codespaces dockerfile copy fails

Question

I am trying to learn codespaces and I have the following dockerfile:

FROM mcr.microsoft.com/vscode/devcontainers/base:debian-11

RUN apt update -y; \
    apt install python3-pip -y

COPY .devcontainer/req.txt /usr/local/bin/.
RUN pip3 install --no-cache-dir -r /usr/bin/req.txt

but bizzarely the copy always seem to fails with this error:

#9 ERROR: failed to walk /var/lib/docker/tmp/buildkit-mount3300366747/.devcontainer: lstat /var/lib/docker/tmp/buildkit-mount3300366747/.devcontainer: no such file or directory

What is going on? I am baffled!

When I look at the rescue container, I do see the file intact under .devcontainer

my tree is lie so:

-src
    -.devcontainer
        -Dockerfile
        - devcontainer.json
        - req.txt
    - main.py

and in my devcontainer.json, I have:

// For format details, see https://aka.ms/devcontainer.json. For config options, see the
// README at: https://github.com/devcontainers/templates/tree/main/src/debian
{
    "name": "Debian",
    // Or use a Dockerfile or Docker Compose file. More info: https://containers.dev/guide/dockerfile
    // "image": "mcr.microsoft.com/devcontainers/base:${templateOption:imageVariant}"
    "build": {
        // Path is relataive to the devcontainer.json file.
        "dockerfile": "Dockerfile"
    }
    // Features to add to the dev container. More info: https://containers.dev/features.
    // "features": {},

    // Use 'forwardPorts' to make a list of ports inside the container available locally.
    // "forwardPorts": [],

    // Configure tool-specific properties.
    // "customizations": {},

    // Uncomment to connect as root instead. More info: https://aka.ms/dev-containers-non-root.
    // "remoteUser": "root"
}

Answer 1

Looking at your posted directory structure, I see that your Dockerfile is actually inside the .devcontainer directory you are referring to in your COPY command. That's not allowed, so either

• Change your command to COPY req.txt /usr/local/bin/

or

• Move your Dockerfile one directory up and call docker build from there (note, that moving your docker file may break other steps of your build chain)