simple-email/node_modules/env-ci/services/circleci.js

// https://circleci.com/docs/2.0/env-vars/#built-in-environment-variables

const {prNumber} = require('../lib/utils');

module.exports = {
	detect({env}) {
		return Boolean(env.CIRCLECI);
	},
	configuration({env}) {
		const pr = env.CIRCLE_PR_NUMBER || prNumber(env.CIRCLE_PULL_REQUEST || env.CI_PULL_REQUEST);
		const isPr = Boolean(pr);

		return {
			name: 'CircleCI',
			service: 'circleci',
			build: env.CIRCLE_BUILD_NUM,
			buildUrl: env.CIRCLE_BUILD_URL,
			job: `${env.CIRCLE_BUILD_NUM}.${env.CIRCLE_NODE_INDEX}`,
			commit: env.CIRCLE_SHA1,
			tag: env.CIRCLE_TAG,
			branch: isPr ? undefined : env.CIRCLE_BRANCH,
			pr,
			isPr,
			prBranch: isPr ? env.CIRCLE_BRANCH : undefined,
			slug: `${env.CIRCLE_PROJECT_USERNAME}/${env.CIRCLE_PROJECT_REPONAME}`,
		};
	},
};