Set up Logrotate with Ansible

TLDR

Logrotate can really come in handy when you need to manage logfiles on your Linux machine. And this tutorial shows you how to set up logrotate via Ansible.

Example - Managing Rails Logfile with Logrotate

Details

Triggers hourly
Rotate when log file is bigger than 100M
Only keep 10 copies

Configuring Ansible for Logrotate

roles/logrotate/tasks/main.yml

- name: set up logrotate for rails log
  template:
    src: rails.j2
    dest: /etc/logrotate.d/rails
    owner: root
    group: root
    mode: 0644
 
- name: ensure logrotate is in /etc/cron.hourly
  file:
    src: /etc/cron.daily/logrotate
    dest: /etc/cron.hourly/logrotate
    state: link
    force: yes
    mode: 0755 # the file needs to be excutable

roles/logrotate/templates/rails.j2

Modify /path/to/your/rails/log/{{ each_group.rails.env }}.log to your logfile's path on your machine.

/path/to/your/rails/log/{{ each_group.rails.env }}.log {
    size 100M             # triggers when file is bigger than 100M
    dateext               # use date extension
    dateformat -%Y%m%d-%s # the extention format
    rotate 10             # keep 10 files
    copytruncate          # truncates the original file
    missingok             # does not throw error if the file is missing
    notifempty            # does not rotate if the file is empty
}

Provisioning Logrotate with Ansible

Refer to Executing playbooks.

Bonus

Checking whether Logrotate can be Called by Cron

# Should print "/etc/cron.hourly/logrotate"
$ run-parts --test /etc/cron.hourly

Getting File/Directory Permission Numerical Value in Linux

I usually use sites like Chmod Calculator to map values.

$ stat --format '%a' your-filename

Finding out when cron.hourly Really Executes

$ cat /etc/cron.d/0hourly