# Installation

## Pre-requirements for Mac OS

To install requirements on a Mac, run the following:

    brew install postgresql etcd haproxy libyaml python

## Psycopg

Starting from psycopg2-2.8 the binary version of psycopg2 will no longer be installed by default. Installing it from the source code requires C compiler and postgres+python dev packages. Since in the python world it is not possible to specify dependency as `psycopg2 OR psycopg2-binary` you will have to decide how to install it.

There are a few options available:

1. Use the package manager from your distro

    sudo apt-get install python3-psycopg2  # install psycopg2 module on Debian/Ubuntu
    sudo yum install python3-psycopg2      # install psycopg2 on RedHat/Fedora/CentOS

2. Specify one of psycopg, psycopg2, or psycopg2-binary in the list of dependencies when installing Patroni with pip.

## General installation for pip

Patroni can be installed with pip:

    pip install patroni[dependencies]

where `dependencies` can be either empty, or consist of one or more of the following:

etcd or etcd3

  python-etcd module in order to use Etcd as Distributed Configuration Store (DCS)

consul

  py-consul module in order to use Consul as DCS

zookeeper

  kazoo module in order to use Zookeeper as DCS

exhibitor

  kazoo module in order to use Exhibitor as DCS (same dependencies as for Zookeeper)

kubernetes

  kubernetes module in order to use Kubernetes as DCS in Patroni

raft

  pysyncobj module in order to use python Raft implementation as DCS

aws

  boto3 in order to use AWS callbacks

jsonlogger

  python-json-logger module in order to enable logging in json format

all

  all of the above (except psycopg family)

psycopg

  psycopg[binary]>=3.0.0 module

psycopg2

  psycopg2>=2.5.4 module

psycopg2-binary

  psycopg2-binary module

For example, the command in order to install Patroni together with psycopg3, dependencies for Etcd as a DCS, and AWS callbacks is:

    pip install patroni[psycopg3,etcd3,aws]

Note that external tools to call in the replica creation or custom bootstrap scripts (i.e. WAL-E) should be installed independently of Patroni.

## Package installation on Linux

Patroni packages may be available for your operating system, produced by the Postgres community for:

- RHEL, RockyLinux, AlmaLinux;

- Debian and Ubuntu;

- SUSE Enterprise Linux.

You can also find packages for direct dependencies of Patroni, like python modules that might not be available in the official operating system repositories.

For more information see the PGDG repository documentation.

If you are on a RedHat Enterprise Linux derivative operating system you may also require packages from EPEL, see EPEL repository documentation.

Once you have installed the PGDG repository for your OS you can install patroni.

Note

Patroni packages are not maintained by the Patroni developers, but rather by the Postgres community. If you require support please first try connecting on Postgres slack.

### Installing on Debian derivatives

With PGDG repo installed, see above, install Patroni via apt run:

    apt-get install patroni

### Installing on RedHat derivatives

With PGDG repo installed, see above, install patroni with an etcd DCS via dnf on RHEL 9 (and derivatives) run:

    dnf install patroni patroni-etcd

You can install etcd from PGDG if your RedHat derivative distribution does not provide packages. On the nodes that will host the DCS run:

    dnf install 'dnf-command(config-manager)'
    dnf config-manager --enable pgdg-rhel9-extras
    dnf install etcd

You can replace the version of RHEL with 8 in the repo to make pgdg-rhel8-extras if needed. The repo name is still pgdg-rhelN-extras on RockyLinux, AlmaLinux, Oracle Linux, etc…

### Installing on SUSE Enterprise Linux

You might need to enable the SUSE PackageHub repositories for some dependencies. see SUSE PackageHub documentation.

For SLES 15 with PGDG repo installed, see above, you can install patroni using:

    zypper install patroni patroni-etcd

With the SUSE PackageHub repo enabled you can also install etcd:

    SUSEConnect -p PackageHub/15.5/x86_64
    zypper install etcd

## Upgrading

Upgrading patroni is a very simple process, just update the software installation and restart the Patroni daemon on each node in the cluster.

However, restarting the Patroni daemon will result in a Postgres database restart. In some situations this may cause a failover of the primary node in your cluster, therefore it is recommended to put the cluster into maintenance mode until the Patroni daemon restart has been completed.

To put the cluster in maintenance mode, run the following command on one of the patroni nodes:

    patronictl pause --wait

Then on each node in the cluster, perform the package upgrade required for your OS:

    apt-get update && apt-get install patroni patroni-etcd

Restart the patroni daemon process on each node:

    systemctl restart patroni

Then finally resume monitoring of Postgres with patroni to take it out of maintenance mode:

    patronictl resume --wait

The cluster will now be full operational with the new version of Patroni.