Jekyll Docker Setup

This document outlines the process for setting up a local development environment for this Jekyll site using Docker. This approach encapsulates the Ruby dependency within a container, avoiding a system-wide installation.

Goal

To run the Jekyll site locally for testing and development without installing Ruby and its dependencies directly on the host machine.

Solution

We use Docker to create a containerized environment for the Jekyll site. A Dockerfile defines the environment, and a docker-compose.yml file makes it easy to manage the development server.

1. Dockerfile

This file instructs Docker on how to build the image. It starts with a Ruby base image, installs necessary packages, installs the gems specified in the Gemfile, and then sets the command to run the Jekyll server.

# Use the official Ruby image.
FROM ruby:3.1-slim

# Set the working directory
WORKDIR /usr/src/app

# Install dependencies
RUN apt-get update && apt-get install -y build-essential

# Copy Gemfile and Gemfile.lock
COPY Gemfile Gemfile.lock ./

# Install gems
RUN bundle install

# Copy the rest of the application
COPY . .

# Expose the port Jekyll runs on
EXPOSE 4000

# Serve the site
CMD ["bundle", "exec", "jekyll", "serve", "--host", "0.0.0.0"]

2. Docker Compose

The docker-compose.yml file simplifies the process of running the container. It specifies the port mapping and mounts the current directory as a volume, which allows Jekyll’s live-reloading feature to work.

services:
  jekyll:
    build: .
    ports:
      - "4000:4000"
    volumes:
      - .:/usr/src/app

3. .dockerignore

A .dockerignore file was also added to prevent files like .git, the _site build directory, and the Docker files themselves from being unnecessarily copied into the build context, keeping the image smaller and build times faster.

Usage

With Docker and Docker Compose installed, the local server can be started with a single command from the project root:

docker-compose up

The site will be available at http://localhost:4000.