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How to Install PostgreSQL on debian stretch in oder to use it with your Django application and allow remote connection


In this guide, we'll demonstrate how to install and configure PostgreSQL to use with your Django applications. We will install the necessary software, create database credentials for our application, and then start and configure a Django project to use this backend. We will start by  install the database software and the associated libraries required to interact with them. This guide assumes that you allready have a working Django project.

Step 1 – Prerequsities

apt-get install python3-pip python3-dev libpq-dev postgresql postgresql-contrib

Step 2 – Connect to PostgreSQL


After installing the PostgreSQL database server by default, it creates a user ‘postgres’ with role ‘postgres’. It also creates a system account with the same name ‘postgres’. So to connect to postgres server, login to your system as user postgres and connect database.

su - postgres
You should now be in a shell session for the postgres user. Log into a Postgres session by typing: 

psql

Step 3 – Configure PostgreSQL to allow remote connection

By default PostgreSQL is configured to be bound to “localhost”.
netstat -nlt
Proto Recv-Q Send-Q Local Address           Foreign Address         State
tcp        0      0 0.0.0.0:3306            0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:10000           0.0.0.0:*               LISTEN
tcp        0      0 192.168.1.246:53        0.0.0.0:*               LISTEN
tcp        0      0 192.168.0.245:53        0.0.0.0:*               LISTEN
tcp        0      0 127.0.0.1:53            0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:21              0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN
tcp        0      0 127.0.0.1:5432          0.0.0.0:*               LISTEN
tcp        0      0 127.0.0.1:953           0.0.0.0:*               LISTEN

As we can see above port5432 is bound to 127.0.0.1.It means any attempt to connect to the postgresql server from outside the machine will be refused. In order to fix this issue we need to change the default settings on  postgresql.conf


Step 4 – Configuring postgresql.conf

nano /etc/postgresql/9.6/main/postgresql.conf
on line 59 
# listen_addresses = 'localhost' change it to 
listen_addresses = '*'
restart postgresql server
systemctl restart postgresql

netstat -nlt
Proto Recv-Q Send-Q Local Address           Foreign Address         State
tcp        0      0 0.0.0.0:3306            0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:10000           0.0.0.0:*               LISTEN
tcp        0      0 192.168.1.246:53        0.0.0.0:*               LISTEN
tcp        0      0 192.168.0.245:53        0.0.0.0:*               LISTEN
tcp        0      0 127.0.0.1:53            0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:21              0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:5432            0.0.0.0:*               LISTEN
tcp        0      0 127.0.0.1:953           0.0.0.0:*               LISTEN

Step 5 – Configuring pg_hba.conf

try to connect to remote postgresql server using “psql”.
psql -h 192.168.0.245 -U postgres
psql: FATAL:  no pg_hba.conf entry for host "192.168.0.245", user "postgres", database "postgres", SSL on
FATAL:  no pg_hba.conf entry for host "192.168.0.245", user "postgres", database "postgres", SSL off
In order to fix it, open pg_hba.conf and add following entry on line 93.
host    all             all              0.0.0.0/0              trust
systemctl restart postgresql      # Restart postgresql server.

psql -h 192.168.0.245 -U postgres
psql (9.6.13)
SSL connection (protocol: TLSv1.3, cipher: TLS_AES_256_GCM_SHA384, bits: 256, compression: off)
Type "help" for help.

postgres=# ALTER USER postgres PASSWORD 'posttest';
ALTER ROLE    # After login, you can ALTER postgres user: (setting password)
 change pg_hba.conf file again from trust to md5
host    all             all              0.0.0.0/0              md5 
systemctl restart postgresql  # Now restart the server again
 
psql -h 192.168.0.245 -U postgres
Password for user postgres:
psql (9.6.13)
SSL connection (protocol: TLSv1.3, cipher: TLS_AES_256_GCM_SHA384, bits: 256, compression: off)
Type "help" for help.

postgres=# \l
                                  List of databases
   Name    |  Owner   | Encoding |   Collate   |    Ctype    |   Access privileges
-----------+----------+----------+-------------+-------------+-----------------------
 postgres  | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |
 template0 | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/postgres          +
           |          |          |             |             | postgres=CTc/postgres
 template1 | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/postgres          +
           |          |          |             |             | postgres=CTc/postgres
(3 rows)

postgres=# \q
<./code>

We are able to connect to postgresql server remotely.With the installation and basic configuration out of the way, we can move on to create our database and database user that we will use to connect with Django.


Step 6 – Create a Database and Database User


 CREATE DATABASE mydjango;
CREATE DATABASE
postgres=# CREATE USER mydjangouser WITH PASSWORD 'password';
CREATE ROLE
postgres=# ALTER ROLE mydjangouser SET client_encoding TO 'utf8';
ALTER ROLE
postgres=# ALTER ROLE mydjangouser SET default_transaction_isolation TO 'read committed';
ALTER ROLE
postgres=# ALTER ROLE mydjangouser SET timezone TO 'Africa/Dar_es_Salaam';
ALTER ROLE
postgres=# GRANT ALL PRIVILEGES ON DATABASE mydjango TO mydjangouser;
GRANT
postgres=# \q

Step 7 – Configure the Django Database Settings

Before we install applications within the virtual environment, we need to activate it. You can do so by typing:

source venv/bin/activate

We will install the psycopg2 package that will allow us to use the database we configured:

pip3 install psycopg2

We need to configure the Django project to use the database we created.
Open the main Django project settings file

 nano news_art/settings.py

Replace all the databases entry for sqlite3 with this code

DATABASES = {
     'default': {
         'ENGINE': 'django.db.backends.postgresql_psycopg2',
         'NAME': 'mydjango',
         'USER': 'mydjangouser',
         'PASSWORD': 'password',
         'HOST': '192.168.0.245',
         'PORT': '5432',
      }
}

Step 8 –Migrate the Database and Test your Project

Now that the Django settings are configured, we can migrate our data structures to our database and test out the server.

python3 manage.py makemigrations
No changes detected
python3 manage.py migrate
 Operations to perform:
  Apply all migrations: admin, auth, contenttypes, sessions
Running migrations:
  Applying contenttypes.0001_initial... OK
  Applying auth.0001_initial... OK
  Applying admin.0001_initial... OK
  Applying admin.0002_logentry_remove_auto_add... OK
  Applying admin.0003_logentry_add_action_flag_choices... OK
  Applying contenttypes.0002_remove_content_type_name... OK
  Applying auth.0002_alter_permission_name_max_length... OK
  Applying auth.0003_alter_user_email_max_length... OK
  Applying auth.0004_alter_user_username_opts... OK
  Applying auth.0005_alter_user_last_login_null... OK
  Applying auth.0006_require_contenttypes_0002... OK
  Applying auth.0007_alter_validators_add_error_messages... OK
  Applying auth.0008_alter_user_username_max_length... OK
  Applying auth.0009_alter_user_last_name_max_length... OK
  Applying auth.0010_alter_group_name_max_length... OK
  Applying auth.0011_update_proxy_permissions... OK
  Applying sessions.0001_initial... OK

you can test that your database is performing correctly by starting up the Django development server:

 python3 manage.py runserver 192.168.0.245:8000

In your web browser, visit your server's domain name or IP address followed by :8000 to reach default Django root page: In my case http://192.168.0.245:8000/




 

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