Change Nx Default Affected Branch to Main

The Nx affected commands are a powerful way to scale monorepos by only rebuilding and retested the apps and libraries that could be affected by a particular change. This is accomplished by comparing hashes of the files modified in the current branch compared to the base branch which defaults to master. It's easy to pass in a different branch as a parameter with --base, however, you can also change this default in the workspace nx.json.

First, make sure that you have created the new base branch. In this example, we will be using main as our base branch.

Next, edit the workspace nx.json. If you do not have the affected property then you will need to add that first, and then you can customize the base branch.

{
  "npmScope": "nxtend",
  "affected": {
    "defaultBase": "main"
  },
  ...
}

Lastly, this feature is only available in Nx 9.5 or higher. If you are currently on a version of Nx lower than this then I recommend upgrading to the latest version of Nx, or at least the latest version of Nx 9.

Upgrade to latest version:

nx migrate latest

Upgrade to Nx 9.7:

nx migrate @nrwl/workspace@9.7.0