Arvados

source:tools/ansible/requirements.txt currently declares we need:

ansible-core ~= 2.16.14

And indeed, our Ansible code needs to continue working on Ansible 2.16, because that is the last version that supports Python 3.6 on managed nodes, and that's what RHEL 8 uses.

However, Ansible 2.16 does not support Python 3.13 on the control node. We want that for Debian 13 support. And Ubuntu 26.04 coming out soon will have Python 3.14.

The main requirement of this ticket is to update the requirement to support a range of Ansible versions. Ideally we would write:

ansible-core >= 2.16.0, < 2.21

and confirm that our playbooks work with the latest version on the right. We can use a smaller range if necessary. However:

• The end of the range must allow the user to install at least one currently supported version in the ansible-core support matrix. As of this writing that's 2.18.
• 2.18 is going to go out of support pretty soon, so supporting 2.19 would be a lot better. That version is much stricter about having boolean conditionals, so you might need to update some our playbook code to meet the new requirements. Ansible provides a porting guide for this. I don't think it's going to be too difficult, we're reasonably good about this already, but that is the main thing to look out for. If this becomes very hairy, please flag that at standup or in the ticket, and we can talk through our options.
• Arvados developers must get the oldest version in order to build Docker images for the oldest distros. The easiest way to do that is to munge the requirements in arvados_ansible. In source:tools/ansible/roles/arvados_ansible/tasks/main.yml after "Upload requirements" add a task like:

  - name: Install minimum Ansible version for Arvados development
    # Add this variable to role defaults with default true
    when: "{{ arvados_ansible_minimum_version|bool }}" 
    ansible.builtin.replace:
      path: "{{ requirements_tempfile.path }}" 
      regexp: "^ansible-core\\s*>=" 
      replace: "ansible-core ~=" 
  

Test install-dev-tools.yml by installing on a fresh VM of your choice. Test install-arvados-cluster.yml by running test-provision-ansible on your branch.