index.js

const yaml = require('js-yaml')
const { createProbot } = require('probot')

/**
 * This is the main entrypoint to your Probot app
 * @param {import('probot').Probot} app
 */
module.exports = (app) => {
  app.log.info('Yay, the app was loaded!')
  console.log(`APP_ID is ${process.env.APP_ID}`)

  app.on('repository.created', async (context) => {
    const owner = context.payload.repository.owner.login
    const repo = context.payload.repository.name
    context.log.debug(`Repository ${repo} created in org ${owner}`)
    
    // Loading the setting file in <org>/.github-private/permissions.app.yml 
    try {
      const settingFile = await context.octokit.repos.getContent({
        'owner': owner,
        'repo': '.github-private',
        'path': 'permissions.app.yml'
      })
      
      app.log.info('Got the settings')

      const buff = Buffer.from(settingFile.data.content, settingFile.data.encoding) // encoding should be 'base64'
      const settings = yaml.load(buff.toString())
      context.log.debug(`Settings retrieved: ${JSON.stringify(settings)}`)
    
      context.log.debug(`Received content ${settingFile.data.content} with encoding ${settingFile.data.encoding}`)
      
      for (const [permission, teamArray] of Object.entries(settings)) {
        for(const team of teamArray) {
          context.log.debug(`Setting ${permission} permission to team ${team} on repo ${repo} in org ${owner}`)
          
          try {
            await context.octokit.teams.addOrUpdateRepoPermissionsInOrg({
              'org': owner,
              'team_slug': team,
              'owner': owner,
              'repo': repo,
              'permission': permission
            })
          } catch(error) {
            context.log.error(`Failed to set permission ${permission} for team ${team} on ${owner}/${repo} with message: ${error.message}`)
          }
        }
      }
    } catch(error) {
      context.log.error(`Failed to retrieve settings: ${error.message}`)
    }
  })
}