Deploying a PostgreSQL Cluster with Patroni and HAProxy on Ubuntu 24.04
A Patroni cluster needs an odd number of nodes to maintain quorum — with 3 nodes, losing 1 still leaves a majority, so the cluster keeps running. This guide builds a 3-node PostgreSQL cluster on Ubuntu 24.04 with Patroni handling replication and automatic failover, etcd as the coordination store, and HAProxy load-balancing client connections — all secured with TLS. Prerequisites: three Ubuntu 24.04 servers (2 vCPU / 4GB RAM minimum) with PostgreSQL installed, non-root sudo access, and a domain with three A records: node1.example.com , node2.example.com , node3.example.com . Replace these placeholders with your actual subdomains throughout. Install Dependencies Run on all three nodes unless noted otherwise. 1. Install packages: $ sudo apt update $ sudo apt install haproxy certbot pipx -y $ sudo pip3 install --break-system-packages 'patroni[etcd3]' psycopg2-binary psycopg 2. Install etcd: $ wget https://github.com/etcd-io/etcd/releases/download/v3.6.4/etcd-v3.6.4-linux-amd64.tar.gz $ tar -xvf etcd-v3.6.4-linux-amd64.tar.gz $ sudo mv etcd-v3.6.4-linux-amd64/etcd etcd-v3.6.4-linux-amd64/etcdctl /usr/local/bin/ 3. Open firewall ports — 80 (Certbot), 2379/2380 (etcd), 5432/5433 (PostgreSQL + Patroni-managed PostgreSQL), 8008/8009 (Patroni REST API): $ sudo ufw allow 80,2379,2380,5432,5433,8008,8009/tcp $ sudo ufw reload $ sudo ufw status Configure SSL Certificates 1. Request a certificate per node (run on each node for its own subdomain): $ sudo certbot certonly --standalone -d node1.example.com -m admin@example.com --agree-tos --no-eff 2. Create a cert-prep script on each node (set HOSTNAME to that node's subdomain): $ sudo nano /usr/local/bin/prepare-ssl-certs.sh #!/bin/bash HOSTNAME = "node1.example.com" # Update for each node CERT_DIR = "/etc/letsencrypt/live/ $HOSTNAME " ARCHIVE_DIR = "/etc/letsencrypt/archive/ $HOSTNAME " getent group ssl-users > /dev/null || sudo groupadd ssl-users for user in etcd patroni haproxy postgres ; do if ! id " $user " > /dev/null 2>&1 &&