postStatus.js

const octokit = require('@octokit/rest');
const jsonwebtoken = require('jsonwebtoken');

const PEM = `-----BEGIN RSA PRIVATE KEY-----
<REDACTED>
-----END RSA PRIVATE KEY-----`;

function generateJwtToken() {
  // Sign with RSA SHA256
  return jsonwebtoken.sign(
    {
      iat: Math.floor(new Date() / 1000),
      exp: Math.floor(new Date() / 1000) + 60,
      iss: <the id of your github app>,
    },
    PEM,
    { algorithm: 'RS256' },
  );
}

module.exports = async function postStatus({
  repo,
  owner,
  sha,
  installationId,
  triggeredByUrl,
}) {
  const octokitClient = octokit();
  octokitClient.authenticate({
    type: 'integration',
    token: generateJwtToken(),
  });

  const { data: { token } } = await octokitClient.apps.createInstallationToken({
    installation_id: installationId,
  });

  octokitClient.authenticate({ type: 'token', token });

  await octokitClient.repos.createStatus({
    owner,
    repo,
    sha,
    state,
    context: 'Happo',
    target_url: triggeredByUrl,
    description: 'All good from over here',
    headers: {
      accept: 'application/vnd.github.machine-man-preview+json',
    },
  });
 };