Google released the Android L developer preview factory images for the Nexus 5 and Nexus 7 (2013) yesterday, and people who installed them quickly noticed that root access was no longer available. Thankfully, it seems rooting Android L isn’t as difficult as some might have thought, with a fix detailed by SuperSU developer Chainfire.
It turns out that getting root access on Android L is as simple as moving a system file from one folder to another, and a modified SuperSU package has been made available online. As always, you will need to flash the SuperSU file from a custom recovery and reboot, after which you will get full low-level access on your Nexus 5 or Nexus 7 (2013) running the developer preview.
You can use our handy guide for rooting the Nexus 5 for reference, and download the modified SuperSU file here.