Ansible adhoc command in sequence

Question

I want to run ansible adhoc command on a list of EC2 instances. I want ansible to run it in sequence but ansible runs them in random. For example:

13:42:21 @cnayak ansible :► ansible aws -a "hostname"
ec2 | SUCCESS | rc=0 >>
ip-172-31-36-255

ec3 | SUCCESS | rc=0 >>
ip-172-31-45-174

13:42:26 @cnayak ansible :► ansible aws -a "hostname"
ec3 | SUCCESS | rc=0 >>
ip-172-31-45-174

ec2 | SUCCESS | rc=0 >>
ip-172-31-36-255

Any way to make them run in order?

score 13 · Accepted Answer · answered May 25 '16 at 13:48

13

By default ansible runs tasks in parallel. If you want them to be executed serially then you can limit number of workers running at the same time by using "--forks" option.

Adding "--forks 1" to your ansible invocation should run your command sequentially on all hosts (in order defined by inventory).

answered May 25 '16 at 13:48

bjakubski

1,477
10
9

ansible aws -a "hostname" -f 1 worked for me, thanks! – Chandan Nayak May 25 '16 at 14:20

score 7 · Answer 2 · answered Jun 06 '16 at 17:32

7

You can use the forks with adhoc command and serial: 1 inside the playbook.

On adhoc command:

ansible aws -a "hostname" --forks=1

Inside the playbook:

- hosts: aws
  become: yes
  gather_facts: yes
  serial: 1
  tasks:
    - YOUR TASKS HERE

answered Jun 06 '16 at 17:32

Arbab Nazar

22,378
10
76
82

score 2 · Answer 3 · answered Nov 30 '18 at 00:06

--forks=1 hasn't been sorting inventory for me in recent versions of ansible (2.7)

Another approach I find useful is using the "oneline" output callback, so I can use the standard sort and grep tools on the output:

ANSIBLE_LOAD_CALLBACK_PLUGINS=1 \
ANSIBLE_STDOUT_CALLBACK=oneline \
ansible \
  -m debug -a "msg={{ansible_host}}\t{{inventory_hostname}}" \
  | sort \
  | grep -oP '"msg": \K"[^"]*"' \
  | xargs -n 1 echo -e

This has been useful for quick-n-dirty reports on arbitrary vars or (oneline) shell command outputs.

Ansible adhoc command in sequence

3 Answers3