How to kill a running process using ansible?

Question

I have an ansible playbook to kill running processes and works great most of the time!, however, from time to time we find processes that just can't be killed so, "wait_for" gets to the timeout, throws an error and it stops the process.

The current workaround is to manually go into the box, use "kill -9" and run the ansible playbook again so I was wondering if there is any way to handle this scenario from ansible itself?, I mean, I don't want to use kill -9 from the beginning but I maybe a way to handle the timeout?, even to use kill -9 only if process hasn't been killed in 300 seconds? but what would be the best way to do it?

These are the tasks I currently have:

- name: Get running processes
  shell: "ps -ef | grep -v grep | grep -w {{ PROCESS }} | awk '{print $2}'"
  register: running_processes

- name: Kill running processes
  shell: "kill {{ item }}"
  with_items: "{{ running_processes.stdout_lines }}"

- name: Waiting until all running processes are killed
  wait_for:
    path: "/proc/{{ item }}/status"
    state: absent
  with_items: "{{ running_processes.stdout_lines }}"

Thanks!

Tinworks

Use shell only when shell functionality is required. command: "kill {{ item }}" – Rupe

Answer 1

You could ignore errors on wait_for and register the result to force kill failed items:

- name: Get running processes
  shell: "ps -ef | grep -v grep | grep -w {{ PROCESS }} | awk '{print $2}'"
  register: running_processes

- name: Kill running processes
  shell: "kill {{ item }}"
  with_items: "{{ running_processes.stdout_lines }}"

- wait_for:
    path: "/proc/{{ item }}/status"
    state: absent
  with_items: "{{ running_processes.stdout_lines }}"
  ignore_errors: yes
  register: killed_processes

- name: Force kill stuck processes
  shell: "kill -9 {{ item }}"
  with_items: "{{ killed_processes.results | select('failed') | map(attribute='item') | list }}"

Kiva

Can I use this in a bog post? (with link back to this reply) @Eric – Traditional

Btw, this will wait for {{timeout}} seconds per process, so 5 processes will result in 5*{{timeout}}. I wonder if this can be improved via async.. – Traditional

Can you please explain "{{ killed_processes.results | select('failed') | map(attribute='item') | list }}" ? I am new to Ansible and I am looking for a set of tasks that would kill a set of processes reliably. – Kerk

Instead of using the long ps command ps -ef | grep -v grep | grep -w {{ PROCESS }} | awk '{print $2}' you can do it all with ps ps -C {{ PROCESS }} -o pid= This will only print the pid of the command PROCESS. the "-C {{ PROCESS }}" is equivalent to the first 3 commands in the pipe. the "-o pid=" prints only the PID numbers without the header. An even easier solution is "pgrep {{ PROCESS }}", which does the same thing. $0.02 – Backwash

Answer 2

Use pkill(1) instead of grep+kill.

Definitive

Answer 3

The killall command has a wait option that might be useful.

Install psmisc:

tasks:
  - apt: pkg=psmisc state=present

Then use killall like this:

tasks:
  - shell: "killall screen --wait"
    ignore_errors: true # In case there is no process

-w, --wait: Wait for all killed processes to die. killall checks once per second if any of the killed processes still exist and only returns if none are left.

Spanos

So elegant compared to the other answers! – Madlin

Answer 4

After some investigations and struggling with ansible_linter, below an alternative way (eg. without use of ignore_error)

- name: "disable and stop PROCESS"
  service:
    name: PROCESS
    enabled: no
    state: stopped
  tags:
    - stop

- name: "evaluate running PROCESS processes from remote host"
  command: "/usr/bin/pgrep PROCESS"
  register: running_PROCESS
  failed_when: running_PROCESS.rc > 1
  changed_when: 
    - running_PROCESS.rc == 0
  tags:
    - stop

- name: "pkill PROCESS running processes"
  command: "/usr/bin/pkill PROCESS"
  register: kill_PROCESS
  changed_when: kill_PROCESS.rc == 0
  when: running_PROCESS.stdout_lines | length > 0
  tags:
    - stop

- name: "check PROCESS processes"
  wait_for:
    path: "/proc/{{ item }}/status"
    state: absent
  with_items: "{{ running_PROCESS.stdout_lines }}"
  when: running_PROCESS.stdout_lines | length > 0
  tags:
    - stop

- name: "force kill stuck PROCESS processes"
  command: "/usr/bin/pkill -9 PROCESS"
  register: kill9_PROCESS
  changed_when: kill9_PROCESS.rc == 0
  failed_when: kill9_PROCESS.rc > 1
  when:
    - running_PROCESS.stdout_lines | length > 0
  tags:
    - stop

Debutant

Answer 5

This Code Worked for me

- hosts: ubuntu
  become: yes
  tasks:
  - name: Get Apache PIDs
    shell:
      cmd: ps -ef | grep -v grep | grep -w apache2 | awk '{print $2}' | awk 'FNR == 1 {print}'
      warn: false
    changed_when: false
    check_mode: false
    register: apache_pids

  - name: Kill running processes
    shell: "kill {{ item }}"
    with_items:
    - "{{ apache_pids.stdout_lines }}"

  - name: Show PIDs
    debug:
      var: apache_pids

Joviality