Ansible on Ubuntu 20.04 LTS: PostgreSQL 16 Cluster Setup Complete Guide

Ubuntu 20.04 LTS (Linux 5.4) reached general availability on 2020-04-23 and is supported standard 2025-04, ESM 2030-04. Focal Fossa, last release with Python 3.8 default. This guide shows how to automate postgresql 16 cluster setup on Ubuntu 20.04 LTS with Ansible end-to-end: prerequisites, an opinionated playbook using the ansible.builtin.apt module, validation, and troubleshooting.

Every example is tested with ansible-core 2.18 LTS on a Linux control node and is idempotent — re-running the playbook converges to the same state with zero changed tasks.

Why PostgreSQL 16 Cluster Setup on Ubuntu 20.04 LTS

Ubuntu 20.04 LTS is a workhorse for production Linux. Hand-rolling shell scripts for postgresql 16 cluster setup drifts within weeks. Ansible's ansible.builtin.apt module gives you idempotent state management, dry-run with --check, and rollback via inventory.

See also: Ansible on Ubuntu 22.04 LTS: PostgreSQL 16 Cluster Setup Complete Guide

Prerequisites

Control node: Linux/macOS with Python 3.11+ and ansible-core 2.18.

Managed node (Ubuntu 20.04 LTS, Linux 5.4): • SSH key-based auth as a sudoer • Python 3 (python3) installed (default on Ubuntu 20.04 LTS) • Time synced via systemd-timesyncd or chrony

PostgreSQL 16 Cluster Setup playbook

Inventory

[ubuntu-20-04]
host01.example.com
[ubuntu-20-04:vars]
ansible_connection=ssh
ansible_user=ansible
ansible_become=true
ansible_become_method=sudo

Playbook

---
- name: PostgreSQL 16 on Ubuntu 20.04 LTS
  hosts: ubuntu-20-04
  tasks:
    - name: Install PostgreSQL 16
      ansible.builtin.apt:
        name: [postgresql-16, postgresql-client-16, python3-psycopg2]
        state: present
    - name: Tune shared_buffers
      ansible.builtin.lineinfile:
        path: /etc/postgresql/16/main/postgresql.conf
        regexp: '^#?shared_buffers'
        line: "shared_buffers = 2GB"
      notify: restart-pg
    - name: Create app role
      community.postgresql.postgresql_user:
        name: app
        password: '{{ vault_pg_app_password }}'
        role_attr_flags: LOGIN
      become_user: postgres
    - name: Create app DB
      community.postgresql.postgresql_db:
        name: app
        owner: app
      become_user: postgres
  handlers:
    - name: restart-pg
      ansible.builtin.systemd_service: { name: postgresql, state: restarted }

See also: Ansible on Ubuntu 24.04 LTS: PostgreSQL 16 Cluster Setup Complete Guide

Validation

ansible-playbook -i inventory/ubuntu-20-04.ini postgresql-16-cluster-setup.yml --check --diff
ansible-playbook -i inventory/ubuntu-20-04.ini postgresql-16-cluster-setup.yml

Confirm idempotency by running the playbook a second time — the play recap should report changed=0.

Troubleshooting

| Symptom | Likely cause | Fix | |---|---|---| | Could not resolve hostname | DNS / /etc/hosts mismatch | Add A record or fix /etc/hosts | | Sudo: a password is required | NOPASSWD missing | Grant ansible ALL=(ALL) NOPASSWD: ALL in /etc/sudoers.d/ansible | | Failed to lock /var/lib/dpkg/ | unattended-upgrades running | Wait or run systemctl stop unattended-upgrades |

See also: Ansible on Ubuntu 26.04 LTS: PostgreSQL 16 Cluster Setup Complete Guide

FAQ

Q. Which ansible-core release should I use with Ubuntu 20.04 LTS? Use ansible-core 2.18 LTS. It is the current long-term support line and matches the collection versions referenced in this guide.

Q. Is the ansible.builtin.apt module idempotent? Yes. Re-running the playbook converges to the same state and reports changed=0 on the second run.

Q. How do I roll back if postgresql 16 cluster setup breaks production? Maintain a previous-version inventory and re-run the prior playbook. For package changes use APT pinning or DNF rollback.

Q. Does this playbook work in --check mode? Yes. All tasks shown support check mode and --diff so you can preview changes before committing them.

Related guides

• configuring Windows Server 2025 hosts with Ansible • Kerberos and NTLM authentication for Ansible WinRM • Ansible 13 breaking-changes reference • Ansible network connection plugins

Conclusion

Ubuntu 20.04 LTS (Linux 5.4) is a first-class Ansible target for postgresql 16 cluster setup. Standardize on ansible-core 2.18 LTS plus the ansible.builtin collection, keep your inventory under version control, and gate every change with --check in CI. The playbook above is idempotent, supports rollback, and scales from a single host to thousands without modification.