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Initial setup for high availability

This guide provides instructions on how to set up a highly available PostgreSQL cluster with Patroni. This guide relies on the provided architecture for high-availability.

Considerations

  1. This is an example deployment where etcd runs on the same host machines as the Patroni and PostgreSQL and there is a single dedicated HAProxy host. Alternatively etcd can run on different set of nodes.

    If etcd is deployed on the same host machine as Patroni and PostgreSQL, separate disk system for etcd and PostgreSQL is recommended due to performance reasons.

  2. For this setup, we will use the nodes that have the following IP addresses:

    Node name Public IP address Internal IP address
    node1 157.230.42.174 10.104.0.7
    node2 68.183.177.183 10.104.0.2
    node3 165.22.62.167 10.104.0.8
    HAProxy1 112.209.126.159 10.104.0.6
    HAProxy2 134.209.111.138 10.104.0.5
    HAProxy3 134.60.204.27 10.104.0.3
    backup 97.78.129.11 10.104.0.9

    We also need a virtual IP address for HAProxy: 203.0.113.1

!!! important

We recommend not to expose the hosts/nodes where Patroni / etcd / PostgreSQL are running to public networks due to security risks.  Use Firewalls, Virtual networks, subnets or the like to protect the database hosts from any kind of attack.

Configure name resolution

It’s not necessary to have name resolution, but it makes the whole setup more readable and less error prone. Here, instead of configuring a DNS, we use a local name resolution by updating the file /etc/hosts. By resolving their hostnames to their IP addresses, we make the nodes aware of each other’s names and allow their seamless communication.

Run the following commands on each node.

  1. Set the hostname for nodes. Change the node name to node1, node2, node3, HAProxy1, HAProxy2 and backup, respectively:

    $ sudo hostnamectl set-hostname node1

  2. Modify the /etc/hosts file of each node to include the hostnames and IP addresses of the remaining nodes. Add the following at the end of the /etc/hosts file on all nodes:

    # Cluster IP and names

10.104.0.7 node1    
10.104.0.2 node2    
10.104.0.8 node3    
10.104.0.6 HAProxy1 
10.104.0.5 HAProxy2 
10.104.0.3 HAProxy3
10.104.0.9 backup

Configure Percona repository

To install the software from Percona, you need to subscribe to Percona repositories. To do this, you require percona-release - the repository management tool.

Run the following commands on each node as the root user or with sudo privileges.

  1. Install percona-release

    === ":material-debian: On Debian and Ubuntu"

     --8<-- "percona-release-apt.md"

    === ":material-redhat: On RHEL and derivatives"

     --8<-- "percona-release-yum.md"

  2. Enable the repository:

    $ sudo percona-release setup ppg{{pgversion}}

Next steps

Set up etcd :material-arrow-right:{.md-button}