From: Matt Davis Date: Fri, 22 Feb 2013 22:03:42 +0000 (-0500) Subject: Instructor notes for teaching git via collaboration on GitHub. X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=fda4a1a751211ccbf9deac1d5bea7d7f1ad0f033;p=swc-version-control-git.git Instructor notes for teaching git via collaboration on GitHub. The focus of the lesson is to have students contribute to a repo on GitHub in which we are building up a list of the things they are most interested in learning at the boot camp. Requires everyone have a good internet connection and that at least some of the participants sign up for GitHub. --- fda4a1a751211ccbf9deac1d5bea7d7f1ad0f033 diff --git a/version-control/git/git-and-github/instructor_notes.md b/version-control/git/git-and-github/instructor_notes.md new file mode 100644 index 0000000..d59c0d4 --- /dev/null +++ b/version-control/git/git-and-github/instructor_notes.md @@ -0,0 +1,247 @@ +# git/GitHub + +The goal of this lesson is to introduce the students to [git][] via +collaboration on [GitHub][]. + +## Introduction + +- Say some introductory stuff about version control in general, and git/GitHub + in particular. + +*Note: The figures in the [Visual Git Reference][visual git] can be a good +stand-in if you have nowhere to draw.* + +## Setup and Signup + +- Have everyone configure git: + + $ git config --global user.name "User Name" + $ git config --global user.email "user@email.com" + $ git config --global core.editor "nano" + $ git config --global color.ui "auto" + +- Give a little tour of [GitHub][]. +- Have everyone make [GitHub][] accounts. + +### Make and Clone + +- Make a new demo repo on [GitHub][] explaining the process as you go + (probably on your personal account). + - Have [GitHub][] put in a README so it can be cloned. +- Explain that much like a browser navigates to websites using a URL, git talks + to remote repositories using a URL. +- Explain the different URL options: + - Read/write `ssh` protocol requires [ssh keys][], which make it so you + don't have to enter username/password. + - `https` protocol takes username/password. + - `git` protocol is read-only. +- Now we want to get a copy of this down on all of our computers -- `git clone`! + - Have everyone do this via the `https` URL. +- `ls` to show the new directory and `cd` into it. +- Compare the local listing to what you see on [GitHub][]. Same for now, but + not for long! + +## Basics + +### Local Basics + +**IMPORTANT:** Make sure you tell people *not* to make their own local changes, +that will make things really complicated later when people pull. Alternatively, +you can go ahead and let them do whatever they like and use it as a teaching +moment on `git reset --hard` in a few minutes when it's time to start the +collaboration. + +- On the white board draw a box representing the working area and explain that + this is where you work and make changes. +- Make a new file called `top-things-to-learn.md` and put the title + "Top Things We Want to Learn" in it. +- `git status` -- highlight the "Untracked files" section and that git tells + you how to add a file to the next commit. + +### Composing the Snapshot + +- On the white board draw a box representing the staging area (index) and + explain that this is where we set up the next snapshot of our project. + - Like a photographer in a studio, we're putting together a shot before + we actually snap the picture. + - Connect the working area box and the staging box with `git add`. +- Run `git add top-things-to-learn.md`. +- `git status` -- highlight the "Changes to be committed" section + and git telling you how to unstage the new file. + +### Taking the Snapshot + +- On the white board draw a box representing the project history. Once we take + a snapshot of the project that snapshot becomes a permanent reference point + in the project's history that we can always go back to. + - The history is like a photo album of changes, and each snapshot has a + time stamp, the name of the photographer, and a description. + - Connect the staging area to the history with `git commit`. +- Run `git commit` and explain log messages. + - Summary message at the top, longer one below. +- `git status` -- nothing going on! + +### Looking at the History + +- `git log` -- Shows description of what we've done. + - `git log --oneline` -- Abbreviated version. +- Explain the commit hash. + - Unique identifier of that commit if we ever want to refer to it. + - Comes from "hashing" stuff associated with the commit, like the changes + we made. + - Can demo hashing with Python's `hashlib.sha1`. + +### Previewing Changes + +- The file we're making is going to be a list of the top things everyone wants + to learn in the boot camp. Add your item (e.g. everyone's names) and save. +- `git status` -- point out that now we have a modified file instead of an + untracked file, but the procedure for adding it to the next snapshot is + the same. +- Want to see the changes you're about to add? `git diff`! +- `git add` +- `git diff` -- now it doesn't show anything. `git diff` shows differences + between the working area and the staging area. + - To see differences between the staging area and the most recent commit + use `git diff --cached`. +- `git commit -m` -- This time use the `-m` option and show that for short + commit messages you can just enter them at the command line. + +### Undoing Changes + +- Say I want to redo the previous commit... +- `git log --oneline` -- grab the commit has for the point we want to go back to. +- `git reset