branchMover: A Shiny app for moving the default branch of your GitHub repos

By Garrick Aden-Buie in Blog

November 2, 2021

Posted on:
November 2, 2021
Length:
4 minute read, 827 words
Categories:
Blog
Tags:
R usethis GitHub git Apps Shiny RStudio
Source:
content/blog/2021/branchmover/index.Rmarkdown
See Also:
Pull Request Flow with usethis
Signed and verified: signed git commits with Keybase and RStudio
Create a GitHub issue from a reprex with shrtcts
The 'Branch Mover' shiny app on the main 'Repos' screen, showing an interactive table of repositories associated with a GitHub user. The table shows the default branch, language of the repo, number of forks and stars, and a button that can be clicked to initiate moving the repo's default branch.

Branch Mover

Introducing branchMover, a Shiny app slash RStudio addin for coordinated default branch changes across your GitHub repositories.

The app show you the default branch name for all of your repos and coordinates changing the default branch, including creating an issue to communicate the change.

Moving to main street #

Over the past year, there’s been a concerted effort among people who create and manage git repositories to move away from the default branch name of master to something more intentional: typically main.

RStudio and the tidyverse team recently undertook the giant challenge of changing the default branch of RStudio’s approximately 350 public repositories (most of which are all open source!). Jenny Bryan wrote about the branch-changing experience on the tidyverse blog.

Watching Jennys’s superb stewardship of the change inspired a new app branchMover. Or is it named Branch Mover? Admittedly, I didn’t spend much time thinking about the name because the app won’t be in your life for very long.

The goal of branchMover is to help you coordinate a default branch change across the repos you maintain. The app shows you all of the repos associated with your GitHub account and their current default branch. Because you might want to start with your less popular repos, you can sort by number of forks and stars on each repo.

There’s also a button to change the default branch. When you click the button, the app clones your repo and uses the usethis package and the recently added usethis::git_default_branch_rename() function to update the default branch of your repo.

I followed Jenny’s lead and the app will create an issue announcing the change. If all goes well, the issue is closed a few seconds later with instructions for your users on how to update any local copies of your repo. If it doesn’t go well, the issue stay open as a reminder to you to finish the process.

Unfortunately, branchMover doesn’t update the default branch in your local copies of your repos. Thankfully, this is relatively pain-free with the usethis::git_default_branch_rediscover() function, added in usethis version 2.1.2.

The next time you find yourself in your local copy of your repo, run git_default_branch_rediscover() to reconfigure your branch situation.

git_default_branch_rediscover()
#> ℹ Default branch of the source repo 'jennybc/happy-git-with-r': 'main'
#> ✓ Default branch of local repo has moved: 'master' --> 'main'

Installation #

You can install branchMover from GitHub with:

# install.packages("devtools")
devtools::install_github("gadenbuie/branchMover")

The app uses the usethis and gh packages. You need to configure gh with a Personal Access Token to be able to authenticate with the GitHub API. Read more about setting up a PAT in one of these places:

Then, in RStudio, run the app with:

branchMover::app()

If you’d like to explore or reconfigure the default branch of repositories that you manage in other organizations, provide app() with the user or organization name. Branch Mover will tell you how many repos you have access to in the organization and it won’t let you update branch names for repos where you don’t have admin permissions.

branchMover::app("rstudio-education")
#> ℹ @rstudio-education has 57 total repositories (including forks)
#> • 57 public repos
#> • 0 private repos
#> ℹ 57 non-fork repositories have the following default branches:
#> x master: 51 repos
#> ✓ main: 6 repos
#> ℹ You have admin rights on 1 repo

Why change branches? #

If you want to learn more about how git’s default branch works and why many are opting to choose a more intentional default, I highly recommend Jenny’s detailed article Renaming the default branch, which I’ll quote directly:

Technically, Git has no official concept of the default branch. But in practice, most Git repos have an effective default branch. If there’s only one branch, this is it! It is the branch that most bug fixes and features get merged in to. It is the branch you see when you first visit a repo on a site such as GitHub. On a Git remote, it is the branch that HEAD points to. The default branch may not be precisely defined in Git itself, but most of us know it when we see it.

Historically, master has been the most common name for the default branch, but main is an increasingly popular choice. There is coordinated change across the Git ecosystem that is making it easier for users to make this switch, for example:

Jenny Bryan, Renaming the default branch


Branch Mover was built by Garrick Aden-Buie. Come say hi to me on Twitter at @grrrck.