gpg

2023 Update: Ansible now has the ansible.builtin.deb822_repository module, which can add keys and repositories in one task. It's a little more complex than the old way, and requires Ansible 2.15 or later. See some common deb822_repository examples here, for example, the Jenkins tasks below can be consolidated (though the structure of the templated vars would need reworking):

- name: Add Jenkins repo using key from URL.
  ansible.builtin.deb822_repository:
    name: jenkins
    types: [deb]
    uris: "https://pkg.jenkins.io/debian-stable"
    components: [binary]
    signed_by: https://pkg.jenkins.io/debian-stable/jenkins.io-2023.key
    state: present
    enabled: true

For many packages, like Elasticsearch, Docker, or Jenkins, you need to install a trusted GPG key on your system before you can install from the official package repository.