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Installating pgmoneta

This tutorial will show you how to do a simple installation of pgmoneta.

At the end of this tutorial you will have a backup of a PostgreSQL cluster, and will be streaming Write-Ahead Log (WAL) to pgmoneta.

Preface

This tutorial assumes that you have an installation of PostgreSQL 10+ and pgmoneta.

For RPM based distributions such as Fedora and RHEL you can add the PostgreSQL YUM repository and do the install via

dnf install -y postgresql10 postgresql10-server pgmoneta
    

Initialize cluster

export PATH=/usr/pgsql-10/bin:$PATH
initdb /tmp/pgsql
    

as postgres user

Remove default access

Remove

host    all             all             127.0.0.1/32            trust
host    all             all             ::1/128                 trust
host    replication     all             127.0.0.1/32            trust
host    replication     all             ::1/128                 trust
    

from /tmp/pgsql/pg_hba.conf.

as postgres user

Add access for users and a database

Add

host    mydb             myuser          127.0.0.1/32            md5
host    mydb             myuser          ::1/128                 md5
host    postgres         repl            127.0.0.1/32            md5
host    postgres         repl            ::1/128                 md5
host    replication      repl            127.0.0.1/32            md5
host    replication      repl            ::1/128                 md5
    

to /tmp/pgsql/pg_hba.conf. Or use scram-sha-256.

Remember to check the value of password_encryption in /tmp/pgsql/postgresql.conf to setup the correct authentication type.

as postgres user

Make sure that replication level is set

Check that

wal_level = replica
    

is set in /tmp/pgsql/postgresql.conf - or logical

as postgres user

Start PostgreSQL

pg_ctl  -D /tmp/pgsql/ start
    

as postgres user

Add users and a database

createuser -P myuser
createdb -E UTF8 -O myuser mydb
    

with mypass as the password.

Then

psql postgres
CREATE ROLE repl WITH LOGIN REPLICATION PASSWORD 'secretpassword';
\q
    

as postgres user

Verify access

For the user (standard) (using mypass)

psql -h localhost -p 5432 -U myuser mydb
\q
    

For the user (pgmoneta) (using secretpassword)

psql -h localhost -p 5432 -U repl postgres
\q
    

as postgres user

Add pgmoneta user

sudo su -
useradd -ms /bin/bash pgmoneta
passwd pgmoneta
exit
    

as postgres user

Create pgmoneta configuration

Switch to the pgmoneta user

sudo su -
su - pgmoneta
    

Add the master key and create vault

pgmoneta-admin master-key
pgmoneta-admin -f pgmoneta_users.conf -U repl -P secretpassword add-user
    

You have to choose a password for the master key - remember it !

Create the pgmoneta.conf configuration

cat > pgmoneta.conf
[pgmoneta]
host = *
metrics = 5001

base_dir = /home/pgmoneta/backup

compression = zstd

storage_engine = local

retention = 7

log_type = file
log_level = info
log_path = /tmp/pgmoneta.log

unix_socket_dir = /tmp/
pgsql_dir = /usr/pgsql-10/bin/

[primary]
host = localhost
port = 5432
user = repl
      

and press Ctrl-D

as postgres user

Create base directory

mkdir backup
      

as pgmoneta user

Start pgmoneta

pgmoneta -c pgmoneta.conf -u pgmoneta_users.conf
      

as pgmoneta user

Create a backup

In another terminal

pgmoneta-cli -c pgmoneta.conf backup primary
      

as pgmoneta user

View backup

In another terminal

pgmoneta-cli -c pgmoneta.conf details
      

as pgmoneta user

Shell completion

There is a minimal shell completion support for pgmoneta-cli and pgmoneta-admin. If you are running such commands from a Bash or Zsh, you can take some advantage of command completion.

Installing command completions in Bash

There is a completion script into contrib/shell_comp/pgmoneta_comp.bash that can be used to help you complete the command line while you are typing.

It is required to source the script into your current shell, for instance by doing:

source contrib/shell_comp/pgmoneta_comp.bash
        

At this point, the completions should be active, so you can type the name of one the commands between pgmoneta-cli and pgmoneta-admin and hit TAB to help the command line completion.

Installing the command completions on Zsh

In order to enable completion into zsh you first need to have compinit loaded; ensure your .zshrc file contains the following lines:

autoload -U compinit
compinit
        

and add the sourcing of the contrib/shell_comp/pgmoneta_comp.zsh file into your ~/.zshrc also associating the _pgmoneta_cli and _pgmoneta_admin functions to completion by means of compdef:

source contrib/shell_comp/pgmoneta_comp.zsh
compdef _pgmoneta_cli    pgmoneta-cli
compdef _pgmoneta_admin  pgmoneta-admin
        

If you want completions only for one command, e.g., pgmoneta-admin, remove the compdef line that references the command you don't want to have automatic completion. At this point, digit the name of a pgmoneta-cli or pgmoneta-admin command and hit TAB to trigger the completion system.