To get started, we will use this bookdown example, which is a minimal example of a book that can be hosted and edited on GitLab.

1. Go to https://gitlab.com/dashohoxha/bookdown-example and fork it. It will be automatically published on the address https://<username>.gitlab.io/bookdown-example/ (but you may have to wait for a few minutes). For more details on why and how this works check the next section.
2. Go to the "Settings" of the project and change the "Project name". Expand the "Advanced" section and change the project path as well.
3. Edit index.Rmd and change any fields, like: title:, author:, date:, url: and description:.
4. Edit _bookdown.yml and change the field book_filename:.
5. Change and modify the *.md files, and don't forget to update _bookdown.yml as well with the names of the new files.
6. Optionally, you may also experiment with changing the look and layout of the book by customizing index.Rmd. For more details about the available options make sure to read:
   • https://bookdown.org/yihui/bookdown/html.html
   • https://bookdown.org/yihui/bookdown/yaml-options.html

You have already seen (in the previous section) that whenever you make changes to the GitLab project https://gitlab.com/<username>/<book-title>.git, the book is automatically published and updated on the URL address https://<username>.gitlab.io/<book-title>/. How does it happen?

The key to understanding this is the file .gitlab-ci.yml, which has a content like this:

image: dockerscripts/bookdown

pages:
  script:
  - ./render.sh
  artifacts:
    paths:
    - public
  only:
  - master

This file instructs the CI/CD (Continuous Integration and Development) system of GitLab to do something whenever the content of the project is updated (for example some commits are pushed or a Merge Request is accepted).

The line image: dockerscripts/bookdown tells it to start a Docker container based on the image dockerscripts/bookdown.

The field pages: tells it that this CI/CD job is about generating the GitLab pages for this project. The content of the field shows how to do it. Basically, in plain English, it says something like this:

• Clone the branch master of the project inside the Docker container,
• then run the script ./render.sh in it (which is expected to generate the directory public/ with the content of the website that should be published),
• then get the content of the directory public/ and publish it on the website of the project: https://<username>.gitlab.io/<book-title>/

You can check the page "CI/CD -> Pipelines" to see more details about the CI/CD jobs, whether they passed or failed, etc. This can be very useful especially when a job has failed, because you can also check the log messages and hopefully find out what was the problem.

If you want to use a custom domain for the book you can do this from "Settings -> Pages".

For example for the book http://dashohoxha.gitlab.io/101-problema-programimi/ I have used as custom domain http://p101.fs.al, which is much shorter and convenient.

The details are described on: https://gitlab.com/docker-scripts/bookdown

Let's summarize them quickly:

1. Install docker-scripts:

   apt install m4
   git clone https://gitlab.com/docker-scripts/ds /opt/docker-scripts/ds
   cd /opt/docker-scripts/ds/
   make install
   

2. Install wsproxy:

   ds pull wsproxy
   ds init wsproxy @wsproxy
   cd /var/ds/wsproxy/
   ds make
   

3. Install bookdown container:

   ds pull bookdown
   ds init bookdown @bookdown
   cd /var/ds/bookdown/
   ds make
   

4. Install the book bookdown-example:

   cd /var/ds/bookdown/
   git clone https://gitlab.com/dashohoxha/bookdown-example
   mv bookdown-example books/
   ds render books/bookdown-example
   ds site add mybook.example.org books/bookdown-example
   

5. Add on /etc/hosts this line:

   127.0.0.1 mybook.example.org
   

   Then open in browser: https://mybook.example.org.

You can edit books/bookdown-example/ with any editor that you like. Then, to update the page with the latest changes you run again ds render books/bookdown-example/. This will regenerate the content of the directory books/bookdown-example/public/, which is being served on https://mybook.example.org.

Alternatively, you can update/regenerate it like this:

ds shell
cd books/bookdown-example/
./render.sh

Since GitHub pages support only Jekyll and plain HTML pages, the most easy way to publish a bookdown book on GitHub is to generate the HTML pages locally, as described on the previous section, and to push them on GitHub. You can do it like this:

1. Edit the script books/bookdown-example/render.sh and add to it a command that creates an empty file named .nojekyll on the public/ directory:

   echo 'touch public/.nojekyll' >> books/bookdown-example/render.sh
   

   This will let GitHub know that the content of the public/ directory contains a plain HTML site, and it should not try to process it with Jekyll.

2. Regenerate the public/ directory which contains the HTML files and other files that compose the website of the book:

   ds render books/bookdown-example/
   

3. Remove the file .gitignore which prevents the directory public/ from being committed to Git, and commit this directory to Git:

   cd books/bookdown-example/
   cat .gitignore
   git rm .gitignore
   git add public
   git commit -m 'Add rendered book'
   git push
   

4. Go to your repository’s settings and under "GitHub Pages" change the "Source" to be *"master branch /public folder"* (as described in this GitHub help page).

To update the page, after making some changes, you have to regenerate the public/ directory with ds render books/bookdown-example/, and to commit and push its changes to GitHub.

It is also possible to build an auto-update system with Travis CI, which would update the website of the book whenever some changes to the markdown files are committed and pushed to GitHub. This automated way is described in this help page. However it is a bit complex and maybe not worth the trouble.

The format of the *.md and *.Rmd files is basically the Pandoc's Markdown syntax, which is described on this page as well: https://bookdown.org/yihui/bookdown/markdown-syntax.html

However bookdown supports some further extensions, which are mainly useful for math. These extensions are described on this page: https://bookdown.org/yihui/bookdown/markdown-extensions-by-bookdown.html

Besides these, the syntax of GitLab markdown is a bit different from that of Pandoc's Markdown. For example the delimiter of the math code on Pandoc's Markdown is a single dollar sign, like this: $a^2$, while that delimiter for GitLab Markdown is like this: $`a^2`$. These small differences are fixed automatically by the script render.sh, so that markdown files are rendered nicely both on the GitLab web interface and on the website of the book.