Find the number of processes using Ansible

Below is my playbook that dumps the processes matching .*httpd.*|.*sjsws.*|.*java.*|.*docker.*|.*node.*

Playbook:

   vars:
     grepelement: ".*httpd.*|.*sjsws.*|.*java.*|.*docker.*|.*node.*"

     - name: "Check processes on destination"
       ignore_errors: yes
       command: ps auxwww
       register: ps_out

     - set_fact:
         processdump: "{{ ps_out.stdout | regex_findall(grepelement) }}"

     - set_fact:
         processdumpcount: "{{ ps_out.stdout.split() | length }}"

Unfortunately, although only 4 processes are running the count seems to print more than 1000s which could be the number of characters in the output.

I also tried the below but this too prints more than the number of processes running.

     - set_fact:
         processdumpcount: "{{ ps_out.stdout_lines | length }}"

I can use command: ps auxwww | wc -l as a solution but prefer solution with a single ps command.

Can you please suggest?

Solution

You need to check the length of processdump register for the count not ps_out.stdout_lines

  - set_fact:
      processdumpcount: "{{ processdump  | length }}"

Note that ps_out is holding on to all the processes running on the system and later you are operating ps_out with regex_findall to filter out the matching processes to processdump. you need to take length of processdump register.

Minimal working example:

My system process counts:

 ps auxwww |wc -l
287
 ps auxwww |grep -E ".*httpd.*|.*sjsws.*|.*java.*|.*docker.*|.*node.*" |grep -v grep |wc -l
3

playbook:

---

- name: Sample playbook
  connection: local
  #  gather_facts: false
  hosts: localhost
  vars:
    grepelement: ".*httpd.*|.*sjsws.*|.*java.*|.*docker.*|.*node.*"
  tasks:
  - name: "Check processes on destination"
    ignore_errors: yes
    command: ps auxwww
    register: ps_out

  - set_fact:
     processdump: "{{ ps_out.stdout | regex_findall(grepelement) }}"

  - set_fact:
      processdumpcount: "{{ processdump  | length }}"

  - debug: msg="{{ processdumpcount }}"

Above playbook would result in:

PLAY [Sample playbook] **********************************************************************************************************************************************

TASK [Gathering Facts] **********************************************************************************************************************************************
ok: [localhost]

TASK [Check processes on destination] *******************************************************************************************************************************
changed: [localhost]

TASK [set_fact] *****************************************************************************************************************************************************
ok: [localhost]

TASK [set_fact] *****************************************************************************************************************************************************
ok: [localhost]

TASK [debug] ********************************************************************************************************************************************************
ok: [localhost] => {
    "msg": "3"
}

PLAY RECAP **********************************************************************************************************************************************************
localhost                  : ok=5    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0