How to Install and Configure Postgres 14 on Alma Linux 9

In this guide we are going to install Postgresql 14 in Alma Linux 9. This will also work in RHEL 9 and its derivatives.

Postgresql is an open source object-relational database system with over 30 years of active development that has earned it a strong reputation for reliability, feature robustness, and performance. Postgres, is a free and open-source relational database management system emphasizing extensibility and SQL compliance. It was originally named POSTGRES, referring to its origins as a successor to the Ingres database developed at the University of California, Berkeley. PostgreSQL is used as the primary data store or data warehouse for many web, mobile, geospatial, and analytics applications. PostgreSQL can store structured and unstructured data in a single product.

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# Prerequisites

To follow along, ensure you have the following:

Alma linux 9 or RHEL 9 based server
Root access to the server or user with root access
Internet access from the server
Basic knowledge of Linux terminal

# Table of contents

Ensure the server is up to date
Installing and starting Postgres Server
PostgreSQL Roles and Databases Authentication Methods
Connecting to postgres database
Configuring postgres 14 instance for remote access
User management

# 1. Ensure the server is up to date

Before proceeding, let us ensure that our server has up to date packages. Use this command to update the packages:

$ sudo dnf -y update

# 2. Installing and starting Postgres Server

The default Alma Linux 9 repositories has an older version of postgres.

We will use the repo provided by the postgres team to set up repositories for postgres 14 then install the package.

Let us Install the repository RPM using this command:

sudo dnf install -y https://download.postgresql.org/pub/repos/yum/reporpms/EL-9-x86_64/pgdg-redhat-repo-latest.noarch.rpm

Then to avoid conflicts, let us disable the built-in PostgreSQL module:

sudo dnf -qy module disable postgresql

Finally install PostgreSQL 14 server:

sudo dnf install -y postgresql14-server

Let’s also install the Contrib package which provides several additional features for the PostgreSQL database system:

sudo dnf install -y postgresql14-contrib

Once the installation is complete, initialize the PostgreSQL database with the following command:

$ sudo /usr/pgsql-14/bin/postgresql-14-setup initdb
Initializing database ... OK

Start the postgres service with this command:

sudo systemctl start postgresql-14

Then enable the service so it starts when the server reboots.

$ sudo systemctl enable postgresql-14

Confirm that Postgres is running:

$ sudo systemctl status postgresql-14
● postgresql-14.service - PostgreSQL 14 database server
     Loaded: loaded (/usr/lib/systemd/system/postgresql-14.service; enabled; vendor preset: disabled)
     Active: active (running) since Tue 2022-07-05 19:00:58 UTC; 1min 2s ago
       Docs: https://www.postgresql.org/docs/14/static/
   Main PID: 112444 (postmaster)
      Tasks: 8 (limit: 49928)
     Memory: 16.6M
        CPU: 62ms
     CGroup: /system.slice/postgresql-14.service
             ├─112444 /usr/pgsql-14/bin/postmaster -D /var/lib/pgsql/14/data/
             ├─112445 "postgres: logger "
             ├─112447 "postgres: checkpointer "
             ├─112448 "postgres: background writer "
             ├─112449 "postgres: walwriter "
             ├─112450 "postgres: autovacuum launcher "
             ├─112451 "postgres: stats collector "
             └─112452 "postgres: logical replication launcher "

Jul 05 19:00:58 kip-alma9srv.citizix.com systemd[1]: Starting PostgreSQL 14 database server...
Jul 05 19:00:58 kip-alma9srv.citizix.com postmaster[112444]: 2022-07-05 19:00:58.863 UTC [112444] LOG:  redirecting log output to logging collector process
Jul 05 19:00:58 kip-alma9srv.citizix.com postmaster[112444]: 2022-07-05 19:00:58.863 UTC [112444] HINT:  Future log output will appear in directory "log".
Jul 05 19:00:58 kip-alma9srv.citizix.com systemd[1]: Started PostgreSQL 14 database server.

The Active: active (running) shows that the service is up and running.

