“apt” module in Ansible playbook execution randomly fails on different hosts each time with message “Failed to lock apt for exclusive operation”

Question

When i try to install a list of packages('apache2', 'libapache2-mod-wsgi', 'python-pip', 'python-virtualenv') on on a group of hosts (app01 and app02), it fails randomly either on app01 or app02. After a first few retries the required packages are already installed on the host. Subsequent execution continue to fail randomly on app01 or app02 instead of returning a simple success.

The ansible controller and hosts are all running ubuntu 16.04

The controller has ansible 2.8.4

I have already set "become: yes" in playbook. I have already tried running apt-get clean and apt-get update. on the hosts

Inventory file

[webserver]
app01 ansible_python_interpreter=python3
app02 ansible_python_interpreter=python3

Playbook

---
- hosts: webserver
  tasks:
    - name: install web components
      become: yes
      apt: 
        name: ['apache2', 'libapache2-mod-wsgi', 'python-pip', 'python-virtualenv'] 
        state: present 
        update_cache: yes

In the first run , the execution fails on host app01

In the second run, the execution fails on host app02

1 st Run

shekhar@control:~/ansible$ ansible-playbook -v playbooks/webservers.yml
Using /home/shekhar/ansible/ansible.cfg as config file

PLAY [webserver] ******************************************************************************

TASK [Gathering Facts] ******************************************************************************
ok: [app01]
ok: [app02]

TASK [install web components] ******************************************************************************
fatal: [app01]: FAILED! => {"changed": false, "msg": "Failed to lock apt for exclusive operation"}
ok: [app02] => {"cache_update_time": 1568203558, "cache_updated": false, "changed": false}

PLAY RECAP ******************************************************************************
app01                      : ok=1    changed=0    unreachable=0    failed=1    skipped=0    rescued=0    ignored=0   
app02                      : ok=2    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

2nd Run

shekhar@control:~/ansible$ ansible-playbook -v playbooks/webservers.yml
Using /home/shekhar/ansible/ansible.cfg as config file

PLAY [webserver] ******************************************************************************

TASK [Gathering Facts] ******************************************************************************
ok: [app01]
ok: [app02]

TASK [install web components] ******************************************************************************
fatal: [app02]: FAILED! => {"changed": false, "msg": "Failed to lock apt for exclusive operation"}
ok: [app01] => {"cache_update_time": 1568203558, "cache_updated": false, "changed": false}

PLAY RECAP ******************************************************************************
app01                      : ok=2    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0   
app02                      : ok=1    changed=0    unreachable=0    failed=1    skipped=0    rescued=0    ignored=0

Might be very similar to this question. Make sure you disabled automatic updates on your hosts. More generally (if automatic update is not the problem), check what is causing apt to launch and acquire a lock on your hosts outside of you running your playbook. — Zeitounator
Are you sure that app01 and app02 are 2 different hosts! otherwise it sounds normal that the 2 jobs fight against each other… — xenlo
@xenlo : You are right. My bad. My /etc/hosts file was populated incorrectly with app01 and app02 pointing to same machine, although in reality they are different machine. Once i fixed that, the issue disappeared. In such cases i do not know the stackoverflow etiquette. Should i delete the question? or you will you post your comment as answer so that i can upvote it and accept the answer. — nitin3685
@nitin3685, no idea niether how we should do. But your proposition sounds, me copying my comment as answer, looks good to me. — xenlo

xenlo xenlo · Accepted Answer · 2019-09-12T11:24:39

The behavior is a bit strange… one succeed, and other failing each time.

My guess is that your app01 and app02 are actually the same host! If so, it sounds normal that the 2 jobs fight against each other.

“apt” module in Ansible playbook execution randomly fails on different hosts each time with message “Failed to lock apt for exclusive operation”

1 Answers