now-flow/src/resolvers/github.js

Add deployment workflows to Zeit now

//@flow
const { tmpdir } = require('os')
const { parse, format } = require('url')
const fetch = require('node-fetch')
const tar = require('tar-fs')
const pipeStreams = require('pipe-streams-to-promise')
const { mkdir } = require('fs-extra')
const uid = require('uid-promise')
const { createGunzip } = require('zlib')
const { join } = require('path')
const debug = require('debug')('now:resolvers:github')

// matches a parameter that can be `now`d like zeit/now-cli#master
const DEPLOY_PARAM_REGEX = /^([\w-]+)\/([\w-]+)(#\w+)?$/

// matches whether the parameter could be a github url
const GITHUB_TEST_REGEX = /^(https?:\/\/)(www\.)?github\.com/

// matches a github url pathname like: zeit/now-cli/tree/master
const URL_PATHNAME_REGEX = /^\/([\w-]+)\/([\w-]+)(\/tree\/(\w+))?$/

const resolveGitHub = (param) => {
	// support simple `user/repo` syntax
	const match = param.match(DEPLOY_PARAM_REGEX)
	if (match) {
		const [, user, repo, tree = 'master'] = match
		return resolveGitHubByURL(`https://github.com/${user}/${repo}/tree/${tree}`)
	} else if (GITHUB_TEST_REGEX.test(param)) {
		return resolveGitHubByURL(param)
	} else {
		return null
	}
}

const resolveGitHubByURL = async (url) => {
	debug('resolving %s by github url', url)
	if (/^https?/.test(url)) {
		const parsed = parse(url)
		if (parsed.hostname === 'github.com') {
			const httpsUrl =
        'https:' === parsed.protocol ? url : format(Object.assign({}, parsed))
			const res = await fetch(httpsUrl)
			if (res.ok) {
				debug('attempting github clone')
				const { pathname = '' } = parsed
				const match = pathname.match(URL_PATHNAME_REGEX)
				if (match) {
					const [, user, repo, , tree] = match
					const downloadURL = format({
						protocol: 'https:',
						hostname: 'codeload.github.com',
						pathname: `/${user}/${repo}/tar.gz/${tree}`
					})
					debug('fetching download url', downloadURL)
					const downloadRes = await fetch(downloadURL, { compress: false })
					if (downloadRes.ok) {
						const tmpDir = join(tmpdir(), `now-gh-${await uid(20)}`)
						debug('creating tmp dir to extract', tmpDir)
						try {
							await mkdir(tmpDir)
						} catch (err) {
							throw new Error(
								'Error occurred while trying to extract ' +
                  `GH tarball to tmp directory ${tmpDir}: ${err.stack}`
							)
						}
						debug('unzipping and untarring stream')
						await pipeStreams([
							downloadRes.body,
							createGunzip(),
							tar.extract(tmpDir)
						])
						// instead of stripping a directory upon untar,
						// we return the full path to the extracted project,
						// so that now can take advantage of the name
						return join(tmpDir, `${repo}-${tree}`)
					} else {
						throw new Error(
							'An HTTP error ${res.status} was returned ' +
                `by "${downloadURL}"`
						)
					}
				} else {
					debug('invalid github project url')
					return null
				}
			} else {
				debug('non-200 from github (%d)', res.status)
				return null
			}
		} else {
			debug('skipping non-github hostname')
			return null
		}
	} else {
		return null
	}
}

module.exports = resolveGitHub