster if we did that and prebuilt it remotely and pulled from Github?

[coretl]

I would rather avoid maintaining a container build for every version of python we want to support that triggers a rebuild each time there are security updates... If we only pay the 1min cost on first run of the dev container that doesn't seem too bad to me...

If we want to go down the container build root then we should use the devcontainers cli to make these in the copier template CI, but we need to work out when to trigger them...

[coretl]

Ok, here is the version with oras:

# Add common utils features
COPY --from=ghcr.io/oras-project/oras:v1.2.0 /bin/oras /bin/oras
RUN mkdir /tmp/common-utils \
    && cd /tmp/common-utils \
    && /bin/oras pull ghcr.io/devcontainers/features/common-utils:2 \
    && tar xvf devcontainer-feature-common-utils.tgz \
    && USERNAME=none ./install.sh

I'm now pretty certain this is not the right path to take. What we are after is a good out of the box experience that can be customized by the user (prompt, dotfiles, etc.). VSCode has 2 ways to do this, features and dotfile support.

Some possible routes:

1. Remove all features from the project, and provide instructions to add user features (and plugins) with at least one sensible default setup (based on zsh) that people can copy and paste with a prompt, completion and persistent history
2. As 1 but put some useful apt install commands in the dockerfile (like zsh) so that they are cached
3. As 1 but make the default setup based on bash instead

I've got a mild preference for 3, then shipping the result as a python-copier-template devcontainer feature, but then the question will be which prompt to use.

I'm also not sure how zsh completion works, and whether bash completion can be made to be as good as it with a bit of configuration...

@garryod @callumforrester @gilesknap @GDYendell thoughts?

[coretl]

Some useful links I found:

• A persistent bash history feature
• A minimal zsh feature
• A one-liner installer for zsh and oh-my-zsh that could go in a dotfile
• A suggestion that common-utils is too big and should be broken up

[callumforrester]

Hmm, sorry about this @gilesknap but I think we should drop ZSH. The rest of this template is very opinionated and goes the route of "there is one supported way to do this". Given that supporting ZSH and bash is already causing complexity I think we should only support one and it should be the one that more people are going to use.

[gilesknap]

Hmm, sorry about this @gilesknap but I think we should drop ZSH. The rest of this template is very opinionated and goes the route of "there is one supported way to do this". Given that supporting ZSH and bash is already causing complexity I think we should only support one and it should be the one that more people are going to use.

@callumforrester I totally agree. This discussion has made it clear that the only thing we are really getting from common-utils is zsh.