Dockering Your IT Journey

By Amr and Co-pilot

How to use Docker to run Jekyll with Ruby 2.7

Estimated reading time: 14 minutes

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Dockering Your IT Journey

• • 12 min read • Updated: April 02, 2024
Docker Jekyll Ruby

bamr87: i need to update this dockerfile to run this repository in a container.

GitHub Copilot: Sure, to run a repository in a Docker container, you need to clone the repository into the Docker image. Here’s an example of how you can modify your Dockerfile to do this:

# syntax=docker/dockerfile:1
# escape=\
# Directives as above need to be before comments and builder instruction.
# Documentation found here: https://docs.docker.com/engine/reference/builder/
FROM alpine:latest as builder

# Install git
RUN apk add --no-cache git

# Clone the repository
RUN git clone https://github.com/yourusername/yourrepository.git

FROM scratch

# Copy the repository contents from the builder image
COPY --from=builder /yourrepository /yourrepository

CMD ["/hello"]

# Test run
RUN echo 'we are running some # of cool things'

Please replace https://github.com/yourusername/yourrepository.git with the URL of your repository. This Dockerfile uses a multi-stage build. The first stage is a temporary image (named “builder”) that includes Git to clone the repository. The second stage is the final image, which copies the cloned repository from the builder image.

bamr87: this container is for a local build based on the source code of the local repository.

GitHub Copilot: If you want to build a Docker image based on the source code of a local repository, you don’t need to clone the repository. Instead, you can copy the source code directly into the Docker image. Here’s how you can modify your Dockerfile:

# syntax=docker/dockerfile:1
# escape=\
# Directives as above need to be before comments and builder instruction.
# Documentation found here: https://docs.docker.com/engine/reference/builder/
FROM alpine:latest

# Copy the local repository contents into the Docker image
COPY . /app

# Change working directory
WORKDIR /app

# If you have a build command, add it here
# RUN your-build-command

CMD ["/hello"]

# Test run
RUN echo 'we are running some # of cool things'

This Dockerfile copies the contents of the local repository (the current directory) into the /app directory of the Docker image. If you have a build command, you can add it after the COPY command. The WORKDIR command changes the working directory to /app, so all subsequent commands will be run in this directory.

bamr87: How can I build and run the Docker image using the updated Dockerfile?

GitHub Copilot: You can build and run the Docker image using the Docker CLI. Here are the commands you need to run in your terminal:

# Build the Docker image
docker build -t my-app .

# Run the Docker image
docker run -p 8080:8080 my-app

In the docker build command, -t my-app names the Docker image “my-app”, and the . specifies that the Dockerfile in the current directory should be used.

In the docker run command, -p 8080:8080 maps port 8080 in the Docker container to port 8080 on your machine. Replace “8080” with the port your app is configured to use if it’s different.

“my-app” is the name of the Docker image to run. Replace “my-app” with the name you used in the docker build command if it’s different.

bamr87: how do i create an image for this repo?

GitHub Copilot: To create a Docker image for your repository, you can use the docker build command. Open your terminal and navigate to the directory containing your Dockerfile. Then, run the following command:

docker build -t my-app .

This command tells Docker to build an image using the Dockerfile in the current directory (denoted by the .) and tag the image with the name “my-app”. You can replace “my-app” with whatever name you want to give your Docker image.

After running this command, Docker will execute each command in the Dockerfile in order, creating a Docker image. If the build is successful, the image will be stored locally on your machine and can be listed by running docker images.

bamr87: what should be in the docker file?

GitHub Copilot: The Dockerfile you provided is almost complete for a basic setup. However, there are a few things you might want to add or change depending on your application’s requirements:

  1. Base Image: You’re using alpine:latest as your base image, which is a minimal Docker image based on Alpine Linux. If your application requires a specific environment, you might need to use a different base image.

