This section describes the process for converting a standalone PostgreSQL instance into a Patroni cluster.

To deploy a Patroni cluster without using a pre-existing PostgreSQL instance, see Running and Configuring instead.


A Patroni cluster can be started with a data directory from a single-node PostgreSQL database. This is achieved by following closely these steps:

  1. Manually start PostgreSQL daemon
  2. Create Patroni superuser and replication users as defined in the authentication section of the Patroni configuration. If this user is created in SQL, the following queries achieve this:
  1. Start Patroni (e.g. patroni /etc/patroni/patroni.yml ). It automatically detects that PostgreSQL daemon is already running but its configuration might be out-of-date.
  2. Ask Patroni to restart the node with patronictl restart cluster-name node-name .


  1. During Patroni startup, Patroni complains that it cannot bind to the PostgreSQL port.

You need to verify listen_addresses and port in postgresql.conf and postgresql.listen in patroni.yml . Don’t forget that pg_hba.conf should allow such access.

  1. After asking Patroni to restart the node, PostgreSQL displays the error message could not open configuration file "/etc/postgresql/10/main/pg_hba.conf": No such file or directory

It can mean various things depending on how you manage PostgreSQL configuration. If you specified postgresql.config_dir , Patroni generates the pg_hba.conf based on the settings in the bootstrap section only when it bootstraps a new cluster. In this scenario the PGDATA was not empty, therefore no bootstrap happened. This file must exist beforehand.