feat: ping teams based on which files were changed

Using .github/CODEOWNERS, `github-bot` will ping the appropriate teams
based on which files were changed in a Pull Request. This feature is
inteded to work around GitHub's limitation which prevents teams without
explicit write access from being added as reviewers (thus preventing the
vast majority of teams in the org from being used on GitHub's CODEOWNERS
feature).

Ref: nodejs/node#33984

lib/logger.js

@@ -4,7 +4,7 @@ const path = require('path')
 const bunyan = require('bunyan')
 
 const isRunningTests = process.env.npm_lifecycle_event === 'test'
-const stdoutLevel = isRunningTests ? 'FATAL' : 'INFO'
+const stdoutLevel = isRunningTests ? 'FATAL' : process.env.LOG_LEVEL || 'INFO'
 
 const daysToKeepLogs = process.env.KEEP_LOGS || 10
 const logsDir = process.env.LOGS_DIR || ''

lib/node-owners.js

@@ -0,0 +1,31 @@
+'use static'
+
+const { parse } = require('codeowners-utils')
+// NOTE(mmarchini): `codeowners-utils` doesn't respect ./ prefix,
+// so we use micromatch
+const micromatch = require('micromatch')
+
+class Owners {
+  constructor (ownersDefinitions) {
+    this._ownersDefinitions = ownersDefinitions
+  }
+
+  static fromFile (content) {
+    return new Owners(parse(content))
+  }
+
+  getOwnersForPaths (paths) {
+    let ownersForPath = []
+    for (const { pattern, owners } of this._ownersDefinitions) {
+      if (micromatch(paths, pattern).length > 0) {
+        ownersForPath = ownersForPath.concat(owners)
+      }
+    }
+    // Remove duplicates before returning
+    return ownersForPath.filter((v, i) => ownersForPath.indexOf(v) === i).sort()
+  }
+}
+
+module.exports = {
+  Owners
+}

lib/node-repo.js

@@ -2,9 +2,13 @@
 
 const LRU = require('lru-cache')
 const retry = require('async').retry
+const Aigle = require('aigle')
+const request = require('request')
 
 const githubClient = require('./github-client')
+const { createPrComment } = require('./github-comment')
 const resolveLabels = require('./node-labels').resolveLabels
+const { Owners } = require('./node-owners')
 const existingLabelsCache = new LRU({ max: 1, maxAge: 1000 * 60 * 60 })
 
 const fiveSeconds = 5 * 1000
@@ -185,10 +189,115 @@ function stringsInCommon (arr1, arr2) {
   return arr1.filter((str) => loweredArr2.indexOf(str.toLowerCase()) !== -1)
 }
 
+async function deferredResolveOwnersThenPingPr (options) {
+  const timeoutMillis = (options.timeoutInSec || 0) * 1000
+  await sleep(timeoutMillis)
+  return resolveOwnersThenPingPr(options)
+}
+
+function getCodeOwnersUrl (owner, repo, defaultBranch) {
+  const base = 'raw.githubusercontent.com'
+  const filepath = '.github/CODEOWNERS'
+  return `https://${base}/${owner}/${repo}/${defaultBranch}/${filepath}`
+}
+
+async function getFiles ({ owner, repo, number, logger }) {
+  try {
+    const response = await githubClient.pullRequests.getFiles({
+      owner,
+      repo,
+      number
+    })
+    return response.data.map(({ filename }) => filename)
+  } catch (err) {
+    logger.error(err, 'Error retrieving files from GitHub')
+    throw err
+  }
+}
+
+async function getDefaultBranch ({ owner, repo, logger }) {
+  try {
+    const data = (await githubClient.repos.get({ owner, repo })).data || { }
+
+    if (!data['default_branch']) {
+      logger.error(null, 'Couldn\' determine default branch')
+      throw new Error('unknown default branch')
+    }
+
+    return data.default_branch
+  } catch (err) {
+    logger.error(err, 'Error retrieving repository data')
+    throw err
+  }
+}
+
+function getCodeOwnersFile (url, { logger }) {
+  return new Promise((resolve, reject) => {
+    request(url, (err, res, body) => {
+      if (err || res.statusCode !== 200) {
+        logger.error(err, 'Error retrieving OWNERS')
+        return reject(err)
+      }
+      return resolve(body)
+    })
+  })
+}
+
+async function resolveOwnersThenPingPr (options) {
+  const { owner, repo } = options
+  const times = options.retries || 5
+  const interval = options.retryInterval || fiveSeconds
+  const retry = fn => Aigle.retry({ times, interval }, fn)
+
+  options.logger.debug('getting file paths')
+  options.number = options.prId
+  const filepathsChanged = await retry(() => getFiles(options))
+
+  options.logger.debug('getting default branch')
+  const defaultBranch = await retry(() => getDefaultBranch(options))
+
+  const url = getCodeOwnersUrl(owner, repo, defaultBranch)
+  options.logger.debug(`Fetching OWNERS on ${url}`)
+
+  const file = await retry(() => getCodeOwnersFile(url, options))
+
+  options.logger.debug('parsing codeowners file')
+  const owners = Owners.fromFile(file)
+  const selectedOwners = owners.getOwnersForPaths(filepathsChanged)
+
+  options.logger.debug('pinging codeowners file')
+  if (selectedOwners.length > 0) {
+    await pingOwners(options, selectedOwners)
+  }
+}
+
+function getCommentForOwners (owners) {
+  return `Review requested:\n\n${owners.map(i => `- [ ] ${i}`).join('\n')}`
+}
+
+async function pingOwners (options, owners) {
+  try {
+    await createPrComment({
+      owner: options.owner,
+      repo: options.repo,
+      number: options.prId,
+      logger: options.logger
+    }, getCommentForOwners(owners))
+  } catch (err) {
+    options.logger.error(err, 'Error while pinging owners')
+    throw err
+  }
+  options.logger.debug('Pinged owners: ' + owners)
+}
+
 exports.getBotPrLabels = getBotPrLabels
 exports.removeLabelFromPR = removeLabelFromPR
 exports.fetchExistingThenUpdatePr = fetchExistingThenUpdatePr
 exports.resolveLabelsThenUpdatePr = deferredResolveLabelsThenUpdatePr
+exports.resolveOwnersThenPingPr = deferredResolveOwnersThenPingPr
 
 // exposed for testability
 exports._fetchExistingLabels = fetchExistingLabels
+exports._testExports = {
+  pingOwners, getCodeOwnersFile, getCodeOwnersUrl, getDefaultBranch, getFiles, getCommentForOwners
+}