Demo 6: Collaboration Using Git and Remote GitHub Repositories

▶️ Play from the beginning (~40 minutes)

In this demonstration, I will explain how to use remote GitHub repositories for collaborative software development. As with the previous demos, I’ll focus on some common development tasks with remotes.

Here is a diagram that expands on the previous anatomy of a local repo to show a high-level structure of remote repos. Note that GitHub repos are “bare” in that they do not have working trees.

Because these are collaborative tasks, I will introduce two developers, Alice and Bob, to perform the tasks.

▶️ 1. Setting Push Mode

Both Alice and Bob perform this step. It saves a setting, so it is only necessary to do this step once.

▶️ Set default push mode to simple, which is the new default Git prefers (see git config --global push.default simple). If we don’t set this, we will get a lengthy warning message every time we push.

I will perform these steps with the repository I created in the previous two demos.

▶️ In a web browser, create a new repository on GitHub. It needs to be empty, so don’t add anything to it.
▶️ Follow the instructions given on the GitHub repo page regarding how to share an existing repo (see git remote ... and git push ...).
▶️ In a terminal, review the state of the local repo with attention to the remote branches that have been added (git remote and git log --graph --oneline --all --decorate).
▶️ From the GitHub repo’s webpage, enter the settings and add collaborators to the project.

▶️ 3. Connecting/Syncing to an Existing GitHub Repo

Both Alice and Bob perform these steps.

▶️ In a web browser, open the GitHub repo page.
▶️ Click the “Clone or download” button, and copy the HTTPS URL for the repo.
▶️ In a local terminal, clone the repo using the URL (see git clone ...).
▶️ Review the state of the working tree to confirm that it was downloaded.
▶️ Review the state of the repo with attention to the remote settings and branches (git remote and git log --graph --oneline --all --decorate).

▶️ 4. Pushing Changes to a Remote Repo - The Fast-Forward Merge Case

Only Alice performs these steps.

▶️ Make changes to the working tree.
▶️ Stage and commit the changes (see git add -A and git commit ...).
▶️ Review how the state of the repo has changed (see git log --graph --oneline --all --decorate).
▶️ Push the changes to the remote repo (see git push).
▶️ Review how the state of the repo has changed (see git log --graph --oneline --all --decorate).
▶️ In a web browser, review the GitHub repo page to see how it has changed.

▶️ 5. Pulling Changes from a Remote Repo - The Fast-Forward Merge Case

Only Bob performs these steps.

▶️ Review the state of the repo to confirm that it is out of date (see git log --graph --oneline --all --decorate).
▶️ Fetch the changes from the remote repo and merge them into the local repo (see git pull). This will result in a fast-forward merge.
▶️ Review the state of the repo to confirm that it has been updated (see git log --graph --oneline --all --decorate).

▶️ 6. Pushing Changes to a Remote Repo - The Merge-Conflict Case

▶️ Alice: Make changes to the working tree.
▶️ Alice: Stage and commit the changes (see git add -A and git commit ...).
▶️ Bob: Make changes to the working tree.
▶️ Bob: Stage and commit the changes (see git add -A and git commit ...).
▶️ Alice: Push the changes to the remote repo (see git push). This command should complete without error.
▶️ Bob: Attempt to push the changes to the remote repo (see git push). This command should fail with a merge conflict.
▶️ Bob: Fetch the changes from the remote repo and merge them into the local repo (see git pull). This command should report merge conflicts.
▶️ Bob: Update the working tree to remove the merge conflicts.
▶️ Bob: Stage and commit the changes (see git add -A and git commit ...).
▶️ Bob: Push the changes to the remote repo (see git push). This command should complete without error.
▶️ Alice: Fetch the changes from the remote repo and merge them into the local repo (see git pull).