title: How can I run an Ansible block one host at a time?
body: <p>I have a playbook with something like this:</p>
  <pre class="lang-yaml prettyprint-override"><code>- name: Do this all one host at a time
    block:
      - name: Task A
        # do task A
      
      - name: Task B
        # do task B
    throttle: 1
  </code></pre>
  <p>I expect <code>throttle: 1</code> to limit execution to one of the hosts at a time.  It does this, but instead of running the whole block on host 1, then the whole block on host 2, etc. it runs Task A on host 1, Task A on host 2, Task B on host 1, Task B on host 2.</p>
  <p>How can I run the entire block on each host in the group, one at a time?</p>
  <p>(Note: there are other tasks in the playbook that should not run serially, hence not having the entire playbook run this way.)</p>