Function launchPercyAgent

build-system/tasks/visual-diff/index.js:148–198

* Launches a Percy agent instance. * * @return {!Promise } percy agent instance.

()

 * @return {!Promise<Percy|undefined>} percy agent instance.
 */
async function launchPercyAgent() {
  if (argv.percy_disabled) {
    return;
  }

  const {default: PercyModule} = await PercyModulePromise;
  const percy = await PercyModule.start({
    token: process.env.PERCY_TOKEN,
    loglevel: argv.percy_agent_debug ? 'debug' : 'info',
    port: PERCY_AGENT_PORT,
    config: path.join(__dirname, '.percy.yaml'),
    discovery: {
      launchOptions: {
        executable: locateChromeExecutablePath(),
      },
    },
  });

  await new Promise((resolve, reject) => {
    const percyIsEnabledTimeout = setTimeout(() => {
      log('fatal', 'Percy agent is unreachable after', WAIT_FOR_AGENT_MS, 'ms');
      reject(false);
    }, WAIT_FOR_AGENT_MS);

    while (true) {
      try {
        if (isPercyEnabled()) {
          clearTimeout(percyIsEnabledTimeout);
          log(
            'info',
            'Percy agent is enabled and reachable on port',
            PERCY_AGENT_PORT
          );
          return resolve(true);
        }
      } catch {
        // Ignore transient errors. Promise will reject after WAIT_FOR_AGENT_MS.
      }
    }
  });

  if (process.env['PERCY_TARGET_COMMIT']) {
    log(
      'info',
      'The Percy build is baselined on top of commit',
      cyan(shortSha(process.env['PERCY_TARGET_COMMIT']))
    );
  }

  return percy;
}

/**
 * Adds a test error and logs it if running locally (not as part of CI).