I'm running Ansible 2.2, but can upgrade if it helps.

I saw this and was pretty excited, but it doesn't seem to be in this (or any) version of Ansible documentation.

The problem I'm trying to solve is I've got 1000 users that I need to manage on a Centos box.

It takes quite a while to run this task serially. And even more annoying, everything shows up as changed because the "expires" command on the user module always marks the thing as changed.

this also looked promising, but it took the same amount of time to run each command in the with_items loop and didn't go any faster (I never bothered to wait long enough to get to the end).

Skipping tasks is fast now (a lot faster than it was in Ansible 2.0), if I can't figure out how to make this work in parallel, I think I'll go back and figure out how to skip pointless tasks and if all else fails, I'll write my own module. But it seems like I should be able to do all this faster in Ansible.

This is what I want to run in parallel, host_authorizations is a list of usernames and other data.

  - name: Create/modify OS user accounts
    user: name={{ item.username }} group=sshusers shell=/bin/bash home="/home/selinux-modules/{{ item.username }}" state=present expires={{item.expiredate|default(omit)}}
    with_items: "{{ host_authorizations }}"
    tags: full_maintenance
  • Please provide a code snippet. Otherwise it is hard to help.
    – 030
    Commented Apr 11, 2018 at 18:31
  • @030 there's a snippet, I guess it helps a bit for context. I'm more interested conceptually if there really is a way to run tasks (in a loop) in parallel on the same host. I know I could do a ton of individual things with async, but not so much with with_items.
    – Peter Turner
    Commented Apr 11, 2018 at 18:45
  • So basically if 1000 users have to be created then it should be finished as fast as creating just one user. Interesting, why not using something like LDAP?
    – 030
    Commented Apr 11, 2018 at 20:53
  • 1
    Seriously, you're heading toward a path of pain, I don't think anyone handle more than a dozen of accounts with local account base, as soon as the number of users grow, I assume everyone move to a centralized accounting system, usualy some ldap backend (could be active directory) and then set the expiry time and public key as attributes of this central base then use things like sss_ssh_authorizedkeys to let the ssh server get the authorized keys from this central base.
    – Tensibai
    Commented Apr 12, 2018 at 11:32
  • 2
    I disagree this is what ansible is for (hint being it doesn't do bulk user creation/management). I stand by the point that accounts should not be managed on local account bases at large volume (fact they are not human accounts is irrelevant to the problem anyway)
    – Tensibai
    Commented Apr 12, 2018 at 14:33

3 Answers 3


As @webKnja mentioned this is possible with async mode. I have recently discovered it myself and learned that you can use it in 3 different ways depending on your needs.

  1. Execute and poll the results, notice the poll:5, This will poll the results every 5 seconds. You may save some time with this method.

     - name: My long runing task
         ip: "{{item.fabric}}"
         username: "{{user}}"
         password: "{{password}}"
         secret: "{{secret}}"
       loop: "{{zoning_list}}"
       register: _alias_vc_0
       async: 60
       poll: 5
  2. Fire and forget poll: 0, This is very quick option since Ansible it's just shooting out those tasks. The down side is that we don't know what was the outcome of the task i.e. changed: True/False. Of course it's a downside if you care about the feedback ;).

     name: My long runing task
       ip: "{{item.fabric}}"
       username: "{{user}}"
       password: "{{password}}"
       secret: "{{secret}}"
     loop: "{{zoning_list}}"
     register: _alias_vc_0
     async: 60
     poll: 0
  3. Fire and forget with async_status, the syntax for the task is the same as example 2 whowever it will require additional task async_status. This is my favorite since it's relatively fast (faster then normal looping or the execute and poll) and allows you to capture the feedback although will need to deal with new register for your async_task.

retries: 20 -- how many attempts before failing.

delay: 2 -- how many second to wait between polls.

    - name: My long runing task
        ip: "{{item.fabric}}"
        username: "{{user}}"
        password: "{{password}}"
        secret: "{{secret}}"
      loop: "{{zoning_list}}"
      register: _alias_vc_0
      async: 60
      poll: 0

    - name: Wait for My long running task to finish
        id: "{{ item.ansible_job_id }}"
        #jid: "{{ item.ansible_job_id }}" # ansible version > 2.8
      register: _jobs_alias_vc_0
      retries: 20
      delay: 2
      until: _jobs_alias_vc_0.finished
      loop: "{{_alias_vc_0.results}}"

A word of caution, depending on the task yo may not be able to use the async option. I had examples where I was interacting with system which was not able to handle multiple requests for the same resource. I found async option best working if I have to perform the same task across multiple hosts. That's where I was able to "save" the most time.

Since you posted the link to Ansible documentation in the question I'm not going to do that.

  • @chicks you might want to change the poll value to 0 in example 3. This is an amazing explanation!! Thnx. Commented May 3, 2019 at 18:43
  • @DebanjanBasu Anybody can make suggested edits. I might be the one who approves it in the review queues, but you should get credit for the edit itself.
    – chicks
    Commented May 3, 2019 at 19:37
  • One character edits aren't allowed sadly! :( Commented May 8, 2019 at 10:32
  • 3
    Option 3 works great, thanks! One comment though: as of at least Ansible 2.8, async_status requires jid, not id. Commented May 31, 2019 at 16:24
  • Although correct, this method fails when you enable jinja2_native unless Ansible includes a fix. Unfortunately, Ansible, up to and including v2.14.3, does not have it.
    – Stephan
    Commented Mar 9, 2023 at 10:14

It is possible to achieve this using async mode. Please find some references for how to do this below.



- name: Run tasks in parallel
  hosts: localhost
  connection: local
  gather_facts: no
    - name: Pretend to create instances
      command: "sleep {{ item }}"  # Instead of calling a long running operation at a cloud provider, we just sleep.
        - 6
        - 8
        - 7
      register: _create_instances
      async: 600  # Maximum runtime in seconds. Adjust as needed.
      poll: 0  # Fire and continue (never poll)

    - name: Wait for creation to finish
        jid: "{{ item.ansible_job_id }}"
      register: _jobs
      until: _jobs.finished
      delay: 5  # Check every 5 seconds. Adjust as you like.
      retries: 10  # Retry up to 10 times. Adjust as needed.
      with_items: "{{ _create_instances.results }}"
  • While those links may answer the question if they come to break there's nothing left in your answer for future readers, please try to showcase how this would help solving the problem with your own words/exemple and leave the links for more detailed informations only.
    – Tensibai
    Commented Sep 17, 2018 at 7:46
  • yeah, I can't mark this as the answer until A.) I test it and B.) relevant code is placed in here. But thank you for pointing me in this direction nevertheless.
    – Peter Turner
    Commented Sep 17, 2018 at 13:31
  • Sorry, I was it hurry :) Commented Sep 19, 2018 at 11:40
  • @PeterTurner I believe the code has been added since. Commented Feb 21, 2022 at 13:03

To answer your question: No, as of now Ansible can't run loops in parallel.

I'd use newusers instead, which is made for bulk user creation. Create a file with all users in it, copy it over to the host, and run newusers /path/to/user/list in a command or shell task.

For example:

- name: Create multiple users
  shell: newusers /path/to/user/list && touch /path/to/user/ansible-users-added
    creates: /path/to/user/ansible-users-added

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