Engineering

At GitHub we use MySQL as our main datastore. While repository data lies in git, metadata is stored in MySQL. This includes Issues, Pull Requests, Comments etc. We also auth…

GitHub hosts a wide range of user content, and like all large websites this often causes us to become a target of denial of service attacks. Around a year ago,…

We shipped subresource integrity a few months back to reduce the risk of a compromised CDN serving malicious JavaScript. That is a big win, but does not address related content…

Edit: DGit is now called Spokes GitHub hosts over 35 million repositories and over 30 million Gists on hundreds of servers. Over the past year, we’ve built DGit, a new…

GitHub.com no longer delivers its icons via icon font. Instead, we’ve replaced all the Octicons throughout our codebase with SVG alternatives. While the changes are mostly under-the-hood, you’ll immediately feel…

Anyone who has worked on a large enough codebase knows that technical debt is an inescapable reality: The more rapidly an application grows in size and complexity, the more technical…

At GitHub we place an emphasis on stability, availability, and performance. A large component of ensuring we excel in these areas is deploying services on bare-metal hardware. This allows us…

Looking through our exception tracker the other day, I ran across a notice from our slow-query logger that caught my eye. I saw a SELECT … WHERE … LIKE query…

At GitHub we have a lot of software running our product and company. We also have a lot of potential contributing members. Being able to get from git clone to…

At GitHub, we use a variant of the Flow pattern to deploy changes: new code is always deployed from a pull request branch, and merged only once it has been…

Earlier this spring, we upgraded our database cluster to MySQL 5.6. Along with many other improvements, 5.6 added some exciting new features to the performance schema. MySQL’s performance schema is…

Believe it or not, just over a year ago, GitHub Pages, the documentation hosting service that powers nearly three-quarters of a million sites, was little more than a 100-line shell…

Providing well-written documentation helps people understand, make use of, and contribute back to your project, but it’s only half of the documentation equation. The underlying system used to serve documentation…

Last Friday we announced and performed a migration of all GitHub Pages to their own github.io domain. This was a long-planned migration, with the specific goal of mitigating phishing attacks…

Over the last month or so, we noticed steady week-over-week rises in overall MySQL query time. A poorly-performing database makes for a slow site and a slow site makes for…