Using a public GIT-Hub repository (that was a homework of my group) in my Bachelor thesis I have a question concerning my special case.

In my bachelor thesis, I must implement a CI (e.g. Jenkins) server and show its functionality based on a sample project. This work is handed to other students in order to let them try out the technology.

There are many projects available which I could use as a sample project on Git Hub but I wanted to have a simple one and thus I have chosen a Git Repo containing a former homwework (a small game) that I have written with colleagues. I know that public Git Repos are basically Open Source but still I have questions.

Questions: 


Do I have to mention my colleagues, who implemented that homework
with me, explicitly in my Bachelor Thesis?
Do I need my colleagues agreement that I can use this project for my
Bachelor Thesis?
Does it make any legal difference if I provide a link directly to
this sample project or if the project is just visible in
screenshots without showing an explicit URL?
Do I have to mention my colleagues, who implemented that homework with me, explicitly in my Bachelor Thesis?


Depends on what referencing system your given institute uses. Most likely, it would be a good idea to mention that in your reference. For example, if you are using the Harvard system:

[Surname], [First-name] et al [System (e.g. Github)] [Year of creation], [Repository Name], [Version #], [Type of 'thing'], accessed [Access date], [Repository URL]



  Do I need my colleagues agreement that I can use this project for my Bachelor Thesis?


As long as you correctly reference it, and that you don't use it commercially you should be fine, but just doing something like emailing them asking if you can use it as an example for your assignment would do no harm.


  Does it make any legal difference if I provide a link directly to this sample project or if the project is just visible in screenshots without showing an explicit URL?


Legal difference? Yes. If it would ever come to such, giving the actual URL would/could effectively protect you, as the opposition could claim that you edited the screenshots or that they weren't of the correct repository in the first place. 



To be honest, I would prefer to have a few extra words in my bibliography rather than be taken to court and be prosecuted.