Git and GitHub, with a side of Microsoft

2018-06-05T17:44:16Z

If you develop software and haven't just returned from the moon, you've undoubtedly heard that GitHub is being acquired by Microsoft. Depending on your affiliations you might be spelling "being acquired by" as "selling out to". The rest of you are probably wondering what on Earth a GitHub is, and why Microsoft would want one. Let me explain.

Please note: this post isn't about my opinion of today's news. It's really too early to tell, though I may get into that a little toward the end. Instead, I'm going to explain what GitHub is, and why it matters. But first I have to explain Git.

Git is a version-control system. (Version-control systems are sometimes called "source code management" (SCM) systems. If you look closely you might even have spotted "scm" in git's URL up there at the end of the last paragraph.) Basically, a version-control system lets you record the complete history of a project, with what changes were made, who made the each change, when they changed it, and their notes about what they did and why. It doesn't have to be a software project, either. It can be recipes, photographs, books, the papers you're writing for school, or even blog entries. (Yes, I do.)

Before git, most version-control systems kept track of changes in text files (which of course is what all source code is) by recording which lines are different from the previous version. (It's usually done by a program called diff.) This was very compact, but it could also be very slow if you had to undo all the changes between two versions in order to see what the older one looked like.

Git, on the other hand, is blindingly fast in part because it works in the stupidest way possible (which is why it's called "git"). It simply takes the new version of each file that changed since the last version, zips it up, and stuffs it whole into its repository. So it takes git about the same amount of time to roll a file back two versions or two hundred.

The other thing that makes git fast is where it keeps all of its version information. Before git, most version-control systems used a centralized repository on a server somewhere. (Subversion, one of the best of these, even lets you browse the repository with a web browser.) That means that all the change information is going over a network. Git keeps its repository (these days everyone shortens that to "repo") on your local disk, right next to your working copy, in a hidden subdirectory called ".git".

Because its repo is local, and contains the entire history of your project, you don't need a network connection to use git. On the beach, in an airplane, on a boat, ~~with a goat~~, it doesn't matter to git. It's de-centralized. It gets a little more complicated when more than one developer is working on a project.

Bob's been in the office all week working on a project. When his boss, Alice, comes back from the open source conference she's been at all week, all she has to do is tell git to fetch all the changes that Bob made while she was away. Git gets them directly from Bob's repo. If Alice didn't make any changes, that's called a "fast-forward" merge -- git just takes the changes that Bob made, copies those files into Alice's repo, updates her working tree, and it's done.

It's a little trickier if Alice had time to make some changes, too. Now Alice has to merge the two sets of changes, and then let Bob pull the merged files onto his computer. By the way, a "pull" is just a fetch followed by a merge, but it's so common that git has a shorthand way of doing it. (I'm oversimplifying here, but this isn't the time to go into the difference between merge and rebase. It's also not a good time to talk about branches -- maybe some other week.) As you can imagine, this gets out of hand pretty quickly, and it's even worse if there's a whole team working on the project.

The obvious thing to do is for the group to have one repo on a server somewhere that has what everyone agrees is the definitive set of files on it. Bob pushes his changes to the server, and when Alice tries to push her changes, git balks and gives her an error message. Now it's Alice's responsibility to make any necessary fixes and push them to the server. Actually, in a real team, Alice would send her proposed changes around by making a diff and sending email to the other team members to review, and not actually push her changes until someone approves them.

In a large team, this is kind of a hub-and-spokes arrangement. You can see where this is going, right?

GitHub is a company that provides a place for people and projects to put shared git repositories where other people can see them, clone them, and contribute to them. GitHub has become wildly popular, because it's a great place to share software. If you have an open-source software project, putting a public repo on GitHub is the most effective way to reach developers. It's so popular that Google and Microsoft shut down their own code-hosting sites (Google Code and CodePlex respectively) and moved to GitHub. Microsoft, it turns out, is GitHub's biggest contributor.

Putting a public repository on GitHub is free. If you want to set up private repositories, GitHub will charge you for it, and if your company wants to put a clone of GitHub on its own private servers they can buy GitHub Enterprise, but if your software is free, so's your space on GitHub.

That's a bit of a problem, because the software that runs GitHub is not free. That means that they need a steady stream of income to pay their in-house developers, because they're not going to get any help from the open-source developer community. GitHub lost $66 million in 2016, and doesn't really have a sustainable business model that would make them attractive to investors. They needed to get acquired, or they had a real risk of going under. And when a service based on proprietary software goes under, all of their customers have a big problem. But their users? Heh.

Everybody knows the old adage, "if you're getting a service for free you're not the customer, you're the product." That's especially true for companies like Google and Facebook, which sell their users' eyeballs to advertisers. It's a lot less true for a company whose users can leave any time they want, painlessly, taking all their data and their readers with them. I'm sure most of my readers here on Dreamwidth remember what happened to Livejournal when they got bought by the Russians. Well, GitHub is being bought by Microsoft. It's not entirely clear which is worse.

GitHub has an even worse problem than Livejournal did, because "cross-posting" is basically the way git works. There's a company called GitLab that looks a lot like GitHub, except that their core software -- the stuff that wraps a slick web interface around a git repository -- is open source. (They do sell extensions, but most projects aren't going to need them.) If you want to set up your own private GitLab site, it's free, and you can do it in ten minutes with a one-line command. If you find bugs, you can fix them yourself. You'll find a couple of great quotes from their blog at the end of the notes, but the bottom line is that 100,000 repositories have moved from GitHub to GitLab in the last 24 hours.

And once you've moved a project to GitLab, you don't have to worry about what happens to it, because the open-source core of it will continue to be maintained by its community. That's what happened when a company called Netscape went belly-up: Mozilla Firefox is still around and doing fine. And if the fact that GitLab is for profit is a problem for you, there's Apache Allura, gitolite3, gitbucket, and gitweb (to name a few). Go for it!

This so wasn't what I was planning to write today.

Notes:
@ Microsoft Reportedly Acquires GitHub | Linux Journal
The article ends with a list of alternatives:
Gitea
Apache Allura
GitBucket: A Git platform
GitLab
@ Microsoft acquires GitHub for $7.5 billion - TFiR
" According to reports, GitHub lost over $66 millions in 2016. At the same time
GitLab, a fully open source and decentralized service is gaining momentum, giving
users a fully open source alternative. "
@ Microsoft to acquire GitHub for $7.5 billion | Stories official press release
@ Microsoft + GitHub = Empowering Developers - The Official Microsoft Blog
@ A bright future for GitHub | The GitHub Blog
@ Congratulations GitHub on the acquisition by Microsoft | GitLab
" While we admire what's been done, our strategy differs in two key areas. First,
instead of integrating multiple tools together, we believe a single application,
built from the ground up to support the entire DevOps lifecycle is a better
experience leading to a faster cycle time. Second, it’s important to us that the
core of our product always remain open source itself as well. "
@ GitLab Ultimate and Gold now free for education and open source | GitLab
" It has been a crazy 24 hours for GitLab. More than 2,000 people tweeted about
#movingtogitlab. We imported over 100,000 repositories, and we've seen a 7x increase
in orders. We went live on Bloomberg TV. And on top of that, Apple announced an
Xcode integration with GitLab. "

Another fine post from The Computer Curmudgeon.

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Git and GitHub, with a side of Microsoft