Publishing

We’re still in our working directory:

import os

top_dir = os.getcwd()
git_dir = os.path.join(top_dir, "learning_git")
working_dir = os.path.join(git_dir, "git_example")
os.chdir(working_dir)
working_dir
'/home/runner/work/rse-course/rse-course/module04_version_control_with_git/learning_git/git_example'

Sharing your work

So far, all our work has been on our own computer. But a big part of the point of version control is keeping your work safe, on remote servers. Another part is making it easy to share your work with the world In this example, we’ll be using the GitHub cloud repository to store and publish our work.

If you have not done so already, you should create an account on GitHub: go to https://github.com/, fill in a username and password, and click on “sign up for free”.

Creating a repository

Ok, let’s create a repository to store our work. Hit “new repository” on the right of the github home screen, or click here.

Fill in a short name, and a description. Choose a “public” repository. Don’t choose to add a Readme.

Paying for GitHub

For this course, you should use public repositories in your personal account for your example work: it’s good to share! GitHub is free for open source, but in general, charges a fee if you want to keep your work private.

In the future, you might want to keep your work on GitHub private.

Students can get free private repositories on GitHub, by going to GitHub Education and filling in a form (look for the Student Developer Pack).

Adding a new remote to your repository

Instructions will appear, once you’ve created the repository, as to how to add this new “remote” server to your repository. In this example we are using pre-authorised Deploy Keys to connect using the SSH method. If you prefer to use username and password/token, these instructions will be slightly different:

%%bash
git remote add origin git@github.com:alan-turing-institute/github-example.git

Note that the https version of this instruction would be something like git remote add origin https://${YOUR_USERNAME}:${GITHUB_TOKEN}@github.com/alan-turing-institute/github-example.git

%%bash
git remote -v
origin	git@github.com:alan-turing-institute/github-example.git (fetch)
origin	git@github.com:alan-turing-institute/github-example.git (push)
%%bash
git push -uf origin main # Note we use the '-f' flag here to force an update
Warning: Permanently added the ECDSA host key for IP address '140.82.114.3' to the list of known hosts.
To github.com:alan-turing-institute/github-example.git
 + fd7d7c2...fa4dd70 main -> main (forced update)
branch 'main' set up to track 'origin/main'.

Remotes

The first command sets up the server as a new remote, called origin.

Git, unlike some earlier version control systems is a “distributed” version control system, which means you can work with multiple remote servers.

Usually, commands that work with remotes allow you to specify the remote to use, but assume the origin remote if you don’t.

Here, git push will push your whole history onto the server, and now you’ll be able to see it on the internet! Refresh your web browser where the instructions were, and you’ll see your repository!

Let’s add these commands to our diagram:

message = """
Working Directory -> Staging Area : git add
Staging Area -> Local Repository : git commit
Working Directory -> Local Repository : git commit -a
Local Repository -> Working Directory : git checkout
Local Repository -> Staging Area : git reset
Local Repository -> Working Directory: git reset --hard
Local Repository -> Remote Repository : git push
"""
from wsd import wsd

%matplotlib inline
wsd(message)
../_images/04_03_publishing_14_0.png

Playing with GitHub

Take a few moments to click around and work your way through the GitHub interface. Try clicking on ‘test.md’ to see the content of the file: notice how the markdown renders prettily.

Click on “commits” near the top of the screen, to see all the changes you’ve made. Click on the commit number next to the right of a change, to see what changes it includes: removals are shown in red, and additions in green.

Working with multiple files

Some new content

So far, we’ve only worked with one file. Let’s add another:

vim lakeland.md
%%writefile lakeland.md
Lakeland  
========   
  
Cumbria has some pretty hills, and lakes too.  
Writing lakeland.md
cat lakeland.md
Lakeland  
========   
  
Cumbria has some pretty hills, and lakes too.  

Git will not by default commit your new file

%%bash
git commit -am "Try to add Lakeland" || echo "Commit failed"
On branch main
Your branch is up to date with 'origin/main'.

Untracked files:
  (use "git add <file>..." to include in what will be committed)
	__pycache__/
	lakeland.md
	wsd.py

nothing added to commit but untracked files present (use "git add" to track)
Commit failed

This failed, because we’ve not told git to track the new file yet.

Tell git about the new file

%%bash
git add lakeland.md
git commit -am "Add lakeland"
[main d9160c8] Add lakeland
 1 file changed, 4 insertions(+)
 create mode 100644 lakeland.md

Ok, now we have added the change about Cumbria to the file. Let’s publish it to the origin repository.

%%bash
git push
To github.com:alan-turing-institute/github-example.git
   fa4dd70..d9160c8  main -> main

Visit GitHub, and notice this change is on your repository on the server. We could have said git push origin to specify the remote to use, but origin is the default.

Changing two files at once

What if we change both files?

%%writefile lakeland.md
Lakeland  
========   
  
Cumbria has some pretty hills, and lakes too

Mountains:
* Helvellyn
Overwriting lakeland.md
%%writefile test.md
Mountains and Lakes in the UK   
===================   
Engerland is not very mountainous.
But has some tall hills, and maybe a
mountain or two depending on your definition.
Overwriting test.md
%%bash
git status
On branch main
Your branch is up to date with 'origin/main'.

Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git restore <file>..." to discard changes in working directory)
	modified:   lakeland.md
	modified:   test.md

Untracked files:
  (use "git add <file>..." to include in what will be committed)
	__pycache__/
	wsd.py

no changes added to commit (use "git add" and/or "git commit -a")

These changes should really be separate commits. We can do this with careful use of git add, to stage first one commit, then the other.

%%bash
git add test.md
git commit -m "Include lakes in the scope"
[main e8c018d] Include lakes in the scope
 1 file changed, 4 insertions(+), 3 deletions(-)

Because we “staged” only test.md, the changes to lakeland.md were not included in that commit.

%%bash
git commit -am "Add Helvellyn"
[main 2e2ee6e] Add Helvellyn
 1 file changed, 4 insertions(+), 1 deletion(-)
%%bash
git log --oneline
2e2ee6e Add Helvellyn
e8c018d Include lakes in the scope
d9160c8 Add lakeland
fa4dd70 Revert "Add a lie about a mountain"
366e9c0 Change title
0c51bea Add a lie about a mountain
d833c8a First commit of discourse on UK topography
%%bash
git push
To github.com:alan-turing-institute/github-example.git
   d9160c8..2e2ee6e  main -> main
message = """
participant "Jim's remote" as M
participant "Jim's repo" as R
participant "Jim's index" as I
participant Jim as J

note right of J: vim test.md
note right of J: vim lakeland.md

note right of J: git add test.md
J->I: Add *only* the changes to test.md to the staging area

note right of J: git commit -m "Include lakes"
I->R: Make a commit from currently staged changes: test.md only

note right of J: git commit -am "Add Helvellyn"
J->I: Stage *all remaining* changes, (lakeland.md)
I->R: Make a commit from currently staged changes

note right of J: git push
R->M: Transfer commits to Github
"""
wsd(message)
../_images/04_03_publishing_40_0.png