const createApp = require('github-app');

const app = createApp({
  // Your app id
  id: 987,
  // The private key for your app, which can be downloaded from the
  // app's settings: https://github.com/settings/apps
  cert: require('fs').readFileSync('private-key.pem')
});

//Modify value according to getInstallations return(example in asApp section)
var installationId = 99999;

app.asInstallation(installationId).then(github => {
  github.issues.createComment({
    owner: 'foo',
    repo: 'bar',
    number: 999,
    body: 'hello world!'
  });
});

app.asApp().then(github => {
  console.log("Installations:")
  github.apps.getInstallations({}).then(console.log);
});