  2. Copy Command: You’re copying the entire contents of your current directory into the Docker image. This is fine for a simple application, but for larger applications, you might want to only copy the necessary files and directories.

  3. Work Directory: You’re setting the working directory to /app, which is good practice.

  4. Build Command: You’ve commented out a placeholder for a build command. If your application requires a build step (like compiling source code), you should uncomment this line and replace your-build-command with the actual build command.

  5. Command: You’re running CMD ["/hello"], which Docker will execute when the container starts. This should be replaced with the command to start your application.

  6. Test Run: You’re running echo 'we are running some # of cool things' as a test run. This line doesn’t have any effect on the built image and can be removed.

Here’s an example of how you might modify your Dockerfile for a Node.js

bamr87: starting from scratch, what should be in this file for this jekyll app

GitHub Copilot: For a Jekyll application, you would need a Dockerfile that installs the necessary dependencies and builds your site. Here’s a basic example:

# Use an official Ruby runtime as a parent image
FROM ruby:2.7

# Install Node.js
RUN apt-get update -qq && apt-get install -y nodejs

# Install Jekyll and Bundler
RUN gem install jekyll bundler

# Set the working directory in the container to /app
WORKDIR /app

# Add the current directory contents into the container at /app 
ADD . /app

# Install any needed packages specified in Gemfile
RUN bundle install

# Make port 4000 available to the world outside this container
EXPOSE 4000

# Run Jekyll when the container launches
CMD ["jekyll", "serve", "--host", "0.0.0.0"]

This Dockerfile does the following:

  1. Uses the official Ruby 2.7 image as a base.
  2. Installs Node.js, which is a runtime required for Jekyll.
  3. Installs Jekyll and Bundler.
  4. Sets the working directory in the Docker image to be /app.
  5. Copies the current directory (i.e., your Jekyll site) into the Docker image.
  6. Installs any Ruby dependencies specified in your Gemfile.
  7. Exposes port 4000, which is the default port that Jekyll serves on.
  8. Sets the default command to serve the Jekyll site.

bamr87: @terminal #terminalLastCommand

GitHub Copilot: The error message in your terminal output indicates that the gem install jekyll bundler command failed because the versions of sass-embedded and bundler it’s trying to install require a Ruby version >= 3.0.0, but the Ruby version in your Docker image is 2.7.8.225.

To fix this, you can use a newer Ruby base image in your Dockerfile. Here’s an updated version of your Dockerfile using Ruby 3.1:

# Use an official Ruby runtime as a parent image
FROM ruby:3.1

# Install Node.js and Yarn
RUN apt-get update -qq && apt-get install -y nodejs npm && npm install --global yarn

# Install Jekyll and Bundler
RUN gem install jekyll bundler

# Set the working directory in the container to /app
WORKDIR /app

# Add the current directory contents into the container at /app 
ADD . /app

# Install any needed packages specified in Gemfile
RUN bundle install

# Install any needed packages specified in package.json
RUN yarn install

# Make port 4000 available to the world outside this container
EXPOSE 4000

# Run Jekyll when the container launches
CMD ["jekyll", "serve", "--host", "0.0.0.0"]

This Dockerfile does the following:

  1. Uses the official Ruby 3.1 image as a base.
  2. Installs Node.js, npm, and Yarn, which are runtimes required for Jekyll and your JavaScript code.
  3. Installs Jekyll and Bundler.
  4. Sets the working directory in the Docker image to be /app.
  5. Copies the current directory (i.e., your Jekyll site) into the Docker image.
  6. Installs any Ruby dependencies specified in your Gemfile.
  7. Installs any JavaScript dependencies specified in your package.json.
  8. Exposes port 4000, which is the default port that Jekyll serves on.
  9. Sets the default command to serve the Jekyll site.

bamr87: I must use Ruby 2.7.

