Ansible with_items single or multiple module call

ansible

When I setup an ansible task with with_items to install software with the apt module like this:

- name: ensure base packagase are installed
  apt:
    name: "{{ item }}"
    state: latest
    update_cache: yes
  with_items: "{{ system_base_packages }}"

Will the apt module be called multiple times as well as the update_cache? Or is this a single call to the module?

My main concern is that I do not want to update the cache multiple times for every software inside the array to be installed.

Best Answer

The following modules apk, apt, dnf, package*, pacman, pkgng, yum, zypper are smart to squash your items into single run.

See this SO answer for links.

package as of Ansible 2.3 (2017-04-12) no longer has it's items squashed. This can be overcome by specifying squash_actions= in the [defaults] section of your ansible.cfg file.

Related Solutions

Callbacks or hooks, and reusable series of tasks, in Ansible roles

I'm not familiar with PostgreSQL so I'm unsure of the contents of the various configuration files you mentioned, but if you need to allow multiple roles to contribute to a single configuration file, I've accomplished this in one of two ways depending on what the configuration file supports:

Use a configuration file with lots of include statements to include additional configuration files located in sub-directories. This works well with something like Apache for rewrite rules, application-specific configuration directives, and virtual hosts.
Assemble the configuration file from multiple partial configuration files stored in a directory using the assemble module. I've used this method to construct a master.cf file for Postfix as I had a postfix role and another role that needed to add to the Postfix master.cf file. So I modified the postfix role to create a /etc/postfix/master.d directory and a handler that assembles the files in that directory into a master.cf file. Unfortunately, as you pointed out, since I can't call the handler in the postfix role from another role, I had to duplicate that handler in my additional role. It's slightly less than idea but it works and it's idempotent.

Ansible command with_items

Have a look at https://github.com/ansible/ansible/issues/8260 for the details on why this change in behaviour was made (to prevent additional arguments being injected in the command module). The following format should work:

- name: Generate postfix dhparams
  command: "{{ item.command }} creates={{ item.file}}"
  with_items:
    - { command: 'openssl gendh -out /etc/postfix/dh_512.pem -2 512', file: '/etc/postfix/dh_512.pem' }
    - { command: 'openssl gendh -out /etc/postfix/dh_2048.pem -2 2048', file: '/etc/postfix/dh_2048.pem' }
  notify: Reload postfix

Best Answer

Related Solutions

Callbacks or hooks, and reusable series of tasks, in Ansible roles

Ansible command with_items

Related Topic