====== Flask app on Debian ======

This guide lists the steps in order to setup the environment for the hosting of a Flask-based app. I'm assuming the IT professional is starting from scratch and a fresh, clean install of Debian is in place.

1) Install sudo

Debian does not come with the sudo program so it has to be installed with ''apt install sudo''.

2) Allow remote ssh:

In order to allow root account login via ssh, edit the **sshd_config** file. As root, type:

''nano /etc/ssh/sshd_config''

Add the following line to the file (at the end of the file, for example):

''PermitRootLogin yes''

…and restart the service:

''service ssh restart''

Add newuser (or whatever plain user) to sudoers:

as root, run: ''usermod -aG sudo newuser''

The -aG option tells the system to append the user to the specified group. (The -a option is only used with G.)


===== Install PostgreSQL =====

PostgreSQL can be installed with:

''apt install postgresql postgresql-contrib''

PostgreSQL version: PostgreSQL 13.5

Change to user postgres:

<code>su - postgres

psql

postgres=# create user melvin with encrypted password 'password'; 

create database flask_db;

grant all privileges on database flaskdb to melvin;

createdb postgres

GRANT ALL PRIVILEGES ON DATABASE postgres TO postgres;

</code>

===== Allow remote access to PostgreSQL =====

Exit and run as root:

''nano /etc/postgresql/13/main/postgresql.conf''

add:

''listen_addresses = '*'     # what IP address(es) to listen on;''

Next, you also have to edit the ''pg_hba.conf'' file to control access at a finer grained level. The file path is, in my case: ''/etc/postgresql/13/main/pg_hba.conf''

===== PostGIS =====

<code>sudo apt install postgis postgresql-13-postgis-3

sudo -i -u postgres
</code>


===== Troubleshooting =====


https://www.postgresql.r2schools.com/how-to-check-postgresql-is-running-or-not/

===== Sources =====

https://help.clouding.io/hc/en-us/articles/360021332399-How-to-Deploy-a-Python-App-on-Debian-10

"Externalize" PostgreSQL:\\
https://www.postgresql.org/docs/current/auth-pg-hba-conf.html\\
https://stackoverflow.com/questions/3278379/how-to-configure-postgresql-to-accept-all-incoming-connections\\
https://stackoverflow.com/questions/59101635/even-with-listen-addresses-in-postgres-remote-login-is-not-working