Next, let us verify that the installation was successful by connecting to the PostgreSQL database server and printing its version:

sudo -u postgres psql -c "SELECT version();"

Output:

$ sudo -u postgres psql -c "SELECT version();"
                                                 version
----------------------------------------------------------------------------------------------------------
 PostgreSQL 14.4 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 11.2.1 20220127 (Red Hat 11.2.1-9), 64-bit
(1 row)

# 3. PostgreSQL Roles and Databases Authentication Methods

PostgreSQL uses a concept called roles to handle client authentication and authorization. By default, Postgres is set up to use ident authentication, meaning that it associates Postgres roles with a matching Unix/Linux system account. If a role exists within Postgres, a Unix/Linux username with the same name is able to sign in as that role.

The installation procedure created a user account called postgres that is associated with the default postgres role. In order to use PostgreSQL, you can log in to that account.

PostgreSQL supports multiple authentication methods . The most commonly-used methods are:

Trust – A role can connect without a password, as long as the conditions defined in the pg_hba.conf are met.
Password – A role can connect by providing a password. The passwords can be stored as scram-sha-256, md5, and password (clear-text).
Ident – Only supported on TCP/IP connections. It works by obtaining the client’s operating system user name, with an optional user name mapping.
Peer – Same as Ident, but it is supported on local connections only.

# 4. Connecting to postgres database

By Switching to postres user

Switch over to the postgres account on your server by typing this in the terminal;:

sudo -i -u postgres

You can now access a Postgres prompt immediately by typing:

$ psql
psql (14.4)
Type "help" for help.

postgres=#

This will log you into the PostgreSQL prompt, and from here you are free to interact with the database management system right away.

By running the command as postgres user

Use this to run the command directly as the postgres user using sudo

sudo -u postgres psql

Output:

$ sudo -u postgres psql
psql (14.0)
Type "help" for help.

postgres=#

Ensure that you run the above command as a user that has sudo privileges.

# 5. Configuring postgres 14 instance for remote access

To achieve this, we will modify postgres configuration files. We need to open the files and adjust the configs are required. The main configuration file for Postgresql 14 can be found in this path /var/lib/pgsql/14/data/pg_hba.conf

Let’s change peer identification to trust:

sed -i '/^local/s/peer/trust/' /var/lib/pgsql/14/data/pg_hba.conf

Change ident identification to md5 to allow password login.

sed -i '/^host/s/ident/md5/' /var/lib/pgsql/14/data/pg_hba.conf

Add a block to allow access from everywhere:

Add this content to the file /var/lib/pgsql/14/data/pg_hba.conf

host    all             all             0.0.0.0/0                md5

Ensure PostgreSQL is listening on *

Add this line to the config here /var/lib/pgsql/14/data/postgresql.conf

listen_addresses='*'

Enable and restart postgresql server to reload the configurations:

sudo systemctl restart postgresql-14

# 6. User management

# Creating Superuser

Now that everything is set up, let us create a super user.
Connect to the DB as postres role:

$ sudo -u postgres psql
psql (14.0)
Type "help" for help.

postgres=#

Create super user with name root:

CREATE ROLE root WITH LOGIN SUPERUSER CREATEDB CREATEROLE PASSWORD 'passwordhere';

Output:

postgres=# CREATE ROLE root WITH LOGIN SUPERUSER CREATEDB CREATEROLE PASSWORD 'passwordhere';
CREATE ROLE
postgres=# \du
                                   List of roles
 Role name |                         Attributes                         | Member of
-----------+------------------------------------------------------------+-----------
 postgres  | Superuser, Create role, Create DB, Replication, Bypass RLS | {}
 root      | Superuser, Create role, Create DB                          | {}

postgres=#

# Managing Application Users

Use this to create a database, create a user and grant that user all accesss to that database:

create database app_db_name;
create user app_user with encrypted password 'dbpassword';
grant all privileges on database app_db_name to app_user;

Checkout this comprehensive guide on user and permission management in postgres here.

# Connecting to the instance from remote host

Use this command to connect to the postgres instance from local machine:

psql 'postgres://<username>:<password>@<host>:<port>/<db>?sslmode=disable'

# like
psql 'postgres://root:passwordhere@192.160.1.20:5432/postgres?sslmode=disable'

# Conclusion

Up to this point we have managed to install Postgresql 14 on an Alma Linux 9 server, do some basic configurations then do basic user management.