Custom plugin for filtering builds on Netlify by doppler environment

doppler-build-hook

/**
 * When environemnt variables are updated in Doppler, Doppler posts a deploy webhook (created in Netlify).
 * Doppler uses the same webhook for updates to all environments (prd, stg, dev). Since the webhook is setup
 * for deploying to the master/main branch, we want to ignore requests from all environments except for 'prd'
 *
 * Doppler Reference: https://docs.doppler.com/docs/enclave-webhooks
 * Netlify Reference: https://docs.netlify.com/configure-builds/build-plugins/create-plugins
 *
 * @param {string} [inputs.title] - Title of the build hook used by Doppler.  Assumes webhook name
 * of "Doppler" if not provided
 */

const PAYLOAD_INITIAL = {
  config: {},
  project: {},
  workplace: {}
};

module.exports = function dopplerWebhookDeployments(inputs) {
  const {
    INCOMING_HOOK_TITLE,
    INCOMING_HOOK_BODY = PAYLOAD_INITIAL,
    INCOMING_HOOK_URL,
    CONTEXT
  } = process.env;

  const webhookName = (inputs && inputs.title) || 'Doppler';

  const dopplerBuildHook = INCOMING_HOOK_TITLE === webhookName;
  const dopperEnvUpdate = INCOMING_HOOK_BODY.config.environment;
  const prodEnvUpdate = dopperEnvUpdate === 'prd';

  if (dopplerBuildHook) {
    return {
      onPreBuild: ({ utils }) => {
        console.log('Incoming Doppler build request', {
          INCOMING_HOOK_TITLE,
          INCOMING_HOOK_URL,
          INCOMING_HOOK_BODY,
          CONTEXT
        });

        if (!prodEnvUpdate) {
          utils.build.cancelBuild(
            `Doppler build hook for ${dopperEnvUpdate}. Only production updates trigger deployments on master.`
          );
        }
      }
    };
  }

  // If deploy is not triggered by doppler then no need to run onPreBuild hook.
  return {};
};