Hubspot/Singularity `extraScript` config hack for adding links in the menu to instances of a given service

singularity_menu_extra_script.js

<script>
 fetch('/singularity/api/tasks/ids/request/{{ Environment }}_{{ Service }}')
  .then(response => response.json()).then((taskIDs) => {
    Object.values(taskIDs.healthy).forEach(function(task) {
      fetch('/singularity/api/tasks/task/' + task.id)
        .then(response => response.json()).then((taskInfo) => {
          let host = taskInfo.taskId.host.replace(/_/g, '-');
          let port = taskInfo.mesosTask.container.docker.portMappings[0].hostPort;
          let a = document.createElement('a');
          a.textContent = '{{ Service }} at ' + host + ':' + port;
          a.href = 'http://' + host + ':' + port;
          let li = document.createElement('li');
          li.appendChild(a);
          document.getElementsByClassName('navbar-brand')[0].nextSibling.appendChild(li);
        });
    });
  });
</script>