4.7.15 Patroni

Install Patroni and its associated support libraries using Python.
To avoid conflicts with libraries already installed on your system and for ease of uninstallation, this guide demonstrates setup using a Python virtual environment.
The following example uses "/venv/opt/patroni" as the virtual environment.
Execute this as a user with write permissions to the "/venv/opt/patroni" directory.
Additionally, if any additional support libraries are required, install them in the virtual environment in the same manner.
```
python -m venv  /venv/opt/patroni
source /venv/opt/patroni/bin/activate
cd /opt/fsepv<x>server64/OSS/patroni
pip install --no-index --find-links=./wheel ./wheel/*.whl
#If additional installation is required
pip install <additional library name>
```
Add the path to the Patroni execution environment to the environment of the user running Patroni. The execution environment is "virtual environment/bin".
```
export PATH=/venv/opt/patroni/bin:$PATH
```

Configure Patroni to run as a service. As superuser, create the service system file (/etc/systemd/system/patroni.service).
Below is an example configuration.
Specify the virtual environment where Patroni is installed (/venv/opt/patroni) for "WorkingDirectory".
<path> is the location of the Patroni configuration file required to run Patroni. The Patroni configuration file must be created beforehand.

[Unit]
Description=Patroni Master/Slave controller
After=network.target etcd.service
Wants=etcd.service

[Service]
Type=simple
User=fepuser
Group=fepuser

WorkingDirectory=/venv/opt/patroni
ExecStart=/venv/opt/patroni/bin/python3 -m patroni <path>/patroni.yml
Environment="PATRONI_REPLICATION_PASSWORD=patpass" "PATRONI_SUPERUSER_PASSWORD=patpass"
KillMode=process
TimeoutSec=30
Restart=no

[Install]
WantedBy=multi-user.target

Create the Patroni configuration file (<path>/patroni.yml).
Please create it by referring to the OSS manual.
Important points to note during creation are documented as comments here for your reference.

# Patroni configuration
scope: patroni_cluster # Cluster name. Set to the same value on all servers.
name: node1

[Text omitted]

# PostgreSQL configuration
postgresql:
  data_dir: /home/fepuser/pg_pt
  bin_dir:  /opt/ fsepv<x>server64/bin
  connect_address: xx.yyy.zzzz.www:27500 # This server's IP address and PostgreSQL port
  listen: xxx.yyy.zzz.www:27500          # This server's IP address and PostgreSQL port
  # User and password for Patroni to connect to PostgreSQL
  # Specify the patroni_user and its password created in the service system file
  authentication:
    replication:
      username: patroni_user
      password: ${PATRONI_REPLICATION_PASSWORD}
    superuser:
      username: patroni_user
      password: ${PATRONI_SUPERUSER_PASSWORD}

    [Text omitted]

  pg_hba:
    # Replication users and superusers must be specified.
    - host replication patroni_user xx.yyy.zzz.0/24 md5 # Replication user
    - host all patroni_user xx.yyy.zzz.0/24 md5         # superuser (patroni_user)
    - host all all xx.yyy.zzz.0/24 md5                  # Other users (as needed)
    - host replication patroni_user XX.YY.ZZZ.0/24 md5
    - host all patroni_user XX.YY.ZZZ.0/24 md5
    - host all all XX.YY.ZZZ.0/24 md5
    - host all all xx.zz.yy.0/24 md5

# initdb configuration
initdb:
  - encoding: UTF8
  - locale: ja_JP.UTF-8
  - data-checksums # Required when using pg_rewind, etc.

# Recovery operation settings
recovery_conf:
  [Text omitted]


# Etcd configuration
etcd3:
  [Text omitted]


# REST API Configuration (for Patroni health checks and management)
restapi:
  [Text omitted]


# Must be specified when running initdb with Patroni.
bootstrap:
  dcs:
    postgresql:
      use_pg_rewind: true

4.7.15 Patroni

4.7.15.1 Removing Patroni