on-circle provides a set of utility for configuring and running scripts on CircleCI. You can use it locally, to automate the scaffolding of your project, or remotely, to simplify some of the most common tasks (push back to a repo, release on npm, etc).
# Add the current project to CircleCI
yarn run oncircle add
# Set an ENV variable
yarn run oncircle setenv API_KEY=4815162342
// Run this from a job running on CircleCI
const onCircle = require('on-circle');
await onCircle.run(
  async (success, failure, gitChangedFiles, gitCommitAll, gitPush }) => {
    // Run any custom code here, for example calling
    // external APIs to update some data.
    // You can even update the repo and push back
    // using the gitCommitAll() and gitPush() methods

    if (everythingIsOk) {
      return success('Everything worked');
    } else {
      return failure('Something is broken');

    // Oh, and any error will be caught and transformed
    // into a GitHub issue