GitHub Copilot: If you must use Ruby 2.7, you can specify the versions of Jekyll and Bundler that are compatible with Ruby 2.7 in your Dockerfile. Here’s how you can modify your Dockerfile:

# Use an official Ruby runtime as a parent image
FROM ruby:2.7

# Install Node.js
RUN apt-get update -qq && apt-get install -y nodejs

# Install specific versions of Jekyll and Bundler that are compatible with Ruby 2.7
RUN gem install jekyll -v 3.9.0 && gem install bundler -v 1.17.3

# Set the working directory in the container to /app
WORKDIR /app

# Add the current directory contents into the container at /app 
ADD . /app

# Install any needed packages specified in Gemfile
RUN bundle install

# Make port 4000 available to the world outside this container
EXPOSE 4000

# Run Jekyll when the container launches
CMD ["jekyll", "serve", "--host", "0.0.0.0"]

In this Dockerfile, gem install jekyll -v 3.9.0 installs Jekyll version 3.9.0 and gem install bundler -v 1.17.3 installs Bundler version 1.17.3. These versions are compatible with Ruby 2.7. You may need to adjust these versions depending on your application’s requirements.

bamr87: @terminal #terminalLastCommand

GitHub Copilot: The error message in your terminal output indicates that the gem install github-pages command failed because the nokogiri gem it’s trying to install requires a Ruby version >= 3.0, but the Ruby version in your Docker image is 2.7.4.191.

Since you must use Ruby 2.7, you can specify the versions of github-pages and nokogiri that are compatible with Ruby 2.7 in your Dockerfile. Here’s how you can modify your Dockerfile:

# Use an official Ruby runtime as a parent image
FROM ruby:2.7

# Install Node.js
RUN apt-get update -qq && apt-get install -y nodejs

# Install specific versions of github-pages and nokogiri that are compatible with Ruby 2.7
RUN gem install nokogiri -v 1.11.7 && gem install github-pages -v 209

# Set the working directory in the container to /app
WORKDIR /app

# Add the current directory contents into the container at /app 
ADD . /app

# Install any needed packages specified in Gemfile
RUN bundle install

# Make port 4000 available to the world outside this container
EXPOSE 4000

# Run Jekyll when the container launches
CMD ["jekyll", "serve", "--host", "0.0.0.0"]

In this Dockerfile, gem install nokogiri -v 1.11.7 installs nokogiri version 1.11.7 and gem install github-pages -v 209 installs github-pages version 209. These versions are compatible with Ruby 2.7. You may need to adjust these versions depending on your application’s requirements.

bamr87: write me a short set of instructions in markdown format of the build and deployment instructions using docker.

GitHub Copilot: Sure, here are the build and deployment instructions using Docker in Markdown format:

# Build and Deployment Instructions

## Building the Docker Image

1. Open your terminal.
2. Navigate to the directory containing your Dockerfile.

cd /path/to/your/dockerfile

3. Build the Docker image. Replace `my-app` with the name you want to give your Docker image.

docker build -t my-app .


## Running the Docker Container

1. Run the Docker container. Replace `my-app` with the name of your Docker image.

docker run -p 4002:4002 my-app

   This command maps port 4002 in the Docker container to port 4002 on your machine.

## Accessing the Application

1. Open your web browser.
2. Navigate to `http://localhost:4002`.

You should now see your Jekyll application running.

Please replace /path/to/your/dockerfile with the actual path to your Dockerfile, and my-app with the name you want to give your Docker image.

bamr87: you replace it with the actual path.

GitHub Copilot: The ADD . /app command in your Dockerfile is copying the contents of your current directory (where the Dockerfile is located) into the /app directory in the Docker image. If you want to copy from a specific path on your local machine, you can replace the . with the path to the directory you want to copy.

For example, if you want to copy the contents of the /path/to/your/app directory on your local machine, you can modify the ADD command like this:

# Add the contents of the /path/to/your/app directory into the container at /app 
ADD /path/to/your/app /app

Please replace /path/to/your/app with the actual path to the directory you want to copy.

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