COMMIT` +- `git log --oneline` -- highlight that the latest commit is gone +- `git status` -- But the changes haven't gone anywhere. +- I can now edit the file to fix whatever was wrong and re-commit. + +## Sharing + +- Now I want to share my changes with everyone so they can start working on + it too. + +### Remotes + +- As we said back at the beginning, git uses URLs to point repositories on other + computers, in this case [GitHub's][GitHub] servers. +- We can give these remote repositories names so that we don't have to type + in the full URL all the time, and in fact git has already set one up for us. +- `git remote` -- there's a remote called "origin". +- `git remote -v` -- we can see that it points to the same URL we cloned from, + git sets this up automatically. + +### Branches + +- On the [GitHub][] view of the repo highlight the branches pull-down -- right + now it only has one branch called "master", this is another thing git makes + for us by default. +- What branch are we on locally? `git branch`. +- Give a short explanation of branches and mention that we will come back to + them later. + - Isolated development environments. +- When git communicates with a remote repository it needs to know what branch + is changing, in this case we'll just stick with "master". + +### Pushing + +- Use `push` command to send data to a remote repository, and we also have to + specify the remote name and branch name: `git push origin master`. +- Refresh the [GitHub][] view. + +### Pulling + +**IMPORTANT:** If students have been making local commits, this is the time at +which they will need to use `git reset --hard` to get back in sync with you. + +- `pull` is the reciprocal command, must specify remote and branch. +- Have everyone `git pull origin master`. + +### Collaborate + +- Pick a student to add their top thing to learn to the list: + - Add them to the collaborator list on the demo repo. + - edit, save, `add`, `commit`, `push` +- Have everyone `pull`. + +### Rebase + +#### No Conflict + +- Have another student add their thing and push. +- Make a change to the README file before pulling. +- Try to push. +- On the white board draw the situation: my repo and the remote repo have + different development histories and git doesn't know how to pull things + together. +- It would be nice if I could move my local change after the remote change. + (Draw picture.) There's a command for that! +- `git fetch origin` -- This gets information from the remote repository + but doesn't integrate it with your local repo like `pull` does. +- `git rebase origin/master` -- `origin/master` is how we specify the fetched + data for the remote named "origin" and it's branch named "master". + - This replays my local changes on top of the state of the remote repo. +- `git log --oneline` -- Now my change is after the remote change. +- `git push origin master` +- Have everyone pull. + +#### With Conflicts + +- Again, have a student add their thing and push. +- Before pulling make a change in the same place in the same file. +- Try to rebase as above. +- Explain the conflict message git prints out. +- Show the conflict messages in the file and how to clean it up. +- Continue the rebase and push the result. +- Have everyone pull. + +## Developing in Branches + +Often you want to leave a stable version of your code alone while you make some +potentially disruptive changes. Or you and someone else are working on the code +and you want to be able to work without worrying what others are doing. + +- It's going to take a long time to get everyone's top thing to learn onto the + list one at a time, so the room is going to break out into groups and each + come up with their own list. +- So that they can all do this and then push their result to [GitHub][] each + is going to work in their own, isolated branch. + +### Making a New Branch + +*Note: The [Learn Git Branching][] app can be a useful way to +illustrate this part of the lesson.* + +- Make a new branch: `git branch matt-list`. +- `git branch` -- highlight the asterisk showing the branch we're currently on. +- Move to that branch: `git checkout matt-list`. +- `git branch` -- asterisk moved! +- Make a change and push. + - **IMPORTANT:** have to specify new branch named when pushing, not "master". +- `git checkout master` -- show that your change is *not* in master. +- Show how to browse to the other branch on [GitHub][]. +- Have each group pick a unique branch name, switch to that branch, and add + all of their top things to learn to the list and push the result. + +### Resolving the Changes + +- Browse all of the new branches on [GitHub][]. +- Illustrate the situation on the [Learn Git Branching][] app. +- Could just pick one of these branches as the new one "master" and move on, + but we're more adventurous than that. +- Make sure you're in "master". +- `git fetch origin` -- without a branch name it grabs all of the new branches. +- Pick a branch and `git merge branch-name`. + - Should be a smooth fast-forward. + - Illustrate on the [Learn Git Branching][] app. +- Pick another branch and try to merge. + - Resolve conflicts, add, and commit. + - Illustrate on the [Learn Git Branching][] app. +- Repeat as necessary. +- Push the final result to [GitHub][]. + +[git]: http://git-scm.com/ +[GitHub]: http://github.com +[ssh keys]: https://help.github.com/articles/generating-ssh-keys +[visual git]: http://marklodato.github.com/visual-git-guide/index-en.html +[Learn Git Branching]: http://pcottle.github.com/learnGitBranching/?NODEMO