Git and GitLab

In case you are curious…

Git

Git is a version control system for text files (Yes, it can also track binary files (that is, non-text files)… but it is mainly used track text files!)

Git is extremely popular among computer programmers to facilitate collaboration and incremental software development.

That is, if you’ll ever need to work with a computer programmer it is very possible you’ll need to collaborate with her via GitHub (owned by Microsoft, 37M users) or GitLab (open-source), two of the most popular web-based services that use Git.

It is a good idea to have an basic understanding of what is Git and how it works (and also nice to have it on your CV!).

But first, what’s actually a text file?

What’s a text file?

Generally speaking, on your computer (and on every other computer around you) there are two types of files: text files and binary files.

A text file is a file that when opened with any text editor will be human-readable: characters ordered in lines.

A binary file is a file that when opened with a text editor will make no sense to most of us.

A text editor is a “computer program that edits plain text” (Wikipedia). Popular text editors are Notepad (Microsoft Windows) and TextEdit (macOS).

Is a Word file a text file?

No, it is not.

Although a Word file looks like a text file when opened in Microsoft Word, it is actually a collection of multiple files packaged together.

For this reason, Git is definitely not ideal to track changes (and versions) of a Word file.

Git, how to understand it

So how do we understand Git?

It is useful to consider Git as a computer program to maintain a systematic list of

1. Changes to a text file – so different chronological versions of the same file.

2. Parallel versions of a text file – so different synchronous versions of the same file.

Wait, what?

Welcome to Git

Let’s step into Git-world and see if we can make sense of it.

We’ll introduce key Git terminology and basic git commands.

Commands are actions that you command git to take. For example,

git init

will initiate a new git repository in the current directory.

So, what’s a repository?

Repository

In Git-world everything is contained by a repository, or a repo for short.

You can think of a Git repository as a directory with a bunch of files and subdirectories. If you decide to use Git for your project, a repository will likely contains all your files.

Chronological versions of a file (Git workflow)

Let’s say that you have a file my_file.txt that you want to track.

You can add the file to your repository simply with

git add my_file.txt

And every time you want to commit a new version of the file to your repository you do

git commit

Parallel versions of a file (Git workflow)

Now let’s say that both Alice and Bob wants to work on the same file at the same time.

Both can then create a branch of the project with

git checkout -b my_branch

and finally merging it into the same project with

git merge my_branch

GitLab

GitLab is a Git-repository hosting and management service. It offers a number of features such as managing projects (members, wikis, discussions, etc.), Git repositories, issues and merge requests.

You might want to create a GitLab profile to store and publish your code portfolio. You can also opt to use the very similar GitHub (github.com) instead, but GitLab UTS will offer you the option to keep your repositories private, something that on GitHub is only an option for pro users.

1. How to create your GitLab profile

To create your own GitLab profile you need to visit code.research.uts.edu.au/users/sign_in and enter your UTS credentials.

After creating your profile, you can create a new project or cloning an existing Git repository into your new project.

Project or Repository?: In general, we can consider projects and repositories to be the same thing: A project is a repository and a repository is a project. Yet, in GitLab projects adds additional features to a standard Git repository, so a project will be a repository plus something.

2. How to create a new project

1. From your GitLab dashboard, just click on “New project”.

1. In the “Blank project” tab, enter a “Project name” and decide if your project is going to be “Private” (only authorised users can access it), “Internal” (every UTS users can view it) or “Public” (everyone can view it).

2. Finally, click on “Create project” and your done! (Your repository is empty though: you’ll need to add your files).

3. How to clone an existing repository into a new project

Among the most powerful features of Git there is cloning. Cloning is different from branching as it creates an independent repository that you can manage and modify as you see fit.

1. From your GitLab dashboard, again click on “New project”.

2. Now select the “Import project tab” and click on “git Repo by URL”.

1. You need now to enter this URL in the “Git repository URL”: (for example, https://code.research.uts.edu.au/143852/code-as-literacy-jupyter-notebooks.git, but the point is: it can be any URL pointing to a Git repository!)

2. Since you are also creating a new project, you need to define its “Project name” and “Visibility level” as before.

3. After clicking on “Create project”, GitLab will take care of cloning the project. After that, you can inspect the files that have been added to your project and that you can now modify.

4. How to use GitHub Desktop with GitLab

The GitLab web interface allows to manage and edit your project files directly from your browser. Still if your project involve code, you might want to also be able to edit and run your files locally on your machine.

GitHub Desktop (available for both macOS and Windows) facilitates synchronising your local Git repository with GitLab (or clearly GitHub.com).

You can refer to this page to download and install GitHub Desktop (which is free).

Once GitHub Desktop is installed you will need to add a Git repository. You now have three options:

1. Clone an existing repository;
2. Create a new repository;
3. Add an existing repository.

Let’s clone our existing repository hosted on GitLab.

Cloning a GitLab repository with GitHub Desktop

To clone a GitLab repository, you will need to indicate a directory on your computer where to store the repository (“Local path”) and crucially the URL of the existing repository on GitLab (or wherever) you want to clone. To get the URL of your GitLab repository, you can simply copy the URL you see in your browser when you are on the project and add a .git to its end.

The URL will be something like https://code.research.uts.edu.au/143852/code-as-literacy-jupyter-notebooks.git, but instead of 143852 your UTS number and instead of code-as-literacy-jupyter-notebooks the slug identifying your project.

Commit and push changes to GitLab with GitHub Desktop

Once you have created the local repository, which is linked to the online repository, every time you modify a file and after you commit its new version with the “Commit to master” button, you can push the new version to the online repository for everyone to see. Just remember that you will need to authenticate with your UTS credentials.