Old Ruby and Rails on new hardware with dev containers

Need to work on an older Ruby or Rails application on newer hardware? Here’s how I got Ruby 2.1 (end of life: 2017) and Rails 4.0 running in a Visual Studio Code dev container on my Apple Silicon Mac, so I can actually start updating the app.

The hang-ups were installing an older OpenSSL on a newer Ubuntu image, making sure it would install in an ARM Linux container, and working around some rvm permissions jankiness. I’m guessing you can tweak it for other Ruby versions supported by rvm. Works on my machine; works for at least one of my coworkers, too.

Here’s the .devcontainer/Dockerfile I eventually landed on. Maybe room for improvement, but my goal was to get this old application running quickly:

FROM mcr.microsoft.com/devcontainers/base:jammy

# Install basic requirements
RUN apt-get update && apt-get install -y \
    curl \
    gnupg2 \
    build-essential \
    procps \
    nodejs \
    && rm -rf /var/lib/apt/lists/*

# Install RVM
RUN gpg2 --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB \
    && curl -sSL https://get.rvm.io | bash -s stable

# Create directory for SSL packages
RUN mkdir -p /tmp/libssl

# Download SSL packages
WORKDIR /tmp/libssl
RUN curl -sSLO http://ports.ubuntu.com/ubuntu-ports/pool/main/o/openssl1.0/libssl1.0.0_1.0.2n-1ubuntu5.13_arm64.deb \
    && curl -sSLO http://ports.ubuntu.com/ubuntu-ports/pool/main/o/openssl1.0/libssl1.0-dev_1.0.2n-1ubuntu5.13_arm64.deb

# Remove conflicting packages
RUN apt-get remove -y libcurl4-openssl-dev libssl-dev || true

# Install SSL packages
RUN dpkg -i /tmp/libssl/libssl1.0.0_1.0.2n-1ubuntu5.13_arm64.deb
RUN dpkg -i /tmp/libssl/libssl1.0-dev_1.0.2n-1ubuntu5.13_arm64.deb

# Cleanup
RUN rm -rf /tmp/libssl
WORKDIR /

# Install Ruby 2.1
SHELL ["/bin/bash", "-c"]
RUN source /etc/profile.d/rvm.sh \
    && rvm install 2.1.1 \
    && rvm use 2.1.1 --default

# Optionally reinstall libcurl4-openssl-dev if needed
RUN apt-get update && apt-get install -y libcurl4-openssl-dev \
    && rm -rf /var/lib/apt/lists/*

# Setup RVM for vscode user
RUN usermod -aG rvm vscode \
    && echo 'source /etc/profile.d/rvm.sh' >> /home/vscode/.bashrc \
    && echo 'source /etc/profile.d/rvm.sh' >> /home/vscode/.zshrc

# Make sure RVM is available in non-login shells
RUN echo 'source /etc/profile.d/rvm.sh' >> /etc/bash.bashrc

# Set proper permissions
RUN chown -R vscode:vscode /usr/local/rvm

And its corresponding .devcontainer/devcontainer.json:

{
    "name": "Ruby 2.1 Development",
    "build": {
        "dockerfile": "Dockerfile"
    },
    "customizations": {
        "vscode": {
            "extensions": [
                "rebornix.Ruby"
            ]
        }
    },
    "remoteUser": "vscode",
    "features": {
        "ghcr.io/guiyomh/features/just:0": {}
    }
}

Commentary

• I did this work with help from Anthropic’s Claude 3.5-sonnet model: First as a conversation about how to get things working inside the container, then to port it a proper Dockerfile. Maybe spent an hour on this in total? Most of that time was on getting the OpenSSL packages to compile and install correctly.
• I erred on the side of a full-blown Ubuntu distribution over a smaller Ruby image. It’s slower to build, but I know it’s got pretty much all the build tools I need. And the Dockerfile isn’t used for production, so it can be a little oversized.
• I went with rvm primarily because I knew that, with the proper Ubuntu packages, it could install an older Ruby. I can also use it to install newer Rubies, step by step, for upgrades. You could try rbenv or compiling the Ruby, if you’d like.
• You may notice I included just as an add-on feature to the dev container. Not necessary, but I like having a consistent developer UI, regardless of a code base’s age.

